JP3985488B2 - Semiconductor light emitting device and method for manufacturing semiconductor light emitting device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a semiconductor light emitting device and a method for manufacturing the semiconductor light emitting device, and more particularly, in a semiconductor light emitting device using a nitride compound semiconductor and a method for manufacturing the semiconductor light emitting device, having a tilted crystal plane inclined with respect to the main surface of the substrate. The present invention relates to a semiconductor light emitting device in which a first conductive type layer, an active layer, and a second conductive type layer are formed in a crystal layer so as to extend in a plane parallel to an inclined crystal plane, and a method for manufacturing the semiconductor light emitting device.
[0002]
[Prior art]
Conventionally, a semiconductor light emitting device using a nitride-based compound semiconductor has a low-temperature buffer layer formed on a sapphire substrate, an n-side contact layer made of, for example, silicon-doped GaN is formed thereon, and silicon-doped GaN is used. An n-side cladding layer made of silicon, an active layer made of silicon-doped InGaN, a p-side cladding layer made of magnesium-doped AlGaN, a p-side contact layer made of magnesium-doped GaN, and the like are laminated.
[0003]
Semiconductor light-emitting elements having such a structure are commercialized and mass-produced as blue and green light-emitting diodes including 450 nm to 530 nm, and are used in various application devices such as large displays. And in order to raise the light emission output of each semiconductor light-emitting element and to improve the brightness | luminance of an application apparatus, the impurity concentration doped to the cladding layer of a semiconductor light-emitting element is raised and the brightness | luminance of an application apparatus is improved.
[0004]
When a nitride-based semiconductor is grown on a sapphire substrate, a sapphire substrate having a C-plane as a main surface is usually used. Since the nitride-based semiconductor layer is formed to extend in a plane parallel to the substrate main surface, the surface of the nitride-based semiconductor layer such as an active layer formed on the substrate main surface and a clad layer sandwiching the active layer is also present. It has a C surface.
[0005]
When it is selectively grown on the C-plane of the sapphire substrate, a crystal layer with a sharp tip surrounded by the (1-101) plane, that is, the S-plane is formed (for example, the specification of Japanese Patent No. 2830814) However, there is no example that is actively used as an electronic device or a light-emitting device, as a base layer of a crystal structure from further selective growth. It is only used.
[0006]
[Problems to be solved by the invention]
However, if the amount of impurities doped in the cladding layer is increased too much in order to improve the light emission output of the semiconductor light emitting device, the impurities are likely to diffuse into the active layer, thereby reducing the crystal quality of the active layer and degrading the active layer. Invite.
[0007]
Furthermore, in the case of a semiconductor light emitting device in which a crystal layer is formed by extending in a plane parallel to the tilted crystal plane using selective growth, the cladding layer is formed in a crystal layer having a tilted crystal plane. Impurities are more easily diffused into the active layer than the semiconductor light emitting device.
[0008]
Therefore, the present invention relates to a semiconductor light emitting device formed by extending a crystal layer having an inclined crystal plane in a plane parallel to the inclined crystal plane using selective growth, and a method for manufacturing the semiconductor light emitting device. It is an object of the present invention to provide a semiconductor light emitting device capable of preventing impurities from diffusing from the layer to the active layer and preventing the deterioration of the active layer, and a method for manufacturing the semiconductor light emitting device.
[0009]
[Means for Solving the Problems]
The semiconductor light emitting device in the present invention is A substrate, On the board Been formed Crystal layer having an inclined crystal plane inclined with respect to the main surface of the substrate And formed in the crystal layer First conductivity type layer, active layer, and second conductivity type layer extending in a plane parallel to the tilted crystal plane And at least one of the first electrode formed on the second conductivity type layer, the active layer and the first conductivity type layer, and the active layer and the second conductivity type layer. Undoped crystal layer extending in a plane parallel to the tilted crystal plane And a second electrode formed in a plane parallel to the main surface of the substrate It is characterized by that.
[0010]
By forming an undoped crystal layer in the vicinity of the active layer formed in a plane parallel to the tilted crystal plane in the crystal layer having the tilted crystal plane tilted with respect to the main surface of the substrate, The undoped crystal layer can prevent impurities from diffusing from the conductive layer to the active layer due to the inclination. In particular, it is possible to prevent impurities from diffusing from the second conductivity type layer, which is the outermost layer of the crystal layer, to the active layer. Furthermore, since the impurity that diffuses from the conductive type layer to the active layer can be prevented by the undoped crystal layer, it is possible to form a semiconductor light emitting device in which the active layer is not deteriorated by the impurity without lowering the crystal quality of the active layer. .
[0011]
In a semiconductor light emitting device in which an active layer is formed in a crystal layer having an inclined crystal plane inclined with respect to the substrate main surface and extending in a plane parallel to the inclined crystal plane, impurities from the conductive type layer to the active layer are formed. Since diffusion can be prevented, the impurity concentration of the conductive layer can be increased, and a semiconductor light-emitting element with high emission efficiency can be formed.
[0012]
In the method of manufacturing a semiconductor light emitting device according to the present invention, a mask layer or a crystal seed layer having an opening is formed on a substrate. Shi And selectively forming a crystal layer having an inclined crystal plane inclined from the opening or the crystal seed layer with respect to the main surface of the substrate Shi Forming a first conductivity type layer, an active layer, and a second conductivity type layer extending in a plane parallel to the inclined crystal plane in the crystal layer Shi , A first electrode is formed on the second conductivity type layer, and is a plane parallel to the inclined crystal plane between at least one of the active layer and the first conductivity type layer and between the active layer and the second conductivity type layer. An undoped crystal layer extending inward is formed, and a second electrode is formed in a plane parallel to the main surface of the substrate It is characterized by that.
[0013]
By forming an undoped crystal layer adjacent to an active layer formed in a plane parallel to the tilted crystal plane in a crystal layer having a tilted crystal plane tilted with respect to the main surface of the substrate, The undoped crystal layer can prevent impurities from diffusing from the conductive layer to the active layer due to the inclination. In particular, it is possible to prevent impurities from diffusing from the second conductivity type layer, which is the outermost layer of the crystal layer, to the active layer. Furthermore, since the undoped crystal layer can prevent impurities diffusing from the conductive type layer to the active layer, the active layer can be prevented from being deteriorated by the impurity without lowering the crystal quality of the active layer.
[0014]
In a semiconductor light emitting device in which an active layer is formed in a crystal layer having an inclined crystal plane inclined with respect to the substrate main surface and extending in a plane parallel to the inclined crystal plane, impurities from the conductive type layer to the active layer are formed. Since diffusion can be prevented, the impurity concentration of the conductive layer of the semiconductor light emitting element can be increased, and the light emission efficiency can be increased.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
The semiconductor light-emitting device according to the present invention includes a first conductivity type layer extending in a plane parallel to the tilted crystal plane, wherein a crystal layer having a tilted crystal plane tilted with respect to the main surface of the substrate is formed on the substrate. A layer and a second conductivity type layer are formed in the crystal layer, and an undoped crystal layer extending in a plane parallel to the inclined crystal plane is formed in the crystal layer in the vicinity of the active layer.
[0016]
The substrate used in the present invention is not particularly limited as long as it can form a wurtzite type compound semiconductor layer, and various substrates can be used. For example, sapphire (Al ₂ O ₃ , A plane, R plane, C plane. ), SiC (including 6H, 4H, 3C), GaN, Si, ZnS, ZnO, AlN, LiMgO, LiGaO ₂ , GaAs, MgAl ₂ O ₄ , InAlGaN or the like, preferably a hexagonal substrate or cubic substrate made of these materials, and more preferably a hexagonal substrate. For example, in the case of using a sapphire substrate, a sapphire substrate having a C-plane as a main surface, which is often used when growing a gallium nitride (GaN) -based compound semiconductor material, can be used. In this case, the C-plane as the substrate main surface is a plane substantially equivalent to the S-plane including the plane orientation inclined in the range of 5 to 6 degrees. It is also possible to use a silicon substrate that is widely used in the manufacture of semiconductor devices.
[0017]
The crystal layer formed on the substrate has an inclined crystal plane inclined with respect to the main surface of the substrate, and extends in a plane parallel to the inclined crystal surface inclined with respect to the main surface of the substrate described later. There is no particular limitation as long as it is a material layer that can form the one conductivity type layer, the active layer, and the second conductivity type layer. As such a material layer, a wurtzite type compound semiconductor layer is preferably selected because a facet structure is formed in a process described later. The compound semiconductor layer is preferably a nitride compound semiconductor having a wurtzite crystal structure, a BeMgZnCdS compound semiconductor, a BeMgZnCdO compound semiconductor, or the like. As the crystal layer made of a nitride compound semiconductor, for example, a group III compound semiconductor can be used, and further, a gallium nitride (GaN) compound semiconductor, an aluminum nitride (AlN) compound semiconductor, and an indium nitride (InN) system. A compound semiconductor, an indium gallium nitride (InGaN) compound semiconductor, and an aluminum gallium nitride (AlGaN) compound semiconductor are preferable, and a gallium nitride compound semiconductor is particularly preferable. As an example, an undoped GaN layer may be formed on a sapphire substrate, and then a Si-doped GaN layer may be formed. In the present invention, InGaN, AlGaN, GaN, etc. do not necessarily refer to nitride-based compound semiconductors of only ternary mixed crystals but only binary mixed crystals. For example, InGaN does not change the action of InGaN. Needless to say, a small amount of Al and other impurities are included in the scope of the present invention. In the present specification, a nitride refers to a compound in which B, Al, Ga, In, and Ta are group III, and group V contains N, and is within 1% of the total or 1 × 10 ²⁰ cm ³ The following impurities may be included.
[0018]
Examples of the crystal layer growth method include various vapor phase growth methods, for example, vapor phase growth methods such as organometallic compound vapor phase growth method (MOCVD (MOVPE) method) and molecular beam epitaxy method (MBE method). And hydride vapor phase epitaxy (HVPE). Among them, the MOCVD method can quickly obtain a crystal with good crystallinity. In the MOCVD method, TMG (trimethylgallium) and TEG (triethylgallium) are used as the Ga source, TMA (trimethylaluminum) and TEA (triethylaluminum) are used as the Al source, TMI (trimethylindium) and TEI (triethylindium) are used as the In source. ) And the like, and gases such as ammonia and hydrazine are used as the nitrogen source. As the impurity source, silane gas is used for Si, germane gas is used for Ge, Cp2Mg (cyclopentadienylmagnesium) is used for Mg, and DEZ (diethyl zinc) is used for Zn. In general, in the MOVPE method, an InAlGaN-based compound semiconductor can be epitaxially grown by supplying these gases to the surface of a heated substrate for decomposition.
[0019]
It is preferable to form a base growth layer on the substrate before forming the crystal layer, and the base growth layer is made of a gallium nitride layer, an aluminum nitride layer, or the like. The underlying growth layer may be formed by combining a low-temperature buffer layer and a high-temperature buffer layer, or a combination of a buffer layer and a crystal seed layer that functions as a crystal seed. Similar to the crystal layer, the underlying growth layer can also be formed by various vapor deposition methods, such as organometallic compound vapor deposition method (MOVPE method), molecular beam epitaxy method (MBE method), halide vapor phase growth method. A vapor phase growth method such as a method (HVPE method) can be used.
[0020]
If crystal growth starts from a low-temperature buffer layer, polycrystals are likely to be deposited on the mask. Therefore, by growing a different surface from the substrate on the crystal seed layer, a crystal with better crystallinity will grow. it can. In addition, in order to perform crystal growth using selective growth, if there is no crystal seed layer, it is formed from the buffer layer. However, if selective growth is performed from the buffer layer, it grows in a portion where growth is not obstructed. Is likely to occur. Therefore, by using the crystal seed layer, it is possible to grow a crystal with high selectivity in a region where growth is necessary.
[0021]
By forming the buffer layer, the lattice mismatch between the substrate and the nitride compound semiconductor can be alleviated. However, when using a substrate having a lattice constant close to that of the nitride compound semiconductor or a substrate having the same lattice constant, the buffer is used. A nitride-based compound semiconductor may be grown without forming a layer. For example, a buffer layer having a low temperature of AlN may be formed on SiC, and AlN and GaN may be grown on the Si substrate as a buffer layer without reducing the temperature. Even when a buffer layer having a low temperature is formed as described above, good quality GaN can be formed. In addition, as in the case of using a GaN substrate, the buffer layer may not be particularly provided.
[0022]
In the present invention, a selective growth method can be used to form an inclined crystal plane inclined with respect to the main surface of the substrate. The tilted crystal plane tilted with respect to the main surface of the substrate depends on the selection of the main surface of the substrate, but when the wurtzite (0001) plane (C plane) is the main substrate plane, (1-100 ) Plane (M plane), (1-101) plane (S plane), (11-20) plane (A plane), (1-102) plane (R plane), (1-123) plane (N plane) , (11-22) planes, and tilted crystal planes selected from the equivalent crystal planes. In particular, it is preferable to use the S plane, the (11-22) plane, and crystal planes equivalent to these including the plane orientation inclined in the range of 5 to 6 degrees. When the selective crystal growth layer is formed by selective growth, the S plane or a plane substantially equivalent to the S plane can be easily formed. The S plane is a stable plane that can be seen when selectively grown on the C + plane (the plane index of the C + plane is (0001)), and is a relatively easy plane that is (1) in the hexagonal plane index. -101). In addition, the S + plane and the S− plane exist for the S plane in the same manner as the C + plane and the C− plane exist on the C plane. The S + plane, which is a stable plane, is grown on the S plane, and this is the S plane.
[0023]
As for the S plane, when the crystal layer is composed of the gallium nitride compound semiconductor as described above, the number of bonds from Ga to N is 2 or 3 on the S plane next to the C-plane. Here, since the C-plane cannot be practically obtained on the C + plane, the number of bonds on the S-plane is the largest. For example, when nitride is grown on a sapphire substrate having a C + plane as a main surface, the surface of a wurtzite nitride is generally a C + plane, but the S plane is stably formed by utilizing selective growth. The N bond, which tends to desorb in the plane parallel to the C + plane, is bonded with one bond from Ga, whereas the inclined S plane is bonded with at least one bond. It will be. Therefore, the V / III ratio is effectively increased, which is advantageous for improving the crystallinity of the laminated structure. Further, when growing in a different direction from the substrate, dislocations extending upward from the substrate may be bent, which is advantageous for reducing defects.
[0024]
In the semiconductor light emitting device of the present invention, the crystal layer has a structure having an inclined crystal plane inclined with respect to the main surface of the substrate, and in particular, the crystal layer has an S plane or a plane substantially equivalent to the S plane. It may have a structure that each forms a hexagonal pyramid-shaped slope, or a surface substantially equivalent to the S-plane or S-plane constitutes a substantially hexagonal pyramid-shaped slope, and is substantially on the C-plane or C-plane. In other words, a structure in which the substantially equivalent surface constitutes the upper plane portion of the substantially hexagonal frustum shape, that is, a substantially hexagonal frustum shape may be employed. These substantially hexagonal pyramid shapes and substantially hexagonal frustum shapes do not need to be exactly hexagonal pyramids, and include those in which some surfaces are lost. In a preferred example, the inclined crystal faces are arranged so as to be almost symmetrical with respect to six faces. The term “substantially symmetrical” includes not only the case where the shape is completely symmetric but also the case where the shape is slightly different from the symmetric shape. Further, the ridge line between the crystal planes of the crystal layer is not necessarily a straight line, and the substantially hexagonal pyramid shape and the substantially hexagonal frustum shape may be linearly extended shapes.
[0025]
As a specific selective growth method, the selective growth may be performed selectively using an opened portion of a mask layer formed on the base growth layer or before the formation of the base growth layer, or one of the base growth layers. Or by selectively removing parts. When a window region is formed by selectively opening a mask layer formed on the underlying growth layer and selectively growing, the mask layer can be formed of, for example, a silicon oxide layer or a silicon nitride layer, and the thickness is illustrative. In the range of 100 to 500 nm. In the mask layer on the base crystal layer, an opening for growing the selective crystal growth layer is formed by using a photolithography technique and a required etchant. The size of the opening is set according to the characteristics of the semiconductor light emitting device to be created. As an example, the size is about 10 μm, and the shape is rectangular, square, circular, hexagonal, or the like. Various shapes such as a shape, a triangular shape, a rhombus shape, and an elliptical shape can be used. When the substantially hexagonal frustum shape or the substantially hexagonal pyramid shape is linearly extended as described above, the pyramid frustum or pyramid shape in which one direction is the longitudinal direction makes the window region of the mask layer a band shape. Or by making the crystal seed layer into a strip shape. When the underlying growth layer is composed of a buffer layer and a crystal seed layer, for example, the crystal seed layer on the buffer layer is subdivided into small regions with a diameter of about 10 μm, and the S-plane or the like is formed by crystal growth from each portion. It is possible to form a crystal layer having the same. For example, the subdivided crystal seed layers can be arranged so as to be separated to allow for a margin for separation as a semiconductor light emitting device, and each small region can be a circular shape, a square shape, a hexagonal shape, a triangular shape, or the like. A shape such as a shape, a rectangular shape, a rhombus, and a deformed shape thereof can be used. The crystal growth from the crystal seed part is made by producing a selective mask, leaving a part with the mask, etching the other part to obtain the seed crystal part, and selectively growing from the seed crystal part. Less affected by mask contamination.
[0026]
By using selective growth, the window area of the mask layer is made to be a circle of about 10 μm (or a hexagon with a side of 1-100 direction, or a hexagon with a side of 11-20), and so on. Easy to manufacture up to the area. Further, if the S plane is in a direction different from the substrate, there is an effect of bending the dislocation and an effect of shielding the dislocation, which is useful for reducing the dislocation density. In addition, when the substantially hexagonal frustum shape or the substantially hexagonal pyramid shape is a shape that extends in a straight line, the pyramid frustum or pyramid shape that has one direction as the longitudinal direction makes the window region of the max layer a belt shape, This is possible by making the crystal seed layer into a strip shape.
[0027]
In the experiments conducted by the present inventors, when the hexagonal frustum shape grown using cathodoluminescence was observed, the crystal of the S plane was of good quality and the luminous efficiency was higher than that of the C + plane. It is shown. In particular, since the growth temperature of the InGaN active layer is 700 to 800 ° C., the decomposition efficiency of ammonia is low, and more N species are required. When the surface was observed with AFM, the steps were aligned and a surface suitable for InGaN uptake was observed. Furthermore, the growth surface of the Mg-doped layer generally has a poor surface state at the AFM level, but it has been found that this Mg-doped layer also grows in a good surface state due to the growth of the S-plane, and the doping conditions differ considerably. . When microphotoluminescence mapping is performed, measurement can be performed with a resolution of about 0.5 to 1 μm. However, in a normal method grown on the C + plane, unevenness of about 1 μm pitch exists, and S grows with selective growth. Uniform results were obtained for the sample from which the surface was obtained. Further, the flatness of the slope as seen by SEM is also smoother than the C + plane.
[0028]
Further, in the case of selective growth using a selective growth mask, since there is no lateral growth when growing only on the selective mask opening, lateral growth is performed using microchannel epitaxy from the window region. An enlarged shape is possible. It has been found that lateral growth using such microchannel epitaxy makes it easier to avoid threading dislocations and reduces dislocations. In addition, the light emitting region is increased by such lateral growth, and it is possible to achieve uniform current, avoid current concentration, and reduce current density.
[0029]
The semiconductor light emitting device of the present invention includes a first conductive type layer, an active layer, and a second conductive type layer that extend in a plane parallel to an inclined crystal plane inclined with respect to a main surface of a substrate. An undoped crystal layer is formed in the vicinity of the active layer. At this time, the undoped crystal layer is formed close to the active layer. However, the undoped crystal layer may be formed so as to sandwich the active layer, or only on the first conductivity type layer side or the second conductivity type layer side. You may do it. In the case of forming only one of them, since the diffusion of impurities from the second conductivity type layer side to the active layer is particularly severe, it is preferably formed on the second conductivity type layer side. When the film thickness of the undoped crystal layer formed in the vicinity of the active layer is smaller than 10 mm, the carrier injection efficiency is increased, but the crystallinity of the crystal layer formed on the undoped crystal layer is decreased and the light emission efficiency is increased. If the thickness is lower than 100 nm, the crystallinity of the crystal layer formed on the undoped crystal layer is increased, but the carrier injection efficiency is decreased and the light emission efficiency is decreased. The first conductivity type is a p-type or n-type cladding layer, and the second conductivity type is the opposite conductivity type. For example, when the crystal layer constituting the S plane is constituted by a silicon-doped gallium nitride compound semiconductor layer, the n-type cladding layer is constituted by a silicon-doped gallium nitride compound semiconductor layer, and an InGaN layer is an active layer thereon And a p-type cladding layer formed thereon using a magnesium-doped gallium nitride compound semiconductor layer. Then, an undoped GaN layer that is an undoped crystal layer is formed in the vicinity of the InGaN layer that is an active layer. It is also possible to form a multiple structure by forming guide layers such as GaN and InGaN layers on both sides of the active layer, and between the active layer and the guide layer such as a magnesium-doped GaN layer formed on the p side. Preferably, a magnesium-doped AlGaN layer is formed. In this way, when the active layer is sandwiched between the guide layers or a magnesium-doped AlGaN layer is formed, it is formed between the active layer and the guide layer, and the undoped crystal layer is formed so as to be close to the active layer, Impurities are prevented from diffusing from the conductive layer to the active layer. The active layer may be composed of a single bulk active layer, but a quantum well such as a single quantum well (SQW) structure, a double quantum well (DQW) structure, or a multiple quantum well (MQW) structure. A structure may be formed. In the quantum well structure, a barrier layer is used in combination for separating the quantum well as necessary. Similarly, when such a quantum well structure is formed, the undoped crystal layer is formed close to the active layer to prevent impurities from diffusing from the conductive type layer to the active layer.
[0030]
For example, when the active layer is an InGaN layer, the structure is easy to manufacture, especially in the manufacturing process, and the light emission characteristics of the device can be improved. Furthermore, the InGaN layer is particularly easy to crystallize in the growth on the S plane, which is a structure in which nitrogen atoms are not easily desorbed, so that the crystallinity is good and the luminous efficiency can be increased. In the semiconductor light emitting device according to the present invention, an undoped crystal layer such as an undoped GaN layer is formed in the vicinity of the active layer, and the undoped crystal layer can prevent the impurities of the conductive layer from diffusing into the active layer. Therefore, it is possible to increase the concentration of impurities doped in the conductive type layer and further increase the light emission efficiency. Nitride-based compound semiconductors have the property of becoming n-type due to nitrogen vacancies formed in the crystal even when undoped, but carriers are usually added by doping donor impurities such as Si, Ge, and Se during crystal growth. The n-type having a preferable concentration can be obtained. The undoped crystal layer has similar properties, but the carrier concentration of the undoped crystal layer may be doped as long as impurities are not diffused and deteriorated in the active layer. In addition, the nitride compound semiconductor can be made p-type by doping the crystal with acceptor impurities such as Mg, Zn, C, Be, Ca, Ba. In order to form a p-type layer having a high carrier concentration, it is preferable to perform annealing at 400 ° C. or higher in an inert gas atmosphere such as nitrogen or argon after doping with acceptor impurities. Electron beam irradiation, microwave irradiation, light irradiation There is also a method to activate by such as.
[0031]
The first conductivity type layer, the active layer, the second conductivity type layer, and the undoped crystal layer are formed to extend in a plane parallel to the tilted crystal plane inclined with respect to the main surface of the substrate. The inward extension can be easily performed if the crystal is continuously grown where the inclined crystal plane is formed. For example, when the crystal layer has a substantially hexagonal pyramid shape or a substantially triangular prism shape, and each inclined crystal plane is an S plane or the like, the first conductivity type layer, the active layer, the second conductivity type layer, and the undoped crystal layer are all included. Or it can form on a part of S surface. By emitting light using the inclined S-plane, light is attenuated by multiple reflections on the parallel plate, but if there is an inclined plane, the light can escape the influence of multiple reflections and go out of the semiconductor. There is an advantage. Further, light extraction can be improved if the surface is not perpendicular to the substrate. The first conductivity type layer, that is, the clad layer can be made of the same material and the same conductivity type as the crystal layer constituting the S plane, and is formed while continuously adjusting the concentration after forming the crystal layer constituting the S plane. can do. As another example, a structure in which a part of the crystal layer constituting the S plane functions as the first conductivity type layer may be used. Similarly, when forming the active layer, each source can be switched and the concentration can be continuously adjusted. However, it is necessary to switch each source sharply. However, when an undoped crystal layer is formed in the vicinity of the active layer, the undoped crystal layer may contain impurities to the extent that impurities do not diffuse into the active layer, so the concentration is continuously adjusted from the first conductivity type layer, There is no need to adjust the concentration sharply.
[0032]
In the semiconductor light emitting device of the present invention, the first conductivity type layer, the active layer, and the second conductivity type layer extend in a plane parallel to the tilted crystal plane in the crystal layer having the tilted crystal plane tilted with respect to the main surface of the substrate. The semiconductor light-emitting device is formed in such a manner that an undoped crystal layer is formed in the vicinity of the active layer. Therefore, impurities diffusing from the conductive type layer to the active layer can be blocked by the undoped crystal layer, and deterioration of the active layer can be prevented without lowering the crystal quality of the active layer. Since the impurity diffusing from the conductive type layer to the active layer can be blocked by the undoped crystal layer, more light can be doped into the conductive type layer to increase the light emission efficiency of the semiconductor light emitting device. Further, as impurities are diffused from the conductive type layer to the active layer, a non-designed diffusion current is generated and a leakage current is generated. However, by forming an undoped crystal layer in the vicinity of the active layer, Impurities can be prevented from diffusing into the active layer, and a diffusion current that is a leakage current can be prevented.
[0033]
Furthermore, in the semiconductor light emitting device of the present invention, the light emission efficiency can be increased by utilizing the good crystallinity of the inclined inclined crystal plane. In particular, when current is injected only into the S-plane with good crystallinity, the S-plane has good In incorporation and crystallinity, so that the luminous efficiency can be increased. Further, the area extending in a plane parallel to the substantial S plane of the active layer can be larger than the area when the active layer is projected onto the main surface of the substrate or the underlying growth layer. By increasing the area of the active layer, the light emitting area of the element is increased, the current density can be reduced, and the luminance saturation can be reduced, thereby increasing the light emission efficiency. Therefore, when the undoped crystal layer is formed close to the active layer, the luminous efficiency can be further improved.
[0034]
When forming the first conductivity type layer, the active layer, and the second conductivity type layer in a plane parallel to the tilted inclined crystal plane, it is difficult to form a uniform impurity concentration in the conductivity type layer. Therefore, the conductivity type layer is uniformly doped by precisely controlling the impurity concentration to be doped. However, even if the impurity concentration is precisely controlled, there is a limit due to its three-dimensional structure. Generally, since the impurity concentration is not uniform, a concentration gradient is generated, and the conductivity type layer and the active layer are associated with the concentration gradient. Leakage current is generated at the interface. Therefore, by forming an undoped crystal layer in the vicinity of the active layer, it is possible to avoid the occurrence of a leak current at the interface on the active layer side, and to reduce the controllability of the impurity concentration. In addition, since it is difficult to form a crystal layer while making the film thickness uniform within the plane of the inclined tilted crystal plane, it is difficult to form an active layer or a conductive type layer with a uniform film thickness. Uneven brightness is likely to occur without showing the light emission characteristics. When the undoped crystal layer is formed in the vicinity of the active layer, such non-uniformity in film thickness can be alleviated and luminance unevenness can be reduced.
[0035]
As described above, in the semiconductor light emitting device of the present invention, the semiconductor light emitting device in which the first conductive type layer, the active layer, and the second conductive type layer are formed in a plane parallel to the inclined crystal plane inclined with respect to the main surface of the substrate. By forming an undoped crystal layer close to the active layer, it is possible to prevent the active layer from deteriorating by blocking the diffusion of impurities from the conductive type layer to the active layer. The generation of leakage current due to the non-uniformity of the film thickness can be avoided, and uneven brightness due to non-uniform film thickness can be reduced. Furthermore, the active layer formed in a plane parallel to the inclined crystal plane has a good crystallinity and a large effective area due to the structure of the semiconductor light emitting device, so that impurities are diffused from the conductive type layer to the active layer by the undoped crystal layer. Alternatively, a semiconductor light emitting device with higher luminous efficiency can be formed by doping a conductive type layer with many impurities.
[0036]
[First embodiment]
A semiconductor light-emitting device formed by selective growth and including a crystal layer of a hexagonal pyramid having a substantially triangular cross section having an S plane as an inclined crystal plane inclined with respect to the main surface of the substrate will be described with reference to FIGS. However, it demonstrates with the manufacturing process.
[0037]
First, the base growth layer 11 is formed on the substrate 10, and the mask layer 12 is formed on the base growth layer 11. As an example, an undoped GaN layer and a silicon-doped GaN layer are formed on a sapphire substrate having a C-plane as a main surface, and a mask layer 12 made of a silicon oxide film is formed by a sputtering method or the like.
[0038]
After forming the base growth layer 11 and the mask layer 12 on the substrate 10 in this way, a part of the mask layer 12 is removed to form an opening 13 (FIG. 1). The opening 13 can be formed using, for example, photolithography and hydrofluoric acid-based etchant. In FIG. 1, the shape of the opening 13 is a hexagonal shape, but any shape that can form a hexagonal pyramidal crystal layer such as a circular shape may be used. Further, the size of the opening 13 can be changed according to the characteristics of the semiconductor light emitting device.
[0039]
As shown in FIG. 2, the first conductivity type layer 14 is grown from the hexagonal opening 13 using selective growth. First, the underlying growth layer 11 grows from the opening 13 and continues to grow for a while. The undergrowth growth layer 11 having a hexagonal pyramid shape whose periphery is an S plane ({1-101}) is exposed. A hexagonal pyramid shape is formed when the growth conditions such as lack of growth time are different. However, by controlling the growth time, the hexagonal pyramid covered with the S surface is formed almost entirely within the frame of the opening 13 and has a substantially triangular cross section. A first conductivity type layer 14 having a hexagonal pyramid shape is formed.
[0040]
As shown in FIG. 3, the lower undoped crystal layer 15 is formed on the first conductivity type layer 14, and the active layer 16, the upper undoped crystal layer 17, and the second conductivity type layer 18 are sequentially formed thereon. . The crystal layer formed on the first conductivity type layer 14 is a hexagonal pyramid-shaped crystal layer having a substantially triangular cross section, and the inclined surface which is the side surface of the hexagonal pyramid-shaped crystal layer is an S plane ({1-101} plane) ) Or {11-22} plane, and is stably formed during selective growth.
[0041]
The first conductivity type layer 14 and the second conductivity type layer 18 function as a cladding layer, and the active layer 16 functions as a layer that generates light of the semiconductor light emitting device. The lower undoped crystal layer 15 prevents impurities doped in the first conductivity type layer 14 from diffusing into the active layer 16, and the upper undoped crystal layer 17 activates impurities doped in the second conductivity type layer 18. Prevents diffusion into layer 16. In particular, in an element having a three-dimensional structure such as a hexagonal pyramid, the diffusion of impurities from the second conductivity type layer 18 to the active layer 16 is severe, so that the impurities are formed in the active layer 16 by forming the upper undoped crystal layer 17. Diffusion can be prevented. Thus, by forming the lower undoped crystal layer 15 and the upper undoped crystal layer 17, impurities are not diffused into the active layer 16, and the active layer 16 is deteriorated without deteriorating the crystal quality of the active layer 16. Can be prevented.
[0042]
Both the lower undoped crystal layer 15 and the upper undoped crystal layer 17 may be formed close to the active layer 16, or one of them may be formed. In the case of forming one, since the diffusion of impurities from the second conductivity type layer 18 is severe, it is preferable to form the upper undoped crystal layer 17. As an example, the first conductivity type layer 14 is a silicon-doped GaN layer, the second conductivity type layer 18 is a magnesium-doped GaN layer, the active layer 16 is an InGaN layer, the lower undoped crystal layer 15 and the upper undoped crystal layer 17 are undoped. GaN layer. The film thickness of the upper undoped crystal layer 15 and the lower undoped crystal layer 17 formed in the vicinity of the active layer is preferably 10 to 100 nm. This is because when the film thickness is smaller than 10 mm, the carrier injection efficiency is increased, but the crystallinity of the active layer 16 and the second conductivity type layer 18 formed on the undoped crystal layer is decreased, and the light emission efficiency is decreased. If the film thickness is larger than 100 nm, the crystallinity of the active layer 16 and the second conductivity type layer 18 formed on the undoped crystal layer increases, but the carrier injection efficiency decreases and the light emission efficiency decreases. is there. The lower undoped crystal layer 15 and the upper undoped crystal layer 17 may be doped with impurities to the extent that they do not diffuse into the active layer 16 and deteriorate. Impurities doped into the second conductivity type layer 18 include zinc and beryllium.
[0043]
Although the active layer 16 can be composed of a single bulk active layer, a quantum well structure such as a single quantum well (SQW) structure, a double quantum well (DQW) structure, a multiple quantum well (MQW) structure, etc. May be formed. In the quantum well structure, a barrier layer is used in combination for separating the quantum well as necessary. It is also possible to form a multi-layer structure by forming guide layers such as GaN on both sides of the active layer 16, but the guide layer and the active layer 16 such as a magnesium-doped GaN layer and an InGaN layer formed on the p side. A magnesium-doped AlGaN layer is preferably formed between them. Thus, when the active layer 16 is sandwiched between the guide layers or a magnesium-doped AlGaN layer is formed, the lower undoped crystal layer 15 and the upper undoped crystal layer 17 are formed so as to be close to the active layer 16 and impurities Is prevented from diffusing into the active layer 16 and degrading the active layer 16.
[0044]
When the first conductive type layer 14, the active layer 16, and the second conductive type layer 18 are formed on the substrate 10 so as to extend in a plane parallel to the inclined crystal plane inclined with respect to the main surface of the substrate 10, From the three-dimensional structure, it is necessary to rapidly and continuously adjust the concentration of the impurity growth gas, but when the lower undoped crystal layer 15 and the upper undoped crystal layer 17 are formed close to the active layer 16, Since the lower undoped crystal layer 15 and the upper undoped crystal layer 17 may be doped with impurities that do not degrade the active layer 16, it is not necessary to switch the growth gas rapidly.
[0045]
As shown in FIG. 4, the p-side electrode 19 is formed on the second conductivity type layer 18 that is the outermost layer. The p-side electrode 19 is an electrode layer having, for example, a Ni / Pt / Au electrode structure or a Ni (Pd) / Pt / Au electrode structure, and is formed with high accuracy by a vapor deposition method or the like.
[0046]
As shown in FIG. 5, after forming the p electrode 19, the main surface of the substrate 10 is separated by reactive ion etching or dicer to form an element isolation groove 20, and the element is separated on the substrate 10 for each element. To do. For example, when forming an element isolation groove by reactive ion etching, a silicon oxide film or the like serving as a protective film for preventing erosion by dry etching is formed on the entire surface of the crystal layer by plasma CVD or the like, and then reactive ion etching is performed. Etching is performed, and the protective film is removed with an acid or the like to form the element isolation trench 20.
[0047]
Next, an element portion is peeled from the substrate 10 using an excimer laser, a YAG laser, or the like. When the laser is irradiated from the back surface of the substrate 10, ablation occurs at the interface between the base growth layer 11 and the substrate 10. As a result, the crystal layer can be peeled off from the substrate 10. For example, when the substrate 10 is a sapphire substrate, the underlying growth layer 11 is GaN, and an excimer laser is irradiated from the back surface, GaN is decomposed into metallic gallium and nitrogen at the interface between the sapphire substrate and the GaN layer, and easily from the sapphire substrate. The GaN layer can be peeled off.
[0048]
Ti / Al / Pt / Au electrodes are accurately deposited on the back side of the element (FIG. 6). This electrode functions as the n-side electrode 21 disposed on the back surface of the element. The n-side electrode 21 disposed on the back surface of the element is preferably disposed at the corner as much as possible so as not to block light emitted from the back surface. Further, when the base growth layer 11 includes an undoped base growth layer and a doped base growth layer, the electrode is deposited after the undoped base growth layer is removed by wet etching to form the n-side electrode 21. .
[0049]
Thus, in the semiconductor light emitting device in which the lower undoped crystal layer 15 and the upper undoped crystal layer 17 are formed in the vicinity of the active layer 16, impurities are introduced into the active layer 16 from the first conductivity type layer 14 and the second conductivity type layer 18. Is not diffused and deterioration of the active layer 16 can be prevented without lowering the crystal quality of the active layer 16. Further, since the diffusion of impurities into the active layer 16 can be prevented, the emission efficiency of the semiconductor light emitting device is improved by doping more impurities into the first conductivity type layer 14 and the second conductivity type layer 18. Can do.
[0050]
[Second Embodiment]
A semiconductor light-emitting element formed by selective growth and including a triangular prism-shaped crystal layer having a substantially triangular cross section having an S plane as an inclined crystal plane inclined with respect to the main surface of the substrate will be described with reference to FIGS. However, it demonstrates with the manufacturing process.
[0051]
First, the base growth layer 31 is formed on the substrate 30, and the mask layer 32 is formed on the base growth layer 31. As an example, an undoped GaN layer and a silicon-doped GaN layer are formed on a sapphire substrate having a C-plane as a main surface, and a mask layer made of a silicon oxide film is formed by a sputtering method or the like.
[0052]
After forming the base growth layer 31 and the mask layer 32 on the substrate 30 in this way, a part of the mask layer 32 is removed to form an opening 33 (FIG. 7). The opening 33 can be formed using, for example, photolithography and a hydrofluoric acid etchant. The shape of the opening 33 is a stripe shape, and the longitudinal direction thereof is the [1-100] direction or the [11-20] direction. By extending the shape of the opening 33 in a [1-100] direction or [11-20] direction as a stripe shape, an S-plane is formed as an inclined crystal plane inclined with respect to the main surface of the substrate 30, and the ridge line 35 is formed. A triangular columnar crystal layer in the direction of the opening 33 can be formed. Further, the size of the opening 33 can be changed from the longitudinal direction to the characteristics of the semiconductor light emitting device.
[0053]
As shown in FIG. 8, the first conductivity type layer 34 is grown from the stripe-shaped opening 33 using selective growth. First, the underlying growth layer 31 is inclined from the opening 33 when the growth continues for a while. The crystal plane is the S plane, the ridge line 35 direction is the [1-100] direction or the [11-20] direction, and the inclined planes formed on both sides of the ridge line 35 are the S plane ({1-101} plane) or {11 A triangular pillar-shaped base growth layer 31 that is a −22} plane is exposed, and a first conductivity type layer 34 is formed.
[0054]
As shown in FIG. 8, a lower undoped crystal layer 36 is formed on the first conductivity type layer 34, and an active layer 37, an upper undoped crystal layer 38, and a second conductivity type layer 39 are formed thereon. . These layers are triangular prism-shaped crystal layers having a substantially triangular cross section, the ridge line 35 is in the [1-100] direction or [11-20] direction, and the inclined surfaces formed on both sides of the ridge line 35 are S planes. ({1-101} plane) or {11-22} plane, and is stably formed during selective growth.
[0055]
The first conductivity type layer 34 and the second conductivity type layer 39 function as a cladding layer, and the active layer 37 functions as a layer that generates light of the semiconductor light emitting device. The lower undoped crystal layer 36 prevents impurities doped in the first conductivity type layer 34 from diffusing into the active layer 37, and the upper undoped crystal layer 38 activates impurities doped in the second conductivity type layer 39. Prevents diffusion into layer 37. In particular, in an element having a three-dimensional structure called a triangular prism, since the diffusion of impurities from the second conductivity type layer 39 to the active layer 37 is severe, the impurities are diffused into the active layer 37 by forming the upper undoped crystal layer 38. Can be prevented. In this way, by forming the lower undoped crystal layer 36 and the upper undoped crystal layer 38, impurities are not diffused into the active layer 37, and the active layer 37 is deteriorated without deteriorating the crystal quality of the active layer 37. Can be prevented.
[0056]
Both the lower undoped crystal layer 36 and the upper undoped crystal layer 38 may be formed close to the active layer 37, or one of them may be formed. In the case of forming one, since the diffusion of impurities from the second conductivity type layer 39 is intense, it is preferable to form the upper undoped crystal layer 38. As an example, the first conductivity type layer 34 is a silicon-doped GaN layer, the second conductivity type layer 39 is a magnesium-doped GaN layer, the active layer 37 is an InGaN layer, the lower undoped crystal layer 36 and the upper undoped crystal layer 38 are undoped. GaN layer. The film thickness of the upper undoped crystal layer 36 and the lower undoped crystal layer 38 is preferably 10 to 100 nm. This is because when the film thickness is smaller than 10 mm, the carrier injection efficiency is increased, but the crystallinity of the active layer 37 and the second conductivity type layer 39 formed on the undoped crystal layer is decreased, and the light emission efficiency is decreased. When the film thickness is larger than 100 nm, the crystallinity of the active layer 37 and the second conductivity type layer 39 formed on the undoped crystal layer is increased, but the carrier injection efficiency is decreased and the light emission efficiency is decreased. is there. Further, the lower undoped crystal layer 36 and the upper undoped crystal layer 38 may be doped with impurities to the extent that they do not diffuse into the active layer 37 and deteriorate. Impurities doped into the second conductivity type layer 39 include zinc and beryllium.
[0057]
Although the active layer 37 can be composed of a single bulk active layer, a quantum well structure such as a single quantum well (SQW) structure, a double quantum well (DQW) structure, a multiple quantum well (MQW) structure, etc. May be formed. In the quantum well structure, a barrier layer is used in combination for separating the quantum well as necessary. It is also possible to form a multi-layer structure by forming guide layers such as GaN on both sides of the active layer 37, but the guide layer and the active layer 37, such as a magnesium-doped GaN layer and an InGaN layer, formed on the p side. A magnesium-doped AlGaN layer is preferably formed between them. As described above, when the active layer 37 is sandwiched between the guide layers or a magnesium-doped AlGaN layer is formed, the lower undoped crystal layer 36 and the upper undoped crystal layer 38 are formed so as to be close to the active layer 37, and impurities Is prevented from diffusing into the active layer 37 and degrading the active layer 37.
[0058]
When the first conductivity type layer 34, the active layer 37, and the second conductivity type layer 39 are formed on the substrate 30 so as to extend in a plane parallel to the inclined crystal plane inclined with respect to the main surface of the substrate 30, From the three-dimensional structure, it is necessary to rapidly and continuously adjust the concentration of the impurity growth gas, but when the lower undoped crystal layer 36 and the upper undoped crystal layer 38 are formed close to the active layer 37, Since the lower undoped crystal layer 36 and the upper undoped crystal layer 38 may be doped with impurities that do not deteriorate the active layer, it is not necessary to make the switching of the growth gas steep.
[0059]
As shown in FIG. 10, the p-side electrode 40 is formed on the second conductivity type layer 39 which is the outermost layer. The p-side electrode 40 is an electrode layer having a laminated structure of, for example, Ni / Pt / Au or laser / Pt / Au, and is formed by a vapor deposition method or the like.
[0060]
As shown in FIG. 5, after forming the p-side electrode 40, the main surface of the substrate 30 is separated by reactive ion etching or dicer to form element isolation grooves 41, and the elements are separated on the substrate 30. do. For example, when forming an element isolation groove by reactive ion etching, a silicon oxide film or the like serving as a protective film for preventing erosion by dry etching is formed on the entire surface of the crystal layer by plasma CVD or the like, and then reactive ion etching is performed. Etching is performed, and the protective film is removed with an acid or the like to form the element isolation trench 41.
[0061]
Next, an element portion is peeled from the substrate 30 using an excimer laser, a YAG laser, or the like. When the laser is irradiated from the back surface of the substrate 30, ablation occurs at the interface between the base growth layer 31 and the substrate 30. As a result, the crystal layer can be separated from the substrate 30. For example, when the substrate 30 is a sapphire substrate, the underlying growth layer 31 is GaN, and an excimer laser is irradiated from the back surface, GaN is decomposed into metallic gallium and nitrogen at the interface between the sapphire substrate and the GaN layer, and easily from the sapphire substrate. The GaN layer can be peeled off.
[0062]
Ti / Al / Pt / Au electrodes are accurately deposited on the back side of the device (see figure). 12 ). This electrode functions as an n-side electrode 42 disposed on the back surface of the element. The n-side electrode 42 disposed on the back surface of the element is preferably disposed at the corner as much as possible so as not to block light emitted from the back surface. When the base growth layer 31 is composed of an undoped base growth layer and a doped base growth layer, the electrode is deposited after the undoped base growth layer is removed by wet etching to form the n-side electrode 42. .
[0063]
In addition, the semiconductor light emitting element separated for each element by the element isolation groove 41 can be cleaved substantially perpendicularly to the direction of the stripe-shaped ridge 35 to form a cleaved surface that becomes a resonance surface of the semiconductor laser element. it can.
[0064]
In the semiconductor light emitting device in which the lower undoped crystal layer 36 and the upper undoped crystal layer 38 are formed in the vicinity of the active layer 37 as described above, the first conductivity type layer 34 and the second conductivity type layer 34 and the second undoped crystal layer 38 are formed as in the first embodiment. Impurities are not diffused from the conductive type layer 39 to the active layer 37, and deterioration of the active layer 37 can be prevented without lowering the crystal quality of the active layer 37. Furthermore, since the diffusion of impurities into the active layer 37 can be prevented, the emission efficiency of the semiconductor light emitting device is improved by doping more impurities into the first conductivity type layer 34 and the second conductivity type layer 39. Can do.
[0065]
【The invention's effect】
In the semiconductor light emitting device of the present invention, the active layer is formed in a plane parallel to the tilted crystal plane and has high crystallinity and a large effective area, so that the light emission efficiency is high, but the undoped crystal layer formed close to the active layer As a result, the impurities are prevented from diffusing from the conductive layer to the active layer. Therefore, the light emitting efficiency can be further improved by doping the conductive layer more with impurities. Further, when the undoped crystal layer is formed close to the active layer, unevenness in luminance due to the diffusion of impurities at the interface between the active layer and the conductive type layer and the unevenness of the leakage current and the non-uniform thickness of the impurity concentration. Thus, a semiconductor light emitting device having a long lifetime and excellent light emission characteristics can be formed. In addition, since leakage current and luminance unevenness can be avoided in this way, a semiconductor light emitting element with low design tolerance, long life, and good reproducibility can be efficiently formed.
[Brief description of the drawings]
FIG. 1 is a process perspective view showing formation of a mask layer and an opening in a manufacturing process of a semiconductor light emitting device according to an embodiment of the present invention.
FIG. 2 is a process perspective view showing the formation of a first conductivity type layer in the manufacturing process of the semiconductor light emitting device according to the embodiment of the present invention.
FIG. 3 is a process perspective view showing the formation of an undoped crystal layer, an active layer, and a second conductivity type layer in the manufacturing process of the semiconductor light emitting device of the embodiment of the present invention.
FIG. 4 is a process perspective view showing formation of a p-side electrode in a manufacturing process of a semiconductor light emitting device according to an embodiment of the present invention.
FIG. 5 is a process perspective view showing formation of an element isolation groove in a manufacturing process of a semiconductor light emitting element according to an embodiment of the present invention.
FIG. 6 is a process perspective view showing the formation of an n-side electrode in the manufacturing process of the semiconductor light emitting device according to the embodiment of the present invention.
FIG. 7 is a process perspective view showing formation of a mask layer and an opening in the manufacturing process of the semiconductor light emitting device according to the embodiment of the present invention.
FIG. 8 is a process perspective view showing the formation of a first conductivity type layer in the manufacturing process of the semiconductor light emitting device according to the embodiment of the present invention.
FIG. 9 is a process perspective view showing formation of an undoped crystal layer, an active layer, and a second conductivity type layer in the manufacturing process of the semiconductor light emitting device according to the embodiment of the present invention.
FIG. 10 is a process perspective view showing the formation of the p-side electrode in the manufacturing process of the semiconductor light emitting device according to the embodiment of the present invention.
FIG. 11 is a process perspective view showing formation of an element isolation groove in a manufacturing process of a semiconductor light emitting element according to an embodiment of the present invention.
FIG. 12 is a process perspective view showing the formation of an n-side electrode in the manufacturing process of the semiconductor light emitting device according to the embodiment of the present invention.
[Explanation of symbols]
10,30 substrate
11, 31 Underground growth layer
12, 32 Mask layer
13,33 opening
14, 34 First conductivity type layer
15, 36 Lower undoped crystal layer
16, 37 active layer
17.38 Upper undoped crystal layer
18, 39 Second conductivity type layer
19, 40 p-side electrode
20, 41 element isolation groove
21, 42 n-side electrode
35 Ridge line

Claims (25)

A substrate,
A crystal layer having an inclined crystal plane tilted from the principal plane of the substrate formed on said substrate,
A first conductivity type layer, an active layer, and a second conductivity type layer extending in a plane parallel to the inclined crystal plane formed in the crystal layer ;
A first electrode formed on the second conductivity type layer;
An undoped crystal extending in a plane parallel to the inclined crystal plane formed between at least one of the active layer and the first conductivity type layer and between the active layer and the second conductivity type layer. Layers ,
And a second electrode formed in a plane parallel to the main surface of the substrate .   2. The semiconductor light emitting device according to claim 1, wherein the crystal layer is made of a wurtzite type compound semiconductor layer.   3. The semiconductor light emitting device according to claim 2, wherein the wurtzite compound semiconductor layer is a nitride compound semiconductor layer.   2. The semiconductor light emitting device according to claim 1, wherein the crystal layer is formed by selective growth on the substrate through a base growth layer.   5. The semiconductor light emitting device according to claim 4, wherein the selective growth is performed using an opening of a selectively formed mask layer.   5. The semiconductor light emitting device according to claim 4, wherein the selective growth is performed such that the crystal layer extends laterally from the opening.   The semiconductor light emitting element according to claim 1, wherein a main surface of the substrate is a C plane.   2. The semiconductor light emitting element according to claim 1, wherein the inclined crystal plane includes at least one of an S plane and a (11-22) plane.   2. The semiconductor light emitting device according to claim 1, wherein the crystal layer has a hexagonal pyramid shape or a triangular stripe shape.   The semiconductor light emitting device according to claim 9, wherein the triangular stripe-shaped ridge line is in a [1-100] direction or a [11-20] direction.   2. The semiconductor light emitting device according to claim 1, wherein the second conductivity type layer is doped with magnesium, zinc, or beryllium.   2. The semiconductor light emitting device according to claim 1, wherein the undoped crystal layer has a thickness of 10 to 100 nm. Forming a mask layer or crystalline seed layer with an opening on a substrate,
The crystal layer having an inclined inclined crystal plane is selectively formed to the main surface of the substrate from the opening or the crystal seed layer,
Forming a first conductivity type layer, an active layer, and a second conductivity type layer extending in a plane parallel to the inclined crystal plane in the crystal layer;
Forming a first electrode on the second conductivity type layer;
An undoped crystal layer extending in a plane parallel to the inclined crystal plane is formed between at least one of the active layer and the first conductivity type layer and between the active layer and the second conductivity type layer. And
A method of manufacturing a semiconductor light emitting device, comprising forming a second electrode in a plane parallel to a main surface of the substrate .   14. The method of manufacturing a semiconductor light emitting device according to claim 13, wherein the crystal layer is made of a wurtzite compound semiconductor layer.   15. The method of manufacturing a semiconductor light emitting device according to claim 14, wherein the wurtzite type compound semiconductor layer is a nitride compound semiconductor layer.   The method of manufacturing a semiconductor light emitting element according to claim 13, wherein the crystal layer is formed on the substrate through an underlying growth layer.   14. The method of manufacturing a semiconductor light emitting element according to claim 13, wherein the crystal layer is grown in a lateral direction wider than the opening.   The method of manufacturing a semiconductor light emitting element according to claim 13, wherein a main surface of the substrate is a C plane.   14. The method of manufacturing a semiconductor light emitting element according to claim 13, wherein the inclined crystal plane includes at least one of an S plane and a (11-22) plane.   The method of manufacturing a semiconductor light emitting element according to claim 13, wherein the crystal layer has a hexagonal pyramid shape or a triangular stripe shape.   21. The method of manufacturing a semiconductor light-emitting element according to claim 20, wherein the triangular stripe-shaped ridge line is in a [1-100] direction or a [11-20] direction.   The method according to claim 13, wherein the second conductivity type layer is doped with magnesium, zinc, or beryllium.   14. The method of manufacturing a semiconductor light emitting element according to claim 13, wherein the undoped crystal layer has a thickness of 10 to 100 nm.   14. The method of manufacturing a semiconductor light emitting element according to claim 13, wherein a plurality of semiconductor light emitting elements are formed on the substrate and then separated for each semiconductor light emitting element.   25. The method of manufacturing a semiconductor light emitting device according to claim 24, wherein one electrode is formed on the back surface of the separated semiconductor light emitting device.

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