JP4100493B2 - Semiconductor device including boron phosphide semiconductor layer, method for manufacturing the same, light emitting diode, and boron phosphide semiconductor layer - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a crystal structure of a boron phosphide-based semiconductor layer that is suitable for obtaining a boron phosphide-based semiconductor element formed on a silicon (Si) single crystal (silicon) substrate, and a boron phosphide-based system including the same. The present invention relates to a semiconductor element.
[0002]
[Prior art]
Conventionally, a light emitting diode (LED) or a laser diode (LD) using boron phosphide (BP) which is a kind of boron phosphide-based semiconductor containing boron (B) and phosphorus (P) as constituent elements. A technique for forming a semiconductor light emitting device such as the above is known (see US Pat. No. 6,069,021). A conventional boron phosphide-based semiconductor light-emitting device is configured using, for example, a stacked structure including a boron phosphide layer formed on a substrate made of silicon single crystal (silicon) as a buffer layer (the above-mentioned United States). (See Patent No. 6,069,021). Recently, a laminated structure for a semiconductor light emitting device having a light emitting part with a pn junction type double heterostructure having a wide band gap boron phosphide layer as a barrier (cladding) layer has also been invented (Japanese Patent Application No. 2001-2001). 158282).
[0003]
Conventionally, it has been found that a single crystal layer of boron phosphide having the same crystal plane as the crystal plane forming the substrate surface grows on the silicon substrate. For example, it is known that a boron phosphide single crystal layer composed of {100} crystal planes stacked in parallel to the substrate surface grows on a {100} -Si single crystal substrate whose surface is a {100} crystal plane. (Shono Katsufusa, “Semiconductor Technology (above)” (see June 25, 1992, 9th edition, The University of Tokyo Press, page 77). It is also known that a boron phosphide single crystal layer containing no twinning can be grown (see “Semiconductor Technology (above)” above, page 98), while {100} -boron phosphide single crystal containing twins It is also known that layers can be obtained (see “Semiconductor Technology (above)” above, pages 99-100).
[0004]
[Problems to be solved by the invention]
As disclosed in the prior art, the twins contained in the boron phosphide layer are said to have a feature that relaxes the mismatch rate between crystal lattices (the above-mentioned “Semiconductor Technology (above)”, page 100. reference). Therefore, the use of a boron phosphide-based semiconductor layer containing twins can contribute to obtaining an LED having excellent characteristics, for example, emission intensity. However, as disclosed in the prior art, it is difficult to stably obtain a boron phosphide-based semiconductor layer containing twins. In other words, the requirement for producing a boron phosphide-based semiconductor layer that stably contains twins has not been clarified so far. For example, there is a problem in stably obtaining a light-emitting element having excellent light emission intensity. Has come.
[0005]
An object of the present invention is to provide a boron phosphide-based semiconductor layer having a crystal structure capable of stably including twins. In addition, the present invention provides a boron phosphide-based semiconductor element having improved characteristics by including a polycrystalline boron phosphide-based semiconductor layer that stably includes twins having a specific crystal direction as a twin plane. . Here, the boron phosphide-based semiconductor layer having a crystal structure which is the object of the present invention is not composed of a conventional film-like single crystal but a twin interface (twin plane) (by CW Van). Boron phosphide system composed of polycrystals formed by assembling single crystals with different crystal directions in "Chemical Crystallography" (June 15, 1970, published by Baifukan Co., Ltd., first edition, pages 75-76) It is a semiconductor layer.
[0006]
[Means for Solving the Problems]
That is, the present invention provides (1) a boron phosphide-based semiconductor having a substrate made of silicon (Si) single crystal and a crystal plane that is formed on the surface of the substrate and that is the same as the crystal plane constituting the surface of the substrate. In a boron phosphide-based semiconductor element comprising a boron phosphide-based semiconductor layer made of crystals, the substrate is made of a {111} -Si single crystal whose surface is a {111} crystal plane, The boron phosphide-based semiconductor layer has a bottom surface made of a {111} crystal face of a boron phosphide-based semiconductor crystal arranged in parallel to the {111} crystal face of the substrate, and is surrounded by a plane equivalent to the {111} crystal face. MultiplethreeIt is composed of a polycrystalline layer in which single crystal bodies of pyramidal boron phosphide-based semiconductor crystals are assembled, and the single crystal bodies are twinned at an angle of 60 degrees with respect to the <110> crystal direction of the substrate. A boron phosphide-based semiconductor element having a crystal interface. It is.
[0007]
The present invention also provides
(2) It has a heterogeneous (hetero) junction formed by laminating a group III-V compound semiconductor layer on the boron phosphide-based semiconductor layer, and the group III-V compound semiconductor layer is composed of a boron phosphide-based semiconductor layer. The boron phosphide system according to the above (1), characterized in that the boron phosphide system is composed of crystal planes arranged at intervals corresponding to the plane spacing (lattice spacing) of crystal planes intersecting the surface of the single crystal forming the semiconductor layer Semiconductor element.
(3) The boron phosphide-based material according to (1) or (2) above, wherein the single crystal body of the boron phosphide-based semiconductor crystal comprises a monomeric boron phosphide crystal. Semiconductor element.
[0008]
The present invention also provides
(4) Growth rate of the boron phosphide-based semiconductor layer on the {111} -Si single crystal substrate by a metal organic pyrolysis vapor deposition method (MOCVD method) at a temperature of 950 ° C. to 1100 ° C. The method of manufacturing a boron phosphide-based semiconductor element according to any one of (1) to (3) above, wherein the step is formed at a rate of 20 nm to 60 nm per minute.
(5) Growth rate of the boron phosphide-based semiconductor layer on a {111} -Si single crystal substrate at a temperature of 1025 ° C. or higher and 1075 ° C. or lower by metal organic pyrolysis vapor deposition (MOCVD). Is formed at a rate of 30 nm to 40 nm per minute. The method of manufacturing a boron phosphide-based semiconductor element according to (4) above, wherein
It is.
[0009]
The present invention also provides
(6) A light-emitting diode comprising the boron phosphide-based semiconductor element as described in (1) to (3) above.
It is.
[0010]
  The present invention also provides (7) phosphide comprising a boron phosphide-based semiconductor crystal formed on the surface of a substrate made of silicon (Si) single crystal and having the same crystal plane as that constituting the surface of the substrate. In the boron-based semiconductor layer, the substrate is made of a {111} -Si single crystal whose surface is a {111} crystal plane, and the boron phosphide-based semiconductor layer is formed on the {111} crystal plane of the substrate. A plurality of boron phosphide-based semiconductor crystals arranged in parallel, each having a bottom surface made of a {111} crystal plane and surrounded by a plane equivalent to the {111} crystal plane;threeIt is composed of a polycrystalline layer in which single crystal bodies of pyramidal boron phosphide-based semiconductor crystals are assembled, and the single crystal bodies are twinned at an angle of 60 degrees with respect to the <110> crystal direction of the substrate. A boron phosphide-based semiconductor layer having a crystal interface. It is.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
In the present invention, the boron phosphide-based semiconductor layer can be suitably formed on a Si single crystal substrate having a {111} crystal plane as a surface (referred to as a {111} -Si single crystal substrate in this specification). Silicon atoms are present more densely in the {111} crystal plane of the diamond crystal structure type Si single crystal than in the {100} or {110} crystal plane. Therefore, the {111} -Si single crystal substrate has an advantage of suppressing the diffusion and penetration of the constituent elements of the boron phosphide-based semiconductor layer deposited thereon into the substrate, and is effective for forming a clear bonding interface. Play. In addition, the {111} -Si single crystal substrate having conductivity can be laid on the back surface with an ohmic electrode of either positive or negative polarity of either polarity, which is effective for, for example, simple construction of a light emitting device. Raised. In particular, a low resistivity (resistivity) conductive single crystal substrate with a resistivity of 1 milliohm (mΩ) or less, more preferably 0.1 mΩ or less, results in an LED with a low forward voltage (so-called Vf). To contribute. In addition, since it has excellent heat dissipation, it is effective in constructing an LD that provides stable oscillation.
[0012]
Preferably, the polycrystalline boron phosphide-based semiconductor layer laminated on the surface of the {111} -Si substrate contains boron (B) and phosphorus (P) as constituent elements._αAl_βGa_γIn_{1- α - β - γ}P_{1- δ}As_δLayers (0 <α ≦ 1, 0 ≦ β <1, 0 ≦ γ <1, 0 <α + β + γ ≦ 1, 0 ≦ δ <1). For example, B_αAl_βGa_γIn_{1- α - β - γ}P_{1- δ}N_δ(0 <α ≦ 1, 0 ≦ β <1, 0 ≦ γ <1, 0 <α + β + γ ≦ 1, 0 ≦ δ <1). Monomeric boron phosphide (BP) has the advantage that the constituent elements are only boron (B) and phosphorus (P), and the number of constituent elements is smaller than that of multi-element mixed crystals, so that film formation is easy. Therefore, it is particularly preferable. Also, for example, depending on the metal organic thermal decomposition vapor deposition (MOCVD) means, the growth rate is set to 2 nm or more and 30 nm or less per minute, and the supply ratio of group V elements such as phosphorus and group III elements such as boron (so-called so-called) Boron phosphide grown with a V / III ratio of 15 or more and 60 or less becomes a wide bandgap semiconductor with a forbidden band width of about 3 eV at room temperature. Such a boron phosphide semiconductor layer having a wide forbidden band can be used as, for example, a barrier layer for the light emitting layer in a light emitting element.
[0013]
  In the present invention, the polycrystalline boron phosphide-based semiconductor layer is formed by aggregating single crystal bodies made of a plurality of boron phosphide-based semiconductor crystals. The shape of a single crystal constituting the polycrystalline layer according to the present invention is schematically shown in FIG. Each single crystal body 13 on the {111} -Si single crystal substrate 11 is a positive surface having a periphery equivalent to the {111} crystal plane of the boron phosphide-based semiconductor crystal.threePyramid 13b or positivethreeThe top of the pyramid is the {111} crystal planethreeThe outer shape of the pyramid 13c is formed. The bottom surface 13a of each single crystal body 13 is composed of {111} crystal planes of a boron phosphide-based semiconductor crystal arranged in parallel to the {111} crystal plane of the {111} -Si single crystal substrate. The bottom surface 13 a is a crystal plane that is grounded to the surface of the {111} -Si single crystal substrate 11.
[0014]
  As shown in the schematic plan view of FIG.threeThe pyramid-shaped single crystal bodies 13 are coupled to each other. The single crystal bodies 13 are connected to each other through the joint surface 16. Twins 15 are present inside each single crystal body 13. Since the direction in which the twin planes 14 included in each single crystal body 13 exist is not uniformly uniform, each single crystal body 13 is composed of each single crystal body 13 containing twins in such different crystal directions. In the present invention, the boron phosphide-based semiconductor layer is referred to as a polycrystalline layer. In the present invention, in particular, the single crystal body 13 that regularly includes twin planes in the direction of 60 degrees (°) with respect to the <110> crystal direction of the {111} -Si single crystal forming the substrate is assembled. To form a polycrystalline layer. The twin plane referred to here is specifically a plane equivalent to the {111} crystal plane of the boron phosphide-based semiconductor crystal. That is, {111}, {−1. -1. -1. }, {1. -1.1. } Or the like. The twin plane isthreeIt is characterized by being parallel to any {111} crystal plane of the boron phosphide-based semiconductor crystal that forms the periphery of the pyramidal single crystal body 13. Due to the generation of twins 15 in which the {111} crystal plane of the boron phosphide-based semiconductor crystal is the twin plane 14, mismit dislocations due to lattice mismatch between the Si single crystal substrate and the boron phosphide-based semiconductor crystal Generation and propagation can be effectively suppressed. In a boron phosphide-based semiconductor crystal, twins having {111} crystal planes as twin planes can be formed more stably and easily than twins having twin planes as other crystal planes. . Therefore, if a polycrystalline layer is formed by assembling single crystal bodies containing twins having the {111} crystal plane of the boron phosphide-based semiconductor crystal as twin planes, the propagation of misfit dislocations is stably suppressed. Can be effective.
[0015]
The existence of twins is known, for example, from the presence or absence of anomalous diffraction spots on the electron diffraction pattern (pattern) imaged by the electron diffraction technique (Kosaka Saka, “Crystal Electron Microscopy”, 1997 11 May 25, Uchida Otsukaku, 1st edition, pages 111-113). Further, if an angle formed between a <110> crystal direction on a diffraction pattern obtained by imaging an incident electron beam as parallel to the <110> crystal direction of the boron phosphide-based semiconductor layer and a diffraction spot caused by a twin crystal, < 110> The angle formed by the crystal direction and twins can be known. Incidentally, twins can also be regarded as a kind of stacking fault (see “Crystal Electron Microscopy”, page 112 above).
[0016]
  In order to obtain a polycrystalline layer in which single crystals containing twins according to the present invention are assembled, it is necessary to precisely control the conditions during film formation. In particular, it consists of a boron phosphide-based semiconductor crystal containing twins with {111} crystal planes as twin planes.threeThe pyramidal single crystal is, for example, triethylboron ((C₂H_Five)_ThreeB) / phosphine (PH_Three) / Hydrogen (H₂) By using a metal organic thermal decomposition vapor deposition method (MOCVD method) at a normal pressure using a raw material system as a raw material system. In the MOCVD means, a temperature range suitable for obtaining a boron phosphide-based semiconductor polycrystalline layer, particularly a monomeric boron phosphide polycrystalline layer, is 950 ° C. or higher and 1100 ° C. or lower, more preferably 1025 ° C. It is the range of -1075 degreeC. A lower temperature of about 950 ° C. to about 1000 ° C. is suitable for forming a boron phosphide-based semiconductor polycrystalline layer containing indium (In). The boron phosphide-based semiconductor polycrystalline layer containing aluminum (Al) as a constituent element preferably has a relatively high temperature of about 1050 ° C. to 1100 ° C. At high temperatures exceeding about 1200 ° C, BP₆, B₁₃P₂Boron phosphide multimers such as the above are easily generated, which is inconvenient for obtaining a boron phosphide-based semiconductor layer that is homogeneous in composition.
[0017]
Further, in order to efficiently form a single crystal containing twins, it is desirable that the growth rate be in the range of 20 nm / min to 60 nm / min. For monomeric boron phosphide (BP), a growth rate of 30 nm to 40 nm per minute is particularly suitable. A single crystal grown at a speed exceeding 60 nm has a disadvantage that the density of other crystal defects such as point defects and dislocations rapidly increases in addition to a large amount of twins (stacking defects), and has excellent crystallinity. Difficulties in obtaining a polycrystalline layer. On the other hand, if the growth rate is reduced, that is, it takes a long time to obtain a boron phosphide-based semiconductor layer having a desired layer thickness, the chance of volatilization of the constituent element phosphorus (P) increases during growth. . For this reason, a small growth rate of less than 20 nm / min causes a rapid chemical equivalence ratio imbalance among the constituent elements of the boron phosphide-based semiconductor layer due to evaporation and volatilization of phosphorus (P). A boron phosphide-based compound semiconductor layer having a stoichiometrically unbalanced composition contains a large amount of point defects and is not suitable for a polycrystalline layer according to the present invention.
[0018]
The twins contained in the single crystal body suppress, for example, the propagation of misfit dislocations caused by the lattice mismatch between the Si single crystal of the substrate and the boron phosphide-based semiconductor constituting the single crystal body. Have For example, misfit dislocations generated from the bonding interface between the Si substrate and the single crystal are absorbed by twins existing inside the single crystal and have an action of suppressing further upward propagation. This reduces the density of threading dislocations that penetrate to the top of the single crystal.
[0019]
In order to obtain a single crystal with few misfit dislocations in the first place, a technical means of providing a buffer layer between the Si single crystal substrate and the boron phosphide-based semiconductor layer is also effective. The buffer layer is preferably composed of an amorphous or polycrystalline boron phosphide compound semiconductor layer. The amorphous or polycrystalline buffer layer is effective in relaxing the lattice mismatch with the Si single crystal that forms the substrate and producing a boron phosphide-based semiconductor layer with a low crystal defect density such as misfit dislocations. To do. In particular, when the buffer layer is composed of a boron phosphide-based semiconductor, boron and phosphorus act as “growth nuclei” that promote growth, so that a continuous boron phosphide-based semiconductor layer is formed thereon. There is an effect. When the buffer layer is composed of boron phosphide, the layer thickness is preferably about 1 nm to 50 nm, and more preferably 2 nm to 15 nm.
[0020]
The surface layer portion of the polycrystalline layer formed by assembling single crystals containing twins is a region having few misfit dislocations penetrating from the lower Si single crystal substrate side and having excellent crystallinity. Therefore, a deposited layer having excellent crystallinity can be grown on the boron phosphide-based semiconductor polycrystalline layer having the structure of the present invention. In particular, a crystal composed of crystal planes in which the deposited layer is arranged at the same spacing as the crystal lattice plane spacing (lattice spacing) intersecting the surface of the boron phosphide-based semiconductor single crystal forming the surface of the polycrystalline layer. When a layer is used, the effect can be improved in obtaining a crystal layer having few misfit dislocations and excellent crystallinity. As schematically shown in FIG. 3, the lower-order Miller index {hkl} plane intersecting the surface 17 made of the {111} crystal plane of the single crystal has {111} other than h = k = 1 = 1. , {110}, {100} crystal planes, and the like. The spacing (= d) of these {hkl} crystal plane single crystal bodies on the {111} crystal plane surface is d (Å) = in the case of a boron phosphide-based semiconductor crystal of a cubic zinc blende crystal. a / {(h²+ K²+ L²)^1/2Sin sin}}. a (Å) is a lattice constant of a boron phosphide-based semiconductor crystal, and θ is an angle (°) between the {111} crystal surface 17 and a crystal plane intersecting with it. For example, on the surface of a boron phosphide (BP) polycrystalline layer, the {110} crystal plane intersecting at right angles to the {111} crystal plane of the BP single crystal 13 constituting the surface and the lattice spacing (≈3.21Å) ), A wurtzite crystal type (Wurtzite) gallium nitride / indium mixed crystal (Ga) in which hexagonal (1.0.0.0.) Crystal planes are aligned._0.94In_0.06N) An example of depositing a crystal layer is given. Such a crystal layer having excellent crystallinity can be suitably used as, for example, a light-emitting layer in a light-emitting element that provides high-intensity light emission.
[0021]
If the boron phosphide-based semiconductor polycrystalline layer according to the present invention is used, for example, an LED can be configured as a boron phosphide-based semiconductor element. The LED is, for example, a p-type phosphide according to the present invention grown through a p-type {111} -Si single crystal substrate and an amorphous buffer layer containing boron (B) and phosphorus (P) on the substrate. A laminated structure comprising a boron (BP) polycrystalline layer, an n-type light emitting layer on the polycrystalline layer, and an n-type boron phosphide (BP) polycrystalline layer according to the present invention grown on the light emitting layer. Can be configured on the basis. A polycrystalline layer composed of a single crystal of boron phosphide having a forbidden band width of about 3 eV at room temperature can be used as a clad layer sandwiching the light emitting layer. The light emitting layer is Ga_XIn_1-XN (0 ≦ X ≦ 1) or gallium phosphide nitride (GaN)_1-YP_Y: 0 <Y ≦ 1) or the like, or a single or multiple quantum well structure having a well layer. Incidentally, the barrier layer for the well layer is made of aluminum gallium nitride (Al_XGa_1-XN: 0 ≦ X ≦ 1) and GaN_1-ZP_Z(0 ≦ Z <1, Z <Y) or the like. An n-type ohmic electrode is provided on the n-type boron phosphide polycrystalline layer that forms the surface layer of the laminated structure, and a p-type ohmic electrode is disposed on the back surface of the p-type Si single crystal substrate to form a pn junction. Type heterostructure LEDs can be constructed.
[0022]
Moreover, oxygen (O) grown through an undoped {111} -Si single crystal substrate having a high resistance and a polycrystalline buffer layer containing boron (B) and phosphorus (P) on the substrate is formed. From a laminated structure including an added high-resistance boron phosphide polycrystalline layer and a high-purity n-type gallium nitride (GaN) layer as an active layer (electron transit layer) on the polycrystalline layer, a heterojunction type An electronic device such as a field effect transistor (FET) can be configured. In the FET, a Schottky junction type gate electrode is formed on the active layer, and a source and a source are disposed at opposite positions with the gate electrode on the surface of the n-type contact layer stacked on the active layer interposed therebetween. A drain ohmic electrode is provided and configured.
[0023]
[Action]
The single crystal body including a twin crystal composed of a boron phosphide-based semiconductor crystal according to the present invention has an effect of suppressing upward propagation of misfit dislocations caused by lattice mismatch between a Si single crystal substrate and a boron phosphide-based semiconductor. Have.
[0024]
【Example】
Hereinafter, the present invention will be specifically described using an example in which an LED is manufactured from a laminated structure including a boron phosphide (BP) layer made of a polycrystalline layer on a {111} -Si single crystal substrate.
[0025]
FIG. 4 shows a schematic plan view of the LED 1B according to this example. FIG. 5 shows a schematic cross-sectional view of the LED 1B along the broken line X-X ′ shown in FIG.
[0026]
The laminated structure 1A for the LED 1B application is configured by using, as the substrate 101, a Si single crystal having a surface that is 2 ° off from the p-type (111) surface by boron (B) doping. On the substrate 101, triethylboron ((C₂H_Five)_ThreeB) / phosphine (PH_Three) / Hydrogen (H₂) A buffer layer 102 made of boron phosphide mainly composed of amorphous material was deposited in an as-grown state at 350 ° C. by a system atmospheric pressure MOCVD method. The layer thickness of the buffer layer 102 was about 10 nm.
[0027]
On the surface of the buffer layer 102, a p-type boron phosphide (BP) layer 103 made of a polycrystalline layer was laminated at 1050 ° C. by using the MOCVD vapor phase growth means. The growth rate was set at 40 nm per minute. The carrier concentration of the p-type boron phosphide layer 103 is 1 × 10¹⁹cm^-3The layer thickness was about 400 nm. The band gap of the p-type boron phosphide layer 103 at room temperature was approximately 3.0 eV.
[0028]
The internal crystal structure of the p-type boron phosphide layer 103 was analyzed from the cross-sectional TEM image and electron diffraction pattern using a transmission electron microscope (TEM). FIG. 6 is a copy diagram of a diffraction pattern of the p-type boron phosphide layer 103 obtained by making an electron beam incident parallel to the <110> crystal direction of the Si single crystal substrate 101. As shown in FIG. 6, diffraction spots 19 derived from the {111} crystal plane of each single crystal 103a forming the p-type boron phosphide layer 103 made of a polycrystalline layer are parallel to the <111> crystal direction, It was positioned adjacent to the diffraction spots 20 derived from the (111) crystal plane of the single crystal substrate 101. From this, it was shown that the single crystal body 103a is a crystal body in which {111} crystal planes of boron phosphide are stacked in parallel to the <111> crystal direction of the Si single crystal substrate surface. Further, as shown in the diffraction pattern of FIG. 6, the {111} crystal plane is twinned in the vicinity with the diffraction spot of the single crystal body 103a aligned in the <111> crystal direction of the Si single crystal of the substrate 101 as the center of point symmetry. The diffraction spots 21 from the twinning planes were also confirmed. From this, it was confirmed that the single crystal body 103a contains twins having {111} crystal planes as twin planes. From the position of the diffraction spots 21 due to the twins, it was shown that the twin planes exist in a direction of 60 degrees with respect to the <110> crystal direction of the BP crystal.
[0029]
On the surface of the p-type boron phosphide layer 103, trimethylgallium ((CH_Three)_ThreeGa) / trimethylindium ((CH_Three)_ThreeIn / ammonia (NH_Three) / H₂Of normal hexagonal n-type gallium nitride indium (Ga) at 850 ° C._0.90In_0.10A light emitting layer 104 made of N) was laminated. The layer thickness of the light emitting layer 104 was about 10 nm.
[0030]
On the surface of the light emitting layer 104, an undoped n-type boron phosphide layer 105 made of a polycrystalline layer was laminated. The n-type boron phosphide layer 105 was laminated at 1050 ° C. using the above MOCVD vapor phase growth means. The growth rate was set at 30 nm per minute. Similar to the p-type boron phosphide layer 103, the n-type boron phosphide layer 105 is composed of an assembly of regular tetrahedral single crystals 105a made of (111) crystal planes of BP. It was. The carrier concentration of the n-type boron phosphide layer is 8 × 10¹⁸cm^-3The layer thickness was about 300 nm. The band gap of the n-type boron phosphide layer 105 at room temperature was approximately 3.0 eV.
[0031]
From the electron diffraction pattern, the {111} crystal planes of the single crystal bodies 105a forming the n-type boron phosphide layer 105 were arranged parallel to the <111> crystal direction of the (111) -Si single crystal substrate 101. . In addition, the presence of twins having the {111} crystal plane of the BP crystal as a twin plane was confirmed in the single crystal body 105a. The twin planes existed in the direction of 60 degrees with respect to the <110> crystal direction of the BP crystal.
[0032]
A pn-junction type double hetero (p-type boron phosphide layer 103 and n-type boron phosphide layer 105 having a room temperature forbidden band width of about 3.0 eV and a light emitting layer 104 made of a material having the same lattice spacing are used. The light emitting unit 106 having a (DH) structure was configured.
[0033]
A circular n-type ohmic electrode 107 that also serves as a pedestal electrode is disposed at the center of the surface of the n-type boron phosphide layer 105. The n-type ohmic electrode 107 was constituted by a multilayer structure in which a vacuum deposited film of gold (Au) / germanium (Ge) alloy / nickel (Ni) / gold was stacked. The diameter of the n-type ohmic electrode 107 was about 120 μm. Further, a p-type ohmic electrode 108 is disposed on substantially the entire back surface of the p-type Si single crystal substrate 101 to constitute the LED 1B. The p-type ohmic electrode 108 was composed of an aluminum (Al) vacuum deposition film. The Si single crystal substrate 101 was cut in a direction parallel to and perpendicular to the [211] direction to obtain a square LED 1B having a side of about 300 μm.
[0034]
After connecting a gold (Au) wire to the n-type ohmic electrode 107, an operating current of 20 milliamperes (mA) is passed in the forward direction between the n-type ohmic electrode 107 and the p-type ohmic electrode 108 to investigate the light emission characteristics. did. The emission center wavelength was about 420 nm. The full width at half maximum (FWHM) of the emission spectrum was 32 nm. In the present invention, since the light emitting layer 104 is formed using the p-type boron phosphide layer 103 having a low misfit dislocation density as a base layer, a non-light emitting dark line (dark line) (by Yonezu, Hiroo, "Optical communication element engineering-light emitting / light receiving element" (May 20, 1995, published by Engineering Book Co., Ltd., 5th edition, pages 155 to 156) is not visually recognized, and has a substantially uniform intensity from the entire surface of the light emitting region. As a result, the luminance in a chip state measured using a general integrating sphere is 8 millicandelas (mcd), and an LED with high emission intensity is provided. In addition, in the current-voltage (IV) characteristics of the LED 1B, the occurrence of a local breakdown voltage due to the dislocation is not observed, and the configuration of the present invention is favorable. pn junction characteristics It was shown that a pn junction type light emitting unit 106 exhibiting (rectifying property) is provided, and the forward voltage (so-called Vf) obtained from the IV characteristics is 3.6 V (forward current = 20 mA), Further, the reverse voltage was 6 V (reverse current = 10 μA), and an LED having a high breakdown voltage was provided.
[0035]
【The invention's effect】
In the present invention, a boron phosphide-based semiconductor layer provided on a Si single crystal substrate whose surface has a {111} -crystal plane includes a twin crystal that can absorb misfit dislocations and suppress the propagation of dislocations. Therefore, a boron phosphide-based semiconductor layer having excellent crystallinity with a low dislocation density can be formed. By using this, a boron phosphide-based semiconductor element having excellent characteristics can be formed. For example, there is an effect that it is possible to provide a boron phosphide-based semiconductor light-emitting element that is excellent in emission intensity, rectification property, and pressure resistance.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing the shape of a single crystal constituting a polycrystalline layer according to the present invention.
FIG. 2 is a schematic plan view showing a configuration of a polycrystalline layer according to the present invention.
FIG. 3 is a schematic diagram showing a crystal plane intersecting a {111} crystal plane of a boron phosphide-based semiconductor layer according to the present invention.
FIG. 4 is a schematic plan view of an LED according to an embodiment of the present invention.
5 is a schematic cross-sectional view of an LED along a broken line X-X ′ in FIG. 3;
FIG. 6 is a copy of an electron diffraction pattern of a boron phosphide layer according to an example of the present invention.
[Explanation of symbols]
1A Laminated structure
1B LED
11 Si single crystal substrate
12 Boron phosphide semiconductor polycrystalline layer
13 Single crystal
13a Bottom of single crystal
14 Twin plane
15 Twins
16 Joint surface of single crystal
17 {111} crystal plane of single crystal
18 {hkl} face
19 Diffraction spot of boron phosphide single crystal
Diffraction spot of 20 Si single crystal substrate
21 Twin diffraction spots
101 Si single crystal substrate
102 Buffer layer
103 p-type boron phosphide layer
103a single crystal
104 Light emitting layer
105 n-type boron phosphide layer
105a single crystal
106 Light emitting part
107 n-type ohmic electrode
108 p-type ohmic electrode

Claims (7)

A substrate made of a silicon (Si) single crystal and a boron phosphide semiconductor layer made of a boron phosphide semiconductor crystal having the same crystal plane as the crystal plane constituting the surface of the substrate formed on the substrate. In a semiconductor device including a boron phosphide semiconductor layer , the substrate is made of {111} -Si single crystal having a {111} crystal plane as a surface, and the boron phosphide semiconductor layer is formed from {111} of the substrate. A plurality of triangular pyramidal boron phosphide semiconductors having a bottom surface composed of {111} crystal faces of a boron phosphide semiconductor crystal arranged parallel to the crystal face and surrounded by a plane equivalent to the {111} crystal face The boron phosphide semiconductor crystal is composed of a polycrystalline layer in which crystals are assembled, and further includes a twin plane equivalent to the {111} crystal plane inside, and the twin plane inside each boron phosphide semiconductor crystal is constant. phosphide, characterized in that not crystalline direction Semiconductor device including a containing semiconductor layer. There is a heterogeneous (hetero) junction formed by laminating a III-V group compound semiconductor layer on the boron phosphide semiconductor layer , and a gap between crystal planes of the III-V group compound semiconductor layer at the junction plane 2. The semiconductor element including a boron phosphide semiconductor layer according to claim 1 , wherein a distance between crystal planes of the boron phosphide semiconductor layer coincides . A single crystal of the boron phosphide semiconductor crystal is a monomeric boron phosphide (boron).
3. A semiconductor element comprising a boron phosphide semiconductor layer according to claim 1, wherein the semiconductor element comprises a monophosphide) crystal. The boron phosphide semiconductor layer is grown on a {111} -Si single crystal substrate at a temperature of 950 ° C. or higher and 1100 ° C. or lower by a metal organic pyrolysis vapor deposition method (MOCVD method) at a rate of 20 nm per minute. 4. The method for manufacturing a semiconductor element including a boron phosphide semiconductor layer according to claim 1, wherein the semiconductor element is formed to have a thickness of 60 nm or less. The boron phosphide semiconductor layer is grown on a {111} -Si single crystal substrate at a temperature of 1025 ° C. or more and 1075 ° C. or less by a metal organic pyrolysis vapor deposition method (MOCVD method) at a rate of 30 nm per minute. The method for manufacturing a semiconductor element including a boron phosphide semiconductor layer according to claim 4, wherein the semiconductor element is formed to have a thickness of 40 nm or less. A light emitting diode comprising a semiconductor element comprising the boron phosphide semiconductor layer according to claim 1. In the boron phosphide semiconductor layer made of a boron phosphide semiconductor crystal having the same crystal plane as the crystal plane constituting the surface of the substrate, formed on the surface of the substrate made of silicon (Si) single crystal, The substrate is made of a {111} -Si single crystal whose surface is a {111} crystal plane, and the boron phosphide semiconductor layer is made of a boron phosphide semiconductor crystal {arranged in parallel to the {111} crystal plane of the substrate. A polycrystal layer having a bottom surface composed of a 111} crystal face and surrounded by a plane equivalent to the {111} crystal face, which is a collection of a plurality of triangular pyramidal boron phosphide semiconductor crystals, boron phosphide semiconductor crystal includes a {111} crystal face equivalent to twin planes to the internal, boron phosphide semiconductor layer twin planes within each boron phosphide semiconductor crystal is characterized by non-uniform crystal direction.

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