JP7616598B2 - METHOD FOR MANUFACTURING PHOTONIC CRYSTAL STRUCTURE, ... LIGHT EMITTING DEVICE, AND PROJECTOR - Google Patents

Description

The present invention relates to a method for manufacturing a photonic crystal structure, a photonic crystal structure, a light emitting device, and a projector.

Photonic crystals have been the subject of vigorous research worldwide, and in recent years photonic crystal lasers have come into practical use.

For example, Patent Document 1 describes a method of forming a two-dimensional periodic hole structure by lithography and dry etching processing, and then laminating an alternating layer structure of Si/ _SiO2 on this two-dimensional periodic structure by an autocloning mode to fabricate a three-dimensional periodic structure.

JP 2001-249235 A

Photonic crystal structures having three-dimensional periodic structures such as those described above are required to have good periodicity.

One aspect of the method for producing a photonic crystal structure according to the present invention comprises the steps of:
forming a plurality of first columnar sections and a plurality of second columnar sections each having a height smaller than that of the first columnar sections;
growing a first columnar crystal on each of the plurality of first columnar portions and growing a second columnar crystal on each of the plurality of second columnar portions;
having
In the step of growing the first columnar crystals and the second columnar crystals,
a first low refractive index layer and a first high refractive index layer having a refractive index higher than that of the first low refractive index layer are alternately laminated to grow the first columnar crystals;
a second low refractive index layer and a second high refractive index layer having a refractive index higher than that of the second low refractive index layer are alternately laminated to grow the second columnar crystals;
The first low refractive index layer and the second high refractive index layer are disposed at a first position in a stacking direction of the first low refractive index layer and the first high refractive index layer,
The second low refractive index layer and the first high refractive index layer are disposed at a second position different from the first position in the stacking direction.

One aspect of the photonic crystal structure according to the present invention is
A plurality of first columnar portions;
A plurality of second columnar portions each having a height smaller than that of the first columnar portions;
a first columnar crystal provided in each of the plurality of first columnar portions;
second columnar crystals provided in each of the plurality of second columnar portions;
having
The first columnar crystals are
A first low refractive index layer;
a first high refractive index layer having a refractive index higher than that of the first low refractive index layer;
having
the first low refractive index layers and the first high refractive index layers are alternately stacked,
The second columnar crystals are
A second low refractive index layer;
a second high refractive index layer having a refractive index higher than that of the second low refractive index layer;
having
the second low refractive index layer and the second high refractive index layer are alternately stacked,
the first low-refractive index layer and the second high-refractive index layer are provided at a first position in a stacking direction of the first low-refractive index layer and the first high-refractive index layer,
The second low refractive index layer and the first high refractive index layer are provided at a second position different from the first position in the stacking direction.

One aspect of the light emitting device according to the present invention is
One embodiment of the photonic crystal structure;
a light emitting layer provided on the first columnar crystal;
has.

One aspect of the projector according to the present invention is
The present invention has one aspect of the light emitting device.

1 is a cross-sectional view illustrating a photonic crystal structure according to a first embodiment. FIG. 1 is a plan view illustrating a photonic crystal structure according to a first embodiment. 1 is a cross-sectional view illustrating a photonic crystal structure according to a first embodiment. 3 is a flowchart for explaining a method for manufacturing a photonic crystal structure according to the first embodiment. 3A to 3C are cross-sectional views each showing a schematic diagram of a manufacturing process of the photonic crystal structure according to the first embodiment. 3A to 3C are cross-sectional views each showing a schematic diagram of a manufacturing process of the photonic crystal structure according to the first embodiment. TEM image of multiple pillars. TEM image of multiple pillars. FIG. 11 is a cross-sectional view illustrating a photonic crystal structure according to a modified example of the first embodiment. FIG. 11 is a plan view diagrammatically showing a photonic crystal structure according to a modified example of the first embodiment. FIG. 11 is a cross-sectional view illustrating a light emitting device according to a second embodiment. FIG. 11 is a plan view illustrating a light emitting device according to a second embodiment. FIG. 11 is a cross-sectional view illustrating a light emitting device according to a modified example of the second embodiment. FIG. 1 is a diagram illustrating a projector according to an embodiment of the present invention.

Below, preferred embodiments of the present invention will be described in detail with reference to the drawings. Note that the embodiments described below do not unduly limit the content of the present invention described in the claims. Furthermore, not all of the configurations described below are necessarily essential components of the present invention.

1. First embodiment 1.1. Photonic crystal structure First, the photonic crystal structure according to the first embodiment will be described with reference to the drawings. Fig. 1 is a cross-sectional view that shows a model of the photonic crystal structure 100 according to the first embodiment. Fig. 2 is a plan view that shows a model of the photonic crystal structure 100 according to the first embodiment. Fig. 1 is a cross-sectional view taken along line II in Fig. 2.

As shown in Figures 1 and 2, the photonic crystal structure 100 has a substrate 10, a first columnar section 20, a second columnar section 22, a first columnar crystal 30, and a second columnar crystal 40. For convenience, components other than the columnar sections 20 and 22 are not shown in Figure 2.

The substrate 10 has, for example, a support substrate 12 and a buffer layer 14. The support substrate 12 is, for example, a Si substrate, a GaN substrate, a sapphire substrate, a SiC substrate, etc. The buffer layer 14 is provided on the support substrate 12. The buffer layer 14 is, for example, a GaN layer.

In this specification, in the stacking direction (hereinafter also simply referred to as the "stacking direction") of the first low refractive index layer 32 and the first high refractive index layer 34 of the first columnar crystal 30, when the first columnar section 20 is used as a reference, the direction from the first columnar section 20 toward the first columnar crystal 30 is described as "up" and the direction from the first columnar section 20 toward the substrate 10 is described as "down". The direction perpendicular to the stacking direction is also referred to as the "in-plane direction".

A mask layer 16 for forming the columnar sections 20 and 22 is provided on the buffer layer 14. The mask layer 16 is, for example, a titanium layer, a titanium oxide layer, a silicon layer, a silicon oxide layer, or the like.

The first columnar section 20 and the second columnar section 22 are provided on the buffer layer 14. The first columnar section 20 is provided between the substrate 10 and the first columnar crystal 30. The second columnar section 22 is provided between the substrate 10 and the second columnar crystal 40. The columnar sections 20 and 22 have a columnar shape that protrudes upward from the buffer layer 14. The columnar sections 20 and 22 are, for example, GaN layers.

The diameters of the first columnar section 20 and the second columnar section 22 are, for example, 50 nm or more and 500 nm or less. The diameter D1 of the first columnar section 20 is larger than the diameter D2 of the second columnar section 22.

The "diameter of the columnar portion" refers to the diameter when the planar shape of the columnar portions 20, 22 is a circle, and refers to the diameter of the smallest inclusive circle when the planar shape of the columnar portions 20, 22 is not a circle. For example, when the planar shape of the columnar portions 20, 22 is a polygon, the diameter of the smallest circle that contains the polygon, and when the planar shape of the columnar portions 20, 22 is an ellipse, the diameter of the smallest circle that contains the ellipse. The same applies to the "diameter of the columnar crystal" described below.

The height H2 of the second columnar section 22 is smaller than the height H1 of the first columnar section 20. That is, the size of the second columnar section 22 in the stacking direction is smaller than the size of the first columnar section 20 in the stacking direction. In the illustrated example, the difference between the height H1 and the height H2 is equal to the thickness of the second low refractive index layer 42.

A plurality of first columnar sections 20 are provided. A plurality of second columnar sections 22 are provided. The plurality of columnar sections 20, 22 are arranged at a predetermined pitch in a predetermined direction when viewed from the stacking direction. In the example shown in FIG. 2, the plurality of columnar sections 20, 22 are arranged in a triangular lattice pattern. The planar shape of the columnar sections 20, 22 is a regular hexagon.

The "pitch of the columnar parts" refers to the distance between the centers of adjacent columnar parts 20, 22 along a specified direction. The "center of the columnar part" refers to the center of the circle when the planar shape of the columnar parts 20, 22 is a circle, and refers to the center of the smallest inclusive circle when the planar shape of the columnar parts 20, 22 is a shape other than a circle. For example, when the planar shape of the columnar parts 20, 22 is a polygon, the center of the smallest circle that contains the polygon inside, and when the planar shape of the columnar parts 20, 22 is an ellipse, the center of the smallest circle that contains the ellipse inside.

The first columnar crystal 30 is provided on each of the multiple first columnar sections 20. The first columnar crystal 30 has a first low-refractive index layer 32 and a first high-refractive index layer 34 having a higher refractive index than the first low-refractive index layer 32. A plurality of first low-refractive index layers 32 are provided. A plurality of first high-refractive index layers 34 are provided. The first low-refractive index layers 32 and the first high-refractive index layers 34 are alternately stacked. The first low-refractive index layers 32 and the first high-refractive index layers 34 are arranged in the stacking direction at a predetermined period. The first low-refractive index layers 32 are, for example, AlGaN layers. The first high-refractive index layers 34 are, for example, GaN layers.

The second columnar crystal 40 is provided on each of the multiple second columnar sections 22. The second columnar crystal 40 has a second low-refractive index layer 42 and a second high-refractive index layer 44 having a higher refractive index than the second low-refractive index layer 42. A plurality of second low-refractive index layers 42 are provided. A plurality of second high-refractive index layers 44 are provided. The second low-refractive index layers 42 and the second high-refractive index layers 44 are alternately stacked. The second low-refractive index layers 42 and the second high-refractive index layers 44 are arranged in the stacking direction, for example, with the same period as the first low-refractive index layer 32 and the first high-refractive index layer 34, and shifted by half a period with respect to the first low-refractive index layer 32 and the first high-refractive index layer 34. The number of second low-refractive index layers 42 is the same as the number of first low-refractive index layers 32. The number of second high-refractive index layers 44 is the same as the number of first high-refractive index layers 34. The second low-refractive index layer 42 is, for example, an AlGaN layer. The second high refractive index layer 44 is, for example, a GaN layer.

At a first position P1 in the stacking direction, a first low refractive index layer 32 and a second high refractive index layer 44 are provided. The first low refractive index layer 32 and the second high refractive index layer 44 are arranged in the in-plane direction at a predetermined period at the first position P1. In the illustrated example, the first position P1 is a position that passes through the center of the second high refractive index layer 44 located at the top. The second high refractive index layer 44 is provided on the side of the first low refractive index layer 32.

At the second position P2 in the stacking direction, the second low refractive index layer 42 and the first high refractive index layer 34 are provided. At the second position P2, the second low refractive index layer 42 and the first high refractive index layer 34 are arranged in the in-plane direction with the same period as the period of the first low refractive index layer 32 and the second high refractive index layer 44 at the first position P1. The second position P2 is a position different from the first position P1. In the illustrated example, the second position P2 is a position that passes through the center of the second low refractive index layer 42 located at the top.

Here, FIG. 3 is a diagram for explaining the shapes of the first columnar crystal 30 and the second columnar crystal 40 in more detail.

In FIG. 1, for convenience, the diameter of the second columnar crystal 40 is illustrated as being constant, but the second columnar crystal 40 has a tapered portion 40a whose diameter gradually increases upward, and a constant diameter portion 40b whose diameter is constant, as shown in FIG. 3. The tapered portion 40a is provided on the second columnar portion 22. The constant diameter portion 40b is provided on the tapered portion 40a. In the illustrated example, the diameter of the first columnar crystal 30 is constant. The maximum diameter D3 of the first columnar crystal 30 and the maximum diameter D4 of the second columnar crystal 40 are equal to each other. The columnar crystals 30 and 40 have maximum diameters D3 and D4, respectively, at the first position P1. Furthermore, the columnar crystals 30 and 40 have maximum diameters D3 and D4, respectively, at the second position P2.

In FIG. 1, for convenience, the number of pairs between the first low refractive index layer 32 and the first high refractive index layer 34, and the number of pairs between the second low refractive index layer 42 and the second high refractive index layer 44 are illustrated as three pairs, but the number of pairs between the first low refractive index layer 32 and the first high refractive index layer 34, and the number of pairs between the second low refractive index layer 42 and the second high refractive index layer 44 are more than three pairs, for example, 20 pairs or more.

In the photonic crystal structure 100, the effect of the photonic crystal can be expressed in the stacking direction due to the refractive index difference between the first low-refractive index layer 32 and the first high-refractive index layer 34, and the refractive index difference between the second low-refractive index layer 42 and the second high-refractive index layer 44. Furthermore, the effect of the photonic crystal can be expressed in the in-plane direction due to the refractive index difference between the first low-refractive index layer 32 and the second high-refractive index layer 44, and the refractive index difference between the second low-refractive index layer 42 and the first high-refractive index layer 34. Therefore, the photonic crystal structure 100 has the properties of a three-dimensional photonic crystal.

The photonic crystal structure 100 has, for example, the following effects:

The photonic crystal structure 100 has a plurality of first columnar sections 20, a plurality of second columnar sections 22 each having a height smaller than that of the first columnar sections 20, a first columnar crystal 30 provided on each of the plurality of first columnar sections 20, and a second columnar crystal 40 provided on each of the plurality of second columnar sections 22. The first columnar crystal 30 has a first low-refractive index layer 32 and a first high-refractive index layer 34 having a higher refractive index than the first low-refractive index layer 32, and the first low-refractive index layer 32 and the first high-refractive index layer 34 are alternately stacked. The second columnar crystal 40 has a second low-refractive index layer 42 and a second high-refractive index layer 44 having a higher refractive index than the second low-refractive index layer 42, and the second low-refractive index layer 42 and the second high-refractive index layer 44 are alternately stacked. A first low-refractive index layer 32 and a second high-refractive index layer 44 are provided at a first position P1 in the stacking direction, and a second low-refractive index layer 42 and a first high-refractive index layer 34 are provided at a second position P2 different from the first position P1 in the stacking direction. Therefore, the photonic crystal structure 100 can have a three-dimensional periodic structure with good periodicity.

For example, if an uneven surface is formed on a substrate, and layers with different refractive indices are formed on the substrate with the uneven surface, the steps will change as the layers are stacked, making it impossible to maintain good periodicity. In the photonic crystal structure 100, columnar sections 20 and 22 of different heights are provided, and columnar crystals 30 and 40 are provided on top of these, respectively, so that good periodicity can be achieved.

In the photonic crystal structure 100, the maximum diameter D3 of the first columnar crystal 30 and the maximum diameter D4 of the second columnar crystal 40 are equal to each other. Therefore, in the photonic crystal structure 100, the growth rates of the columnar crystals 30, 40 in the portions where the maximum diameters D3, D4 are the same can be made the same. This allows the columnar crystals 30, 40 to grow while maintaining the height difference between the first columnar crystal 30 and the second columnar crystal 40 in the portions where the maximum diameters D3, D4 are the same. As a result, it becomes easier to control the periodic structure in the in-plane direction.

In the photonic crystal structure 100, the diameter D1 of the first columnar section 20 is larger than the diameter D2 of the second columnar section 22. When the columnar section is grown as a crystal, the larger the diameter of the columnar section, the faster the growth rate in the stacking direction. Therefore, in the photonic crystal structure 100, the height of the first columnar section 20 can be made larger than the height of the second columnar section 22.

1.2. Manufacturing Method of Photonic Crystal Structure Next, a manufacturing method of the photonic crystal structure 100 according to the first embodiment will be described with reference to the drawings. Fig. 4 is a flow chart for explaining the manufacturing method of the photonic crystal structure 100 according to the first embodiment. Fig. 5 and Fig. 6 are cross-sectional views that typically show the manufacturing process of the photonic crystal structure 100 according to the first embodiment.

5, the buffer layer 14 is grown on the support substrate 12 (step S1). The buffer layer 14 is grown by crystal growth, for example, by MOCVD (Metal Organic Chemical Vapor Deposition).
The epitaxial growth is performed by using a method such as a Radio Frequency Vapor Deposition (RF-MBE) method and a Radio Frequency Molecular Beam Epitaxy (RF-MBE) method. In step S1, a substrate 10 can be formed.

Next, a mask layer 16 is formed on the buffer layer 14 (step S2). The mask layer 16 is formed by, for example, sputtering, CVD (Chemical Vapor Deposition), or electron beam deposition, and is patterned by photolithography and etching techniques.

As shown in FIG. 6, a plurality of first columnar sections 20 and a plurality of second columnar sections 22 are formed on the buffer layer 14 using the mask layer 16 as a mask (step S3). Specifically, the columnar sections 20 and 22 are grown by crystal growth. The crystal growth of the columnar sections 20 and 22 is, for example, epitaxial growth using the MOCVD method or the RF-MBE method. Since the growth rate of the columnar sections 20 and 22 in the stacking direction changes by changing the diameters D1 and D2 of the columnar sections 20 and 22, the heights H1 and H2 of the columnar sections 20 and 22 can be controlled by the diameter of the openings provided in the mask layer 16. Specifically, since the diameter D1 of the first columnar section 20 is larger than the diameter D2 of the second columnar section 22, the height HD1 of the first columnar section 20 is larger than the height H2 of the second columnar section 22.

Here, Fig. 7 and Fig. 8 are SEM (Scanning Electron Microscope) images of multiple columnar portions. Fig. 7 is a plan view, and Fig. 8 is a perspective view. As shown in Figs. 7 and 8, it can be seen that the height of the columnar portion increases when the diameter of the columnar portion is large.

As shown in FIG. 1, the first columnar crystal 30 is grown on each of the first columnar sections 20, and the second columnar crystal 40 is grown on each of the second columnar sections 22 (step S4). In step S4, the first low-refractive index layer 32 and the first high-refractive index layer 34 are alternately stacked to grow the first columnar crystal 30. Furthermore, the second low-refractive index layer 42 and the second high-refractive index layer 44 are alternately stacked to grow the second columnar crystal 40. The crystal growth of the first low-refractive index layer 32 and the crystal growth of the second low-refractive index layer 42 are performed in the same process. The crystal growth of the first high-refractive index layer 34 and the crystal growth of the second high-refractive index layer 44 are performed in the same process. The crystal growth of the low-refractive index layers 32, 42 and the high-refractive index layers 34, 44 is epitaxial growth using, for example, the MOCVD method or the RF-MBE method.

In step S4, the columnar crystals 30, 40 are grown under conditions in which the second columnar crystals 40 expand in the in-plane direction and the smaller diameter second columnar crystals 40 expand due to the shadow effect, as shown in FIG. 3, so that the diameters D3, D4 become equal. This allows the growth rates of the columnar crystals 30, 40 at the portions where the maximum diameters D3, D4 are the same to be the same. As a result, in the portions where the maximum diameters D3, D4 are the same, the columnar crystals 30, 40 can be grown while maintaining the difference in height between the first columnar crystal 30 and the second columnar crystal 40. The "shadow effect" refers to the phenomenon in which the raw material becomes more difficult to enter when the gap between the columnar portions 20, 22 becomes narrow.

In step S4, the first low refractive index layer 32 and the second high refractive index layer 44 are disposed at a first position P1 in the stacking direction. Furthermore, the second low refractive index layer 42 and the first high refractive index layer 34 are disposed at a second position P2 in the stacking direction.

The above steps allow the production of the photonic crystal structure 100.

1.3. Modifications of the Photonic Crystal Structure Next, a photonic crystal structure according to a modification of the first embodiment will be described with reference to the drawings. Fig. 9 is a cross-sectional view that shows a model of a photonic crystal structure 110 according to a modification of the first embodiment. Fig. 10 is a plan view that shows a model of a photonic crystal structure 110 according to a modification of the first embodiment. Fig. 9 is a cross-sectional view taken along line IX-IX in Fig. 10. For convenience, Fig. 10 omits illustration of members other than the columnar portions 20, 22.

In the following description of the photonic crystal structure 110 according to a modified example of the first embodiment, components having the same functions as the components of the photonic crystal structure 100 according to the first embodiment described above are given the same reference numerals, and detailed descriptions thereof will be omitted.

As shown in Figures 1 and 2, the planar shape of the multiple columnar portions 20, 22 of the photonic crystal structure 100 described above is arranged in a triangular lattice pattern. Furthermore, the planar shape of the columnar portions 20, 22 is a regular hexagon.

In contrast, as shown in Figures 9 and 10, the photonic crystal structure 110 has multiple columnar sections 20, 22 arranged in a square lattice shape in plan view. The columnar sections 20, 22 have a circular plan view.

2. Second embodiment 2.1. Light-emitting device Next, a light-emitting device according to a second embodiment will be described with reference to the drawings. Fig. 11 is a cross-sectional view that shows a light-emitting device 200 according to the second embodiment. Fig. 12 is a plan view that shows a light-emitting device 200 according to the second embodiment. Fig. 11 is a cross-sectional view taken along line XI-XI in Fig. 12. For convenience, Fig. 12 omits illustration of members other than the columnar portions 20 and 22.

As shown in Figs. 11 and 12, the light emitting device 200 has, for example, the above-mentioned photonic crystal structure 100. Furthermore, the light emitting device 200 has a first light emitting layer 50, a second light emitting layer 52, a third columnar crystal 60, and a fourth columnar crystal 70.

The first light-emitting layer 50 is provided on the first columnar crystal 30. The first light-emitting layer 50 is provided between the first columnar crystal 30 and the third columnar crystal 60. The second light-emitting layer 52 is provided on the second columnar crystal 40. The second light-emitting layer 52 is provided between the second columnar crystal 40 and the fourth columnar crystal 70. In the illustrated example, the first light-emitting layer 50 is in contact with the first high-refractive index layer 34 and the third high-refractive index layer 64. The second light-emitting layer 52 is in contact with the second high-refractive index layer 44 and the fourth high-refractive index layer 74.

The first light-emitting layer 50 and the second light-emitting layer 52 generate light when light is incident thereon. The light-emitting layers 50 and 52 have, for example, a well layer made of an i-type InGaN layer and a barrier layer made of an i-type GaN layer. The light-emitting layers 50 and 52 have, for example, an MQW (Multiple Quantum Well) structure made up of a well layer and a barrier layer. The number of well layers and the number of barrier layers are not particularly limited. The light-emitting layers 50 and 52 may have an SQW (Single Quantum Well) structure.

The third columnar crystals 60 are provided on the first light-emitting layer 50. The third columnar crystals 60 are
The optical waveguide has a low refractive index layer 62 and a third high refractive index layer 64 having a refractive index higher than that of the third low refractive index layer 62. A plurality of third low refractive index layers 62 are provided. A plurality of third high refractive index layers 64 are provided. The third low refractive index layers 62 and the third high refractive index layers 64 are alternately stacked. The third low refractive index layers 62 and the third high refractive index layers 64 are arranged in the stacking direction at a predetermined period. The third low refractive index layers 62 are, for example, AlGaN layers. The third high refractive index layers 64 are, for example, GaN layers.

The fourth columnar crystal 70 is provided on the second light-emitting layer 52. The fourth columnar crystal 70 has a fourth low-refractive index layer 72 and a fourth high-refractive index layer 74 having a higher refractive index than the fourth low-refractive index layer 72. A plurality of fourth low-refractive index layers 72 are provided. A plurality of fourth high-refractive index layers 74 are provided. The fourth low-refractive index layers 72 and the fourth high-refractive index layers 74 are alternately stacked. The fourth low-refractive index layers 72 and the fourth high-refractive index layers 74 are arranged in the stacking direction, for example, with the same period as the third low-refractive index layers 62 and the third high-refractive index layers 64, and shifted by half a period with respect to the third low-refractive index layers 62 and the third high-refractive index layers 64. The number of the fourth low-refractive index layers 72 is the same as the number of the third low-refractive index layers 62. The number of the fourth high-refractive index layers 74 is the same as the number of the third high-refractive index layers 64. The fourth low-refractive index layers 72 are, for example, AlGaN layers. The fourth high refractive index layer 74 is, for example, a GaN layer.

In the light emitting device 200, defects that disrupt the periodicity of the periodic structure are intentionally provided, so that light can be strongly localized in the defects. Specifically, a first columnar section 20 is provided at position A on the substrate 10. This disrupts the periodicity of the columnar sections 20 and 22, and light can be localized in the first light emitting layer 50 provided on the first columnar section 20 located at position A. In the region excluding position A, the first low refractive index layer 32 and the second high refractive index layer 44, the second low refractive index layer 42 and the first high refractive index layer 34, the third low refractive index layer 62 and the fourth high refractive index layer 74, and the fourth low refractive index layer 72 and the third high refractive index layer 64 are periodically arranged in the in-plane direction.

In the light-emitting device 200, the incident excitation light is absorbed by the light-emitting layers 50 and 52, and electrons are excited to emit light. The generated light is localized at position A due to the effect of the photonic crystal in the in-plane direction and stacking direction, and receives gain in the first light-emitting layer 50 to produce laser oscillation. The light-emitting device 200 then emits laser light in the stacking direction.

In the light emitting device 200, spontaneous emission is suppressed due to the effect of the photonic crystal in the in-plane direction and the stacking direction, allowing carriers to be efficiently accumulated. This makes it possible to realize a semiconductor laser with a low threshold.

Although not shown, a reflective layer may be provided between the support substrate 12 and the buffer layer 14 or below the support substrate 12. The reflective layer is, for example, a DBR (Distributed Bragg Reflector) layer. The reflective layer can reflect the light generated in the first light-emitting layer 50, and the light-emitting device 200 can emit light only from the side opposite to the substrate 10.

2.2. Method for Manufacturing the Light-Emitting Device Next, a method for manufacturing the light-emitting device 200 according to the second embodiment will be described with reference to the drawings.

Up to the point where the first columnar crystal 30 and the second columnar crystal 40 are grown, the manufacturing method is the same as that of the photonic crystal structure 100 described above.

11 , the first light-emitting layer 50 is grown on the first columnar crystals 30, and the second light-emitting layer 52 is grown on the second columnar crystals 40. The light-emitting layers 50 and 52 are grown by epitaxial growth using, for example, the MOCVD method or the RF-MBE method. The crystal growth of the first light-emitting layer 50 and the crystal growth of the second light-emitting layer 52 are performed in the same process.

Next, the third columnar crystals 60 are grown on the first light-emitting layer 50, and the fourth columnar crystals 70 are grown on the second light-emitting layer 52. The crystal growth of the columnar crystals 60, 70 is epitaxial growth using, for example, the MOCVD method or the RF-MBE method. The crystal growth of the third columnar crystals 60 and the crystal growth of the fourth columnar crystals 70 are performed in the same process.

The above steps allow the light emitting device 200 to be manufactured.

2.3 Modifications of the Light Emitting Device Next, a light emitting device according to a modification of the second embodiment will be described with reference to the drawings. Fig. 13 is a cross-sectional view showing a light emitting device 210 according to a modification of the second embodiment.

In the following description of the light-emitting device 210 according to a modified example of the second embodiment, components having the same functions as the components of the light-emitting device 200 according to the second embodiment described above are given the same reference numerals, and detailed descriptions thereof will be omitted.

As shown in FIG. 11, the light-emitting device 200 described above emits light when light is incident on the first light-emitting layer 50.

In contrast, the light emitting device 210 emits light when a current is injected into the first light emitting layer 50, as shown in FIG. 13.

In the light emitting device 210, the buffer layer 14, the columnar sections 20 and 22, and the high refractive index layers 34 and 44 are, for example, n-type GaN layers doped with Si. The low refractive index layers 32 and 42 are n-type AlGaN layers doped with Si. The high refractive index layers 64 and 74 are p-type GaN layers doped with Mg. The low refractive index layers 62 and 72 are p-type AlGaN layers doped with Mg.

The light emitting device 210 has a first electrode 80 and a second electrode 82.

The first electrode 80 is provided on the buffer layer 14. The buffer layer 14 may be in ohmic contact with the first electrode 80. The first electrode 80 is electrically connected to the columnar crystals 30, 40. In the illustrated example, the first electrode 80 is electrically connected to the columnar crystals 30, 40 via the buffer layer 14 and the columnar portions 20, 22. The first electrode 80 is one electrode for injecting a current into the first light-emitting layer 50. As the first electrode 80, for example, a layer formed by laminating a Cr layer, a Ni layer, and an Au layer in this order from the buffer layer 14 side is used.

The second electrode 82 is provided on the columnar crystals 60, 70. The second electrode 82 is electrically connected to the columnar crystals 60, 70. The columnar crystals 60, 70 may be in ohmic contact with the second electrode 82. The second electrode 82 is the other electrode for injecting a current into the first light-emitting layer 50. For example, ITO (indium tin oxide) is used as the second electrode 82. The electrodes 80, 82 are formed by, for example, a vacuum deposition method.

In the light emitting device 210, a pin diode is formed by the p-type columnar crystals 60, 70, the i-type first light emitting layer 50 not doped with impurities, and the n-type columnar crystals 30, 40. In the light emitting device 210, when a forward bias voltage of the pin diode is applied between the first electrode 80 and the second electrode 82, a current is injected into the first light emitting layer 50, and recombination of electrons and holes occurs in the first light emitting layer 50. This recombination causes light emission. The light generated in the first light emitting layer 50 is localized at position A due to the effect of the photonic crystal in the in-plane direction and the stacking direction, and receives gain in the first light emitting layer 50 to oscillate as a laser. Then, the light emitting device 210 emits laser light in the stacking direction.

The density of the current injected into the second light-emitting layer 52 may be smaller than the density of the current injected into the first light-emitting layer 50. Since the diameter of the second columnar section 22 is smaller than the diameter of the first columnar section 20, the resistance of the second columnar section 22 is high. This allows the density of the current injected into the second light-emitting layer 52 to be reduced. As described above, the light is localized in the first light-emitting layer 50 provided on the first columnar section 20 located at position A, so that the first light-emitting layer 50 can be made to emit light efficiently by selectively injecting a current into the first light-emitting layer 50.

In the above, the light emitting devices 200 and 210 are described as semiconductor lasers, but the light emitting devices 200 and 210 may be LEDs (Light Emitting Diodes).

3. Third Embodiment Next, a projector according to a third embodiment will be described with reference to the drawings. Fig. 14 is a diagram that illustrates a projector 900 according to this embodiment.

The projector 900 has, for example, a light-emitting device 210 as a light source.

Projector 900 has a housing (not shown) and red light source 210R, green light source 210G, and blue light source 210B that are provided in the housing and emit red light, green light, and blue light, respectively. For convenience, red light source 210R, green light source 210G, and blue light source 210B are simplified in FIG. 14.

The projector 900 further includes a first optical element 902R, a second optical element 902G, a third optical element 902B, a first light modulation device 904R, a second light modulation device 904G, a third light modulation device 904B, and a projection device 908, which are provided within the housing. The first light modulation device 904R, the second light modulation device 904G, and the third light modulation device 904B are, for example, transmissive liquid crystal light valves. The projection device 908 is, for example, a projection lens.

Light emitted from the red light source 210R is incident on the first optical element 902R. The light emitted from the red light source 210R is collected by the first optical element 902R. The first optical element 902R may have a function other than collecting light. The same applies to the second optical element 902G and the third optical element 902B described below.

The light collected by the first optical element 902R is incident on the first light modulation device 904R. The first light modulation device 904R modulates the incident light according to image information. The projection device 908 then enlarges the image formed by the first light modulation device 904R and projects it onto the screen 910.

The light emitted from the green light source 210G is incident on the second optical element 902G. The light emitted from the green light source 210G is collected by the second optical element 902G.

The light collected by the second optical element 902G is incident on the second light modulation device 904G. The second light modulation device 904G modulates the incident light according to image information. The projection device 908 then enlarges the image formed by the second light modulation device 904G and projects it onto the screen 910.

The light emitted from the blue light source 210B is incident on the third optical element 902B. The light emitted from the blue light source 210B is collected by the third optical element 902B.

The light collected by the third optical element 902B enters the third light modulation device 904B. The third light modulation device 904B modulates the incident light according to image information. The projection device 908 then enlarges the image formed by the third light modulation device 904B and projects it onto the screen 910.

The projector 900 may also have a cross dichroic prism 906 that combines the light emitted from the first light modulation device 904R, the second light modulation device 904G, and the third light modulation device 904B and directs the light to the projection device 908.

The three color lights modulated by the first light modulation device 904R, the second light modulation device 904G, and the third light modulation device 904B enter the cross dichroic prism 906. The cross dichroic prism 906 is formed by bonding together four right-angle prisms, and a dielectric multilayer film that reflects red light and a dielectric multilayer film that reflects blue light are arranged on its inner surface. These dielectric multilayer films combine the three color lights to form light that represents a color image. The combined light is then projected by the projection device 908 onto the screen 910, and an enlarged image is displayed.

The red light source 210R, the green light source 210G, and the blue light source 210B may directly form an image without using the first light modulation device 904R, the second light modulation device 904G, and the third light modulation device 904B, by controlling the light emitting device 210 as a pixel of the image according to image information. The projection device 908 may then enlarge and project the image formed by the red light source 210R, the green light source 210G, and the blue light source 210B onto the screen 910.

In the above example, a transmissive liquid crystal light valve was used as the light modulation device, but a light valve other than liquid crystal may be used, or a reflective light valve may be used. Examples of such light valves include a reflective liquid crystal light valve and a digital micro mirror device. The configuration of the projection device may be changed as appropriate depending on the type of light valve used.

The light source can also be applied to a light source device of a scanning type image display device having a scanning means, which is an image forming device that displays an image of a desired size on a display surface by scanning light from the light source on a screen.

The light-emitting device according to the above-described embodiment can be used for purposes other than projectors. Examples of uses other than projectors include indoor and outdoor lighting, display backlights, laser printers, scanners, car lights, sensing devices that use light, and light sources for communication devices. The light-emitting device according to the above-described embodiment can also be used as a light-emitting element in an LED display that displays images by arranging tiny light-emitting elements in an array.

The above-described embodiment and modified examples are merely examples, and the present invention is not limited to these. For example, each embodiment and each modified example can be appropriately combined.

The present invention includes configurations that are substantially the same as the configurations described in the embodiments, for example, configurations with the same functions, methods, and results, or configurations with the same purpose and effects. The present invention also includes configurations in which non-essential parts of the configurations described in the embodiments are replaced. The present invention also includes configurations that achieve the same effects as the configurations described in the embodiments, or configurations that can achieve the same purpose. The present invention also includes configurations in which publicly known technology is added to the configurations described in the embodiments.

The following can be derived from the above-described embodiment and variant examples:

One aspect of the method for producing a photonic crystal structure includes the steps of:
forming a plurality of first columnar sections and a plurality of second columnar sections each having a height smaller than that of the first columnar sections;
growing a first columnar crystal on each of the plurality of first columnar portions and growing a second columnar crystal on each of the plurality of second columnar portions;
having
In the step of growing the first columnar crystals and the second columnar crystals,
a first low refractive index layer and a first high refractive index layer having a refractive index higher than that of the first low refractive index layer are alternately laminated to grow the first columnar crystals;
a second low refractive index layer and a second high refractive index layer having a refractive index higher than that of the second low refractive index layer are alternately laminated to grow the second columnar crystals;
The first low refractive index layer and the second high refractive index layer are disposed at a first position in a stacking direction of the first low refractive index layer and the first high refractive index layer,
The second low refractive index layer and the first high refractive index layer are disposed at a second position different from the first position in the stacking direction.

This method for manufacturing a photonic crystal structure makes it possible to manufacture a photonic crystal structure having a three-dimensional periodic structure with good periodicity.

In one embodiment of a method for producing a photonic crystal structure,
The maximum diameter of the first columnar crystals and the maximum diameter of the second columnar crystals may be equal to each other.

This method for manufacturing a photonic crystal structure allows the growth rates of the first columnar crystal and the second columnar crystal to be the same.

In one embodiment of a method for producing a photonic crystal structure,
In the step of forming the first columnar section and the second columnar section, the first columnar section and the second columnar section may be formed by crystal growth.

In one embodiment of a method for producing a photonic crystal structure,
The first columnar section may have a larger diameter than the second columnar section.

This method for manufacturing a photonic crystal structure allows the height of the first columnar section to be greater than the height of the second columnar section.

One aspect of the photonic crystal structure is
A plurality of first columnar portions;
A plurality of second columnar portions each having a height smaller than that of the first columnar portions;
a first columnar crystal provided in each of the plurality of first columnar portions;
second columnar crystals provided in each of the plurality of second columnar portions;
having
The first columnar crystals are
A first low refractive index layer;
a first high refractive index layer having a refractive index higher than that of the first low refractive index layer;
having
the first low refractive index layers and the first high refractive index layers are alternately stacked,
The second columnar crystals are
A second low refractive index layer;
a second high refractive index layer having a refractive index higher than that of the second low refractive index layer;
having
the second low refractive index layer and the second high refractive index layer are alternately stacked,
the first low-refractive index layer and the second high-refractive index layer are provided at a first position in a stacking direction of the first low-refractive index layer and the first high-refractive index layer,
The second low refractive index layer and the first high refractive index layer are provided at a second position different from the first position in the stacking direction.

This photonic crystal structure can have a three-dimensional periodic structure with good periodicity.

In one embodiment of the photonic crystal structure,
The maximum diameter of the first columnar crystals and the maximum diameter of the second columnar crystals may be equal to each other.

This photonic crystal structure allows the growth rates of the first columnar crystal and the second columnar crystal to be the same.

In one embodiment of the photonic crystal structure,
The first columnar section may have a larger diameter than the second columnar section.

With this photonic crystal structure, the height of the first columnar portion can be made greater than the height of the second columnar portion.

In one embodiment of the light emitting device,
The photonic crystal structure;
a light emitting layer provided on the first columnar crystal;
has.

One aspect of the projector according to the present invention is
The present invention has one aspect of the light emitting device.

10...substrate, 12...support substrate, 14...buffer layer, 16...mask layer, 20...first columnar portion, 22...second columnar portion, 30...first columnar crystal, 32...first low refractive index layer, 34...first high refractive index layer, 40...second columnar crystal, 40a...tapered portion, 40b...constant diameter portion, 42...second low refractive index layer, 44...second high refractive index layer, 50...first light-emitting layer, 52...second light-emitting layer, 60...third columnar crystal, 62...third low refractive index layer, 64...third high refractive index layer, 70...fourth columnar crystal, 72...fourth low refractive index layer, 74... Fourth high refractive index layer, 80...first electrode, 82...second electrode, 100, 110...photonic crystal structure, 200, 210...light emitting device, 210R...red light source, 210G...green light source, 210B...blue light source, 900...projector, 902R...first optical element, 902G...second optical element, 902B...third optical element, 904R...first light modulation device, 904G...second light modulation device, 904B...third light modulation device, 906...cross dichroic prism, 908...projection device, 910...screen

Claims (7)

forming a plurality of first columnar sections and a plurality of second columnar sections each having a height smaller than that of the first columnar sections;
growing a first columnar crystal on each of the plurality of first columnar portions and growing a second columnar crystal on each of the plurality of second columnar portions;
having
In the step of growing the first columnar crystals and the second columnar crystals,
a first low refractive index layer and a first high refractive index layer having a refractive index higher than that of the first low refractive index layer are alternately laminated to grow the first columnar crystals;
a second low refractive index layer and a second high refractive index layer having a refractive index higher than that of the second low refractive index layer are alternately laminated to grow the second columnar crystals;
The first low refractive index layer and the second high refractive index layer are disposed at a first position in a stacking direction of the first low refractive index layer and the first high refractive index layer,
A method for manufacturing a photonic crystal structure, comprising: arranging the second low refractive index layer and the first high refractive index layer at a second position different from the first position in the stacking direction. In claim 1 ,
A method for manufacturing a photonic crystal structure, wherein in the step of forming the first columnar portion and the second columnar portion, the first columnar portion and the second columnar portion are formed by crystal growth. In claim 2 ,
A method for manufacturing a photonic crystal structure, wherein a diameter of the first columnar section is larger than a diameter of the second columnar section. A plurality of first columnar portions;
A plurality of second columnar portions each having a height smaller than that of the first columnar portions;
a first columnar crystal provided in each of the plurality of first columnar portions;
second columnar crystals provided in each of the plurality of second columnar portions;
having
The first columnar crystals are
A first low refractive index layer;
a first high refractive index layer having a refractive index higher than that of the first low refractive index layer;
having
the first low refractive index layers and the first high refractive index layers are alternately stacked,
The second columnar crystals are
A second low refractive index layer;
a second high refractive index layer having a refractive index higher than that of the second low refractive index layer;
having
the second low refractive index layer and the second high refractive index layer are alternately stacked,
the first low-refractive index layer and the second high-refractive index layer are provided at a first position in a stacking direction of the first low-refractive index layer and the first high-refractive index layer,
The photonic crystal structure, wherein the second low refractive index layer and the first high refractive index layer are provided at a second position different from the first position in the stacking direction. In claim 4 ,
A photonic crystal structure, wherein the diameter of the first columnar portion is larger than the diameter of the second columnar portion. The photonic crystal structure according to claim 4 or 5 ,
a light emitting layer provided on the first columnar crystal;
A light emitting device comprising: A projector comprising the light emitting device according to claim 6 .

Images