Light emitting device and projector

Abstract

To provide a light emitting device that can increase the intensity of light to be emitted.SOLUTION: A light emitting device has a substrate, and a laminate that is provided on a substrate surface of the substrate and has a plurality of columnar parts. The columnar part has a light emitting layer. The light emitting layer has a first end on the substrate side and a second end on the opposite side of the substrate. A first cross-section of the columnar part in a direction orthogonal to a lamination direction of the laminate includes the first end. A second cross-section of the columnar part in the direction orthogonal to the lamination direction is a cross-section including the light emitting layer at a position on the opposite side of the substrate with respect to the first cross-section in the lamination direction. In a plan view seen from the lamination direction, the center of the first cross-section is different in position from the center of the second cross-section.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a light emitting device and a projector. [Background technology]

[0002] Semiconductor lasers are expected to become the next generation of high-brightness light sources. In particular, semiconductor lasers that incorporate nanocolumns are expected to be able to achieve high-output light emission with a narrow radiation angle due to the photonic crystal effect of the nanocolumns.

[0003] For example, Patent Document 1 describes an optical device including a plurality of columnar crystals made of a III-V group semiconductor having an active layer. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2018-142660 A Summary of the Invention [Problem to be solved by the invention]

[0005] In such optical devices, it is desirable to increase the intensity of the emitted light. [Means for solving the problem]

[0006] One aspect of the light emitting device according to the present invention is A substrate; a laminate provided on a substrate surface of the substrate and having a plurality of columnar portions; having The columnar portion has a light emitting layer, the light-emitting layer has a first end on a side of the substrate and a second end on an opposite side to the substrate; a first cross section of the columnar portion in a direction perpendicular to the stacking direction of the stacked body includes the first end, a second cross section of the columnar portion in a direction perpendicular to the stacking direction is a cross section including the light emitting layer at a position on the opposite side to the substrate in the stacking direction from the first cross section, In a plan view seen from the stacking direction, The center of the first cross section is at a different position from the center of the second cross section.

[0007] One aspect of the projector according to the present invention is The present invention has one aspect of the light emitting device. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a cross-sectional view illustrating a light emitting device according to an embodiment of the present invention. [Diagram 2] FIG. 3 is a cross-sectional view showing a schematic view of a columnar portion of the light emitting device according to the embodiment. [Diagram 3] FIG. 2 is a schematic cross-sectional view of a columnar portion of the light emitting device according to the embodiment. [Figure 4] 5A to 5C are cross-sectional views each showing a schematic process for manufacturing the light emitting device according to the embodiment. [Diagram 5] 5A to 5C are cross-sectional views each showing a schematic process for manufacturing the light emitting device according to the embodiment. [Figure 6] 1A to 1C are perspective views each showing a schematic diagram of a manufacturing process for the light emitting device according to the embodiment; [Figure 7] 5A to 5C are cross-sectional views each showing a schematic process for manufacturing the light emitting device according to the embodiment. [Figure 8] FIG. 1 is a diagram illustrating a projector according to an embodiment of the present invention. [Figure 9] Cross-sectional TEM image of the columnar part. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Preferred embodiments of the present invention will be described in detail below with reference to the drawings. Note that the embodiments described below do not unduly limit the contents of the present invention described in the claims. In addition, not all of the configurations described below are necessarily essential components of the present invention.

[0010] 1. Light-emitting device 1.1. Overall structure First, the light emitting device according to the present embodiment will be described with reference to the drawings. Fig. 1 is a cross-sectional view that shows a schematic diagram of a light emitting device 100 according to the present embodiment.

[0011] 1, the light emitting device 100 includes, for example, a substrate 10, a laminate 20, a first electrode 40, and a second electrode 42. The light emitting device 100 is a semiconductor laser.

[0012] The substrate 10 is, for example, a Si substrate, a GaN substrate, a sapphire substrate, a SiC substrate, etc. The substrate 10 has a substrate surface 12. In the illustrated example, the substrate surface 12 is the upper surface of the substrate 10. The substrate surface 12 has a perpendicular line P.

[0013] The laminate 20 is provided on the substrate surface 12 of the substrate 10. In the illustrated example, the laminate 20 is provided on the substrate 10. The laminate 20 has, for example, a buffer layer 22 and a columnar portion 30.

[0014] In this specification, in the stacking direction of the laminate 20 (hereinafter also simply referred to as the "stacking direction"), when the light emitting layer 34 is used as a reference, the direction from the light emitting layer 34 toward the second semiconductor layer 36 is described as "upper", and the direction from the light emitting layer 34 toward the first semiconductor layer 32 is described as "lower". A direction perpendicular to the stacking direction is also referred to as an "in-plane direction". The "stacking direction of the laminate 20" refers to the stacking direction of the first semiconductor layer 32 and the light emitting layer 34 of the columnar section 30. The direction of the perpendicular line P is the stacking direction.

[0015] The buffer layer 22 is provided on the substrate 10. The buffer layer 22 is, for example, a Si-doped n-type GaN layer. A mask layer 24 for forming the columnar section 30 is provided on the buffer layer 22. The mask layer 24 is, for example, a silicon oxide layer, a titanium layer, a titanium oxide layer, an aluminum oxide layer, or the like.

[0016] The columnar section 30 is provided on the buffer layer 22. The columnar section 30 has a columnar shape protruding upward from the buffer layer 22. In other words, the columnar section 30 protrudes upward from the substrate 10 via the buffer layer 22. The columnar section 30 is also called, for example, a nanocolumn, a nanowire, a nanorod, or a nanopillar. The planar shape of the columnar section 30 is, for example, a polygon or a circle.

[0017] The diameter of the columnar section 30 is, for example, 50 nm or more and 500 nm or less. By making the diameter of the columnar section 30 500 nm or less, it is possible to obtain a light-emitting layer 34 of high quality crystals and reduce distortion inherent in the light-emitting layer 34. This allows the light generated in the light-emitting layer 34 to be amplified with high efficiency.

[0018] The "diameter of the columnar portion" refers to the diameter when the planar shape of the columnar portion 30 is a circle, and refers to the diameter of the smallest inclusive circle when the planar shape of the columnar portion 30 is not a circle. For example, when the planar shape of the columnar portion 30 is a polygon, the diameter of the columnar portion 30 refers to the diameter of the smallest circle that includes the polygon, and when the planar shape of the columnar portion 30 is an ellipse, the diameter of the smallest circle that includes the ellipse.

[0019] A plurality of columnar sections 30 are provided. The interval between adjacent columnar sections 30 is, for example, 1 nm or more and 500 nm or less. The plurality of columnar sections 30 are arranged at a predetermined pitch in a predetermined direction in a plan view seen from the stacking direction. The plurality of columnar sections 30 are arranged, for example, in a triangular lattice or square lattice pattern. The plurality of columnar sections 30 can exhibit the effect of a photonic crystal.

[0020] The "pitch of the columnar portion" is the distance between the centers of adjacent columnar portions 30 along a predetermined direction. When the planar shape of the columnar portion 30 is a circle, the "center of the columnar portion" is the center of the circle, and when the planar shape of the columnar portion 30 is a shape other than a circle, the center of the smallest inclusive circle. For example, when the planar shape of the columnar portion 30 is a polygon, the center of the columnar portion 30 is the center of the smallest circle that includes the polygon inside, and when the planar shape of the columnar portion 30 is an ellipse, the center of the smallest circle that includes the ellipse inside.

[0021] Moreover, the "center of the cross section" refers to the center of a circle when the cross section of the columnar section 30 is circular in plan view from the stacking direction, and the center of the smallest inclusive circle when the cross section of the columnar section 30 is not circular. For example, when the cross section of the columnar section 30 is polygonal, the center of the cross section of the columnar section 30 is the center of the smallest circle that includes the polygon, and when the cross section of the columnar section 30 is elliptical, the center of the smallest circle that includes the ellipse.

[0022] The columnar section 30 has a first semiconductor layer 32, a light emitting layer 34, and a second semiconductor layer 36. The detailed shape and the like of the columnar section 30 will be described later.

[0023] The first semiconductor layer 32 is provided on the buffer layer 22. The first semiconductor layer 32 is provided between the substrate 10 and the light emitting layer 34. The first semiconductor layer 32 is, for example, an n-type GaN layer doped with Si.

[0024] The light emitting layer 34 is provided on the first semiconductor layer 32. The light emitting layer 34 is provided between the first semiconductor layer 32 and the second semiconductor layer 36. The light emitting layer 34 generates light when a current is injected into it. The light emitting layer 34 has, for example, a well layer 33 and a barrier layer 35. The well layer 33 and the barrier layer 35 are i-type semiconductor layers that are not intentionally doped with impurities. The well layer 33 is, for example, an InGaN layer. The barrier layer 35 is, for example, a GaN layer. The light emitting layer 34 has an MQW (Multiple Quantum Well) structure composed of the well layer 33 and the barrier layer 35.

[0025] The number of well layers 33 and barrier layers 35 constituting the light-emitting layer 34 is not particularly limited. For example, only one well layer 33 may be provided, in which case the light-emitting layer 34 has a SQW (Single Quantum Well) structure.

[0026] The second semiconductor layer 36 is provided on the light emitting layer 34. The second semiconductor layer 36 is a layer of a different conductivity type from the first semiconductor layer 32. The second semiconductor layer 36 is, for example, a p-type GaN layer doped with Mg. The first semiconductor layer 32 and the second semiconductor layer 36 are cladding layers having the function of confining light in the light emitting layer 34.

[0027] Although not shown, an OCL (Optical Confinement Layer) made of an i-type InGaN layer may be provided between the first semiconductor layer 32 and the light emitting layer 34. The second semiconductor layer 36 may have an EBL (Electron Blocking Layer) made of a p-type AlGaN layer.

[0028] In the light emitting device 100, a p-type second semiconductor layer 36 and an i-type light emitting layer not doped with impurities are The optical layer 34 and the n-type first semiconductor layer 32 form a pin diode. In the light-emitting device 100, when a forward bias voltage of the pin diode is applied between the first electrode 40 and the second electrode 42, a current is injected into the light-emitting layer 34, and recombination of electrons and holes occurs in the light-emitting layer 34. This recombination generates light. The light generated in the light-emitting layer 34 propagates in the in-plane direction, forms a standing wave due to the effect of the photonic crystal of the multiple columnar sections 30, and receives gain in the light-emitting layer 34 to oscillate as a laser. The light-emitting device 100 then emits the +1st order diffracted light and the -1st order diffracted light as laser light in the stacking direction.

[0029] Although not shown, a reflective layer may be provided between the substrate 10 and the buffer layer 22 or under the substrate 10. The reflective layer is, for example, a DBR (Distributed Bragg Reflector) layer. The reflective layer can reflect light generated in the light-emitting layer 34, and the light-emitting device 100 can emit light only from the second electrode 42 side.

[0030] The first electrode 40 is provided on the buffer layer 22. The buffer layer 22 may be in ohmic contact with the first electrode 40. The first electrode 40 is electrically connected to the first semiconductor layer 32. In the illustrated example, the first electrode 40 is electrically connected to the first semiconductor layer 32 via the buffer layer 22. The first electrode 40 is one of the electrodes for injecting a current into the light-emitting layer 34. As the first electrode 40, for example, a layer formed by laminating a Cr layer, a Ni layer, and an Au layer in this order from the buffer layer 22 side is used.

[0031] The second electrode 42 is provided on the second semiconductor layer 36. The second electrode 42 is provided on the side of the laminate 20 opposite to the substrate 10. The second electrode 42 is electrically connected to the second semiconductor layer 36. The second semiconductor layer 36 may be in ohmic contact with the second electrode 42. The second electrode 42 is the other electrode for injecting a current into the light-emitting layer 34. For example, ITO (indium tin oxide) or the like is used as the second electrode 42.

[0032] 1.2. Detailed shape of the column Fig. 2 is a cross-sectional view showing a schematic view of the columnar section 30. As shown in Fig. 2, the first semiconductor layer 32 has a c-plane 2. The c-plane 2 is parallel to the substrate surface 12. The c-plane 2 is perpendicular to a perpendicular line P to the substrate surface 12. The first semiconductor layer 32, the light emitting layer 34, and the second semiconductor layer 36 are, for example, Group III nitride semiconductors and have a wurtzite crystal structure.

[0033] The light-emitting layer 34 has a first end 34a on the substrate 10 side and a second end 34b on the opposite side to the substrate 10. The second end 34b is the end on the second electrode 42 side. The first cross section 30a and the second cross section 30b are cross sections obtained by cutting the columnar section 30 in the in-plane direction. That is, the first cross section 30a and the second cross section 30b are cross sections in the in-plane direction of the columnar section 30. The first cross section 30a includes the first end 34a. The second cross section 30b includes the second end 34b. The second cross section 30b is a cross section including the light-emitting layer 34 at a position on the opposite side to the substrate 10 from the first cross section 30a in the stacking direction.

[0034] Here, FIG. 3 is a diagram showing the first cross section 30a and the second cross section 30b. As shown in FIG. 3, in a plan view seen from the stacking direction, a part of the first cross section 30a does not overlap with the second cross section 30b. In a plan view seen from the stacking direction, a part of the second cross section 30b does not overlap with the first cross section 30a. In addition, in a plan view seen from the stacking direction, the center C1 of the first cross section 30a and the center C2 of the second cross section 30b are at different positions. The center C1 is separated from the center C2. As shown in FIG. 2, a straight line L1 passing through the center C1 of the first cross section 30a and the center C2 of the second cross section 30b is inclined at an inclination angle α with respect to a perpendicular line P of the substrate surface 12. The columnar section 30 is bent at a first end 34a of the light-emitting layer 34.

[0035] In this embodiment, the shape of the first cross section 30a in a plan view seen from the stacking direction and the stacking direction The shape of the second cross section 30b in plan view from the stacking direction is the same, but this is not limited thereto, and the shape of the first cross section 30a and the shape of the second cross section 30b may be different. For example, the area of ​​the first cross section 30a and the area of ​​the second cross section 30b may be different in plan view from the stacking direction. For example, the area of ​​the first cross section 30a may be smaller than the area of ​​the second cross section 30b.

[0036] In the present embodiment, the second cross section 30b includes the second end 34b, but is not limited thereto, and the second cross section 30b may be a cross section including the light emitting layer 34 at a position on the opposite side of the substrate 10 from the first cross section 30a in the stacking direction, and the center C2 may be located at a different position from the center C1 of the first cross section 30a in plan view in the stacking direction. In other words, the second cross section 30b is a cross section of the columnar section 30 between the first end 34a and the second end 34b, and the position of the center C2 in plan view is different from the center C1 of the first cross section 30a.

[0037] The second semiconductor layer 36 has a third end 36a on the substrate 10 side and a fourth end 36b on the opposite side to the substrate 10. The fourth end 36b is the end on the second electrode 42 side. The third cross section 30c and the fourth cross section 30d are cross sections obtained by cutting the columnar section 30 in the in-plane direction. That is, the third cross section 30c and the fourth cross section 30d are cross sections in the in-plane direction of the columnar section 30. The third cross section 30c includes the third end 36a. The fourth cross section 30d includes the fourth end 36b. The inclination angle of the straight line L2 passing through the center C3 of the third cross section 30c and the center C4 of the fourth cross section 30d with respect to the perpendicular line P is smaller than the inclination angle α of the straight line L1 with respect to the perpendicular line P. In the illustrated example, the straight line L2 is parallel to the perpendicular line P, and the inclination angle of the straight line L2 with respect to the perpendicular line P is 0°. In the illustrated example, the third cross section 30c overlaps with the second cross section 30b. The center C3 overlaps with the center C2. The columnar section 30 is bent at the second end 34b of the light emitting layer 34. The light emitting layer 34 of the columnar section 30 is inclined with respect to the perpendicular line P.

[0038] The fifth cross section 30e is a cross section when the columnar section 30 is cut in the in-plane direction. That is, the fifth cross section 30e is a cross section of the columnar section 30 in the in-plane direction. The fifth cross section 30e includes the center C5 of the c-plane 2. In a plan view seen from the stacking direction, the center C5 of the c-plane 2 is shifted from the center C6 of the fifth cross section 30e of the columnar section 30. In other words, the center C1 is separated from the center C2. The center C5 is in a different position from the center C6.

[0039] The sixth cross section 30f is a cross section of the columnar section 30 cut in the stacking direction. That is, the sixth cross section 30f is a cross section of the columnar section 30 in the stacking direction. The sixth cross section 30f includes the center C5 of the c-plane 2. The sixth cross section 30f is a cross section of the columnar section 30 shown in FIG. 2. In the sixth cross section 30f, the first semiconductor layer 32 has a first facet surface 4 and a second facet surface 6. The facet surfaces 4 and 6 are connected to the c-plane 2. The facet surfaces 4 and 6 are inclined with respect to the c-plane 2. The second facet surface 6 has an inclination angle with respect to the c-plane 2 different from that of the first facet surface 4. In the illustrated example, the inclination angle β of the first facet surface 4 with respect to the c-plane 2 is smaller than the inclination angle γ of the second facet surface 6 with respect to the c-plane 2. Note that the first facet surface 4 and the second facet surface 6 are continuous with each other in a plan view seen from the stacking direction.

[0040] The well layer 33 of the light-emitting layer 34 has a fifth end 33a on the substrate 10 side and a sixth end 33b on the opposite side to the substrate 10. The sixth end 33b is the end on the second electrode 42 side. The seventh cross section 30g and the eighth cross section 30h are cross sections obtained by cutting the columnar section 30 in the in-plane direction. That is, the seventh cross section 30g and the eighth cross section 30h are cross sections in the in-plane direction of the columnar section 30. The seventh cross section 30g includes the fifth end 33a. The eighth cross section 30h includes the sixth end 33b. The inclination angle of the straight line L3 passing through the center C7 of the seventh cross section 30g and the center C8 of the eighth cross section 30h with respect to the perpendicular line P is smaller than the inclination angle α of the straight line L1 with respect to the perpendicular line P. In the illustrated example, the straight line L3 is parallel to the perpendicular line P, and the inclination angle of the straight line L3 with respect to the perpendicular line P is 0°.

[0041] 1.3. Effects In the light emitting device 100, the light emitting layer 34 has a first end 34a on the substrate 10 side and a second end 34b on the opposite side to the substrate 10, the first cross section 30a in the in-plane direction of the columnar section 30 includes the first end 34a, and the second cross section 30b in the in-plane direction of the columnar section 30 is a cross section including the light emitting layer 34 at a position on the opposite side to the substrate 10 from the first cross section 30a in the stacking direction. In a plan view seen from the stacking direction, the center C1 of the first cross section 30a is different from the center C2 of the second cross section 30b. Therefore, in the light emitting device 100, the light confinement coefficient can be made smaller and the emission coefficient can be made larger, for example, compared to a case in which the center position of the first cross section 30a and the center position of the second cross section 30b are the same. This makes it possible to increase the intensity of the emitted light.

[0042] In the light emitting device 100, the second cross section 30b includes the second end 34b, and in a plan view seen from the stacking direction, a part of the first cross section 30a does not overlap with the second cross section 30b, and a part of the second cross section 30b does not overlap with the first cross section 30a. Therefore, in the light emitting device 100, the light confinement coefficient can be made smaller and the emission coefficient can be made larger, compared to a case in which the entire surface of the first cross section 30a overlaps with the second cross section 30b. This makes it possible to increase the intensity of the emitted light.

[0043] In the light emitting device 100, the columnar section 30 has a first semiconductor layer 32 and a second semiconductor layer 36 having a conductivity type different from that of the first semiconductor layer 32, the light emitting layer 34 is provided between the first semiconductor layer 32 and the second semiconductor layer 36, and the first semiconductor layer 32 is provided between the substrate 10 and the light emitting layer 34. Therefore, in the light emitting device 100, a current can be injected into the light emitting layer 34 through the first semiconductor layer 32 and the second semiconductor layer 36.

[0044] The light emitting device 100 has a second electrode 42 provided on the side opposite to the substrate 10 of the laminate 20, and the second semiconductor layer 36 has a third end 36a on the substrate 10 side and a fourth end 36b on the second electrode 42 side. The inclination angle of a straight line L2 passing through a center C3 of a third cross section 30c in the in-plane direction of the columnar section 30 including the third end 36a and a center C4 of a fourth cross section 30d in the in-plane direction of the columnar section 30 including the fourth end 36b with respect to a perpendicular line P of the substrate surface 12 is smaller than the inclination angle α of a straight line L1 passing through a center C1 of the first cross section 30a and a center C2 of the second cross section 30b with respect to a perpendicular line P of the substrate surface 12. Therefore, in the light emitting device 100, the flatness of the second electrode 42 can be increased compared to a case where the inclination angle of the straight line L2 with respect to the perpendicular line P is larger than the inclination angle α. This allows a current to be injected into the light emitting layer 34 with good uniformity.

[0045] In the light emitting device 100, the first semiconductor layer 32 has a c-plane 2, and in a plan view seen from the stacking direction, a center C5 of the c-plane 2 is misaligned with a center C6 of a fifth cross section 30e in the in-plane direction of the columnar portion 30, the center C5 of the c-plane 2 being included in the cross section. Therefore, in the light emitting device 100, the columnar portion 30 can be bent at the first end 34a of the light emitting layer 34.

[0046] In the light emitting device 100, in a sixth cross section 30f in the stacking direction of the columnar section 30 including the center C5 of the c-plane 2, the first semiconductor layer 32 has a first facet surface 4 and a second facet surface 6 having a different inclination angle with respect to the first facet surface 4 and the c-plane 2. Therefore, in the light emitting device 100, the columnar section 30 can be bent at the first end 34a of the light emitting layer 34.

[0047] In the light emitting device 100, the light emitting layer 34 has a well layer 33 and a barrier layer 35, and the well layer 33 has a fifth end 33a on the substrate 10 side and a sixth end 33b on the opposite side to the substrate 10. The inclination angle of a straight line L3 passing through a center C7 of a seventh cross section 30g in the in-plane direction including the fifth end 33a and a center C8 of an eighth cross section 30h in the in-plane direction of the columnar section 30 including the sixth end 33b, with respect to a perpendicular line P to the substrate surface 12, is smaller than the inclination angle α of a straight line L1 passing through a center C1 of the first cross section 30a and a center C2 of the second cross section 30b, with respect to a perpendicular line P to the substrate surface 12. Therefore, the light emitting device 10 At angle α=0, the uniformity of the strain applied to the well layer 33 can be increased compared to when the inclination angle of the straight line L3 with respect to the perpendicular line P is greater than the inclination angle α. This makes it possible to suppress variations in the emission wavelength.

[0048] 2. Manufacturing method of light-emitting device Next, a method for manufacturing the light emitting device 100 according to this embodiment will be described with reference to the drawings. Fig. 4 and Fig. 5 are cross-sectional views that typically show the manufacturing process of the light emitting device 100 according to this embodiment. Fig. 6 is a perspective view that typically shows the manufacturing process of the light emitting device 100 according to this embodiment. Fig. 7 is a cross-sectional view that typically shows the manufacturing process of the light emitting device 100 according to this embodiment.

[0049] 4, the buffer layer 22 is epitaxially grown on the substrate 10. Examples of the epitaxial growth method include physical deposition methods such as MBE (Molecular Beam Epitaxy).

[0050] Next, a mask layer 24 is formed on the buffer layer 22. The mask layer 24 is formed by, for example, deposition using an electron beam deposition method or a sputtering method, and patterning. The patterning is performed by, for example, photolithography and etching.

[0051] 5, the first semiconductor layer 32 is epitaxially grown on the buffer layer 22 using the mask layer 24 as a mask. Examples of a method for epitaxial growth include physical deposition methods such as MBE.

[0052] As shown in Fig. 6, the first semiconductor layer 32 is grown by rotating the substrate 10 on which the buffer layer 22 and the mask layer 24 are formed about a rotation axis Q while shifting the rotation axis Q from the peak position T of the molecular beam intensity. In the MBE method, the target is irradiated with a molecular beam in an ultra-high vacuum, so the position where the molecular beam is irradiated and the distribution of the intensity can be controlled. This is an effect that cannot be obtained by vapor phase growth methods such as the MOCVD (Metal Organic Chemical Vapor Deposition) method.

[0053] In this manner, as shown in FIG. 5, a first semiconductor layer 32 can be grown, which has a c-plane 2 and facets 4 and 6 having inclination angles β and γ different from each other.

[0054] As shown in Fig. 7, the light emitting layer 34 is epitaxially grown on the first semiconductor layer 32. Examples of a method for epitaxial growth include physical deposition methods such as MBE. When the light emitting layer 34 contains InGaN, the InGaN is concentrated near the center C5 of the c-plane 2 where distortion is small. Therefore, the light emitting layer 34 grows at an angle with respect to the substrate surface 12. The light emitting layer 34 is grown, for example, by aligning the rotation axis Q with the peak position T of the molecular beam intensity.

[0055] As shown in FIG. 1, the second semiconductor layer 36 is epitaxially grown on the light emitting layer 34. Examples of the epitaxial growth method include physical deposition methods such as MBE. The second semiconductor layer 36 is grown, for example, by aligning the rotation axis Q with the peak position T of the molecular beam intensity. For example, the second semiconductor layer 36 does not include an InGaN layer, and therefore is unlikely to be inclined with respect to the substrate surface 12. This process allows the formation of a stacked body 20 having a columnar portion 30.

[0056] Next, a first electrode 40 is formed on the buffer layer 22, and a second electrode 42 is formed on the second semiconductor layer 36. The first electrode 40 and the second electrode 42 are formed by, for example, a vacuum deposition method. The order in which the first electrode 40 and the second electrode 42 are formed is not particularly limited. Thereafter, the substrate 10 is cut into a predetermined shape.

[0057] Through the above steps, the light emitting device 100 can be manufactured.

[0058] 3. Projector Next, a projector according to this embodiment will be described with reference to the drawings. Fig. 8 is a diagram showing a schematic diagram of a projector 900 according to this embodiment.

[0059] The projector 900 includes, for example, a light emitting device 100 as a light source.

[0060] Projector 900 has a housing (not shown) and red light source 100R, green light source 100G, and blue light source 100B that are provided in the housing and emit red light, green light, and blue light, respectively. For convenience, red light source 100R, green light source 100G, and blue light source 100B are simplified in FIG. 8.

[0061] 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 in 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.

[0062] The light emitted from red light source 100R is incident on first optical element 902R. The light emitted from red light source 100R is collected by first optical element 902R. Note that first optical element 902R may have a function other than collecting light. The same applies to second optical element 902G and third optical element 902B described later.

[0063] 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 in accordance with 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.

[0064] The light emitted from green light source 100G is incident on second optical element 902G. The light emitted from green light source 100G is collected by second optical element 902G.

[0065] 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 in accordance with 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.

[0066] The light emitted from blue light source 100B is incident on third optical element 902B. The light emitted from blue light source 100B is collected by third optical element 902B.

[0067] 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 in accordance with 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.

[0068] 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 guides the combined light to the projection device 908.

[0069] 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 a cross dichroic prism 906. The cross dichroic prism 906 is formed by bonding four right-angle prisms together, and a dielectric multilayer film that reflects red light and a dielectric multilayer film that reflects blue light are disposed on its inner surface. The three color lights are synthesized by these dielectric multilayer films to form light that represents a color image. The synthesized light is then projected by a projection device 908 onto a screen 910, and an enlarged image is displayed.

[0070] Note that red light source 100R, green light source 100G, and blue light source 100B may directly form an image without using first light modulation device 904R, second light modulation device 904G, and third light modulation device 904B, by controlling light emitting device 100 as pixels of an image according to image information. Then, projection device 908 may enlarge and project the image formed by red light source 100R, green light source 100G, and blue light source 100B onto screen 910.

[0071] In the above example, a transmissive liquid crystal light valve is 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 is changed as appropriate depending on the type of light valve used.

[0072] 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.

[0073] The light emitting devices according to the above-described embodiments can be used in applications other than projectors, such as light sources for indoor and outdoor lighting, displays, laser printers, scanners, car lights, sensing devices that use light, and communication devices.

[0074] 4. Experimental Example On the substrate, a columnar portion having an n-type GaN layer, an emission layer having an i-type InGaN layer and an i-type GaN layer, and an n-type GaN layer was epitaxially grown by MBE. The growth of the n-type GaN layer was performed by shifting the rotation axis of the substrate from the peak position of the molecular beam intensity.

[0075] Fig. 9 is a cross-sectional TEM (Transmission Electron Microscope) image of the columnar portion formed as described above. As shown in Fig. 9, it was found that the light-emitting layer grew at an angle with respect to the substrate surface.

[0076] The above-described embodiment and modifications are merely examples, and the present invention is not limited to these. For example, the embodiments and modifications can be appropriately combined.

[0077] 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.

[0078] The following can be derived from the above-described embodiment and modifications.

[0079] One aspect of the light emitting device is A substrate; a laminate provided on a substrate surface of the substrate and having a plurality of columnar portions; having The columnar portion has a light emitting layer, the light-emitting layer has a first end on a side of the substrate and a second end on an opposite side to the substrate; a first cross section of the columnar portion in a direction perpendicular to the stacking direction of the stacked body includes the first end, a second cross section of the columnar portion in a direction perpendicular to the stacking direction is a cross section including the light emitting layer at a position on the opposite side to the substrate in the stacking direction from the first cross section, In a plan view seen from the stacking direction, The center of the first cross section is at a different position from the center of the second cross section.

[0080] According to this light emitting device, the intensity of the emitted light can be increased.

[0081] In one embodiment of the light emitting device, The second cross section may include the second end.

[0082] In one embodiment of the light emitting device, In a plan view seen from the stacking direction, A portion of the first cross section does not overlap with the second cross section, A portion of the second cross section may not overlap with the first cross section.

[0083] According to this light emitting device, the intensity of the emitted light can be increased.

[0084] In one embodiment of the light emitting device, The columnar portion is A first semiconductor layer; A second semiconductor layer having a conductivity type different from that of the first semiconductor layer; having the light emitting layer is provided between the first semiconductor layer and the second semiconductor layer, The first semiconductor layer may be provided between the substrate and the light emitting layer.

[0085] According to this light emitting device, a current can be injected into the light emitting layer through the first semiconductor layer and the second semiconductor layer.

[0086] In one embodiment of the light emitting device, an electrode provided on the side of the laminate opposite to the substrate; the second semiconductor layer has a third end on the substrate side and a fourth end on the electrode side; The inclination angle of a line passing through a center of a third cross section of the columnar portion including the third end in the orthogonal direction and a center of a fourth cross section of the columnar portion including the fourth end in the orthogonal direction with respect to the perpendicular to the substrate surface may be smaller than the inclination angle of a line passing through the center of the first cross section and the center of the second cross section with respect to the perpendicular to the substrate surface.

[0087] According to this light emitting device, the flatness of the electrodes can be improved.

[0088] In one embodiment of the light emitting device, the first semiconductor layer has a c-plane; In a plan view seen from the stacking direction, a center of the c-plane may be shifted from a center of a fifth cross section in the orthogonal direction of the columnar portion that includes the center of the c-plane.

[0089] According to this light emitting device, the columnar portion can be bent at the first end of the light emitting layer.

[0090] In one embodiment of the light emitting device, In a sixth cross section in the stacking direction of the columnar portion including the center of the c-plane, The first semiconductor layer is A first facet surface; a second facet having an inclination angle with respect to the first facet and the c-plane different from each other; may have the following structure:

[0091] According to this light emitting device, the columnar portion can be bent at the first end of the light emitting layer.

[0092] In one embodiment of the light emitting device, the light emitting layer has a well layer and a barrier layer, the well layer has a fifth end on a side of the substrate and a sixth end opposite the substrate; The inclination angle of a line passing through the center of a seventh cross section of the columnar portion including the fifth end in the orthogonal direction and the center of an eighth cross section of the columnar portion including the sixth end in the orthogonal direction with respect to the perpendicular to the substrate surface may be smaller than the inclination angle of a line passing through the center of the first cross section and the center of the second cross section with respect to the perpendicular to the substrate surface.

[0093] According to this light emitting device, the uniformity of the strain applied to the well layer can be improved.

[0094] One aspect of the projector is The present invention has one aspect of the light emitting device. [Explanation of symbols]

[0095] 2...c-plane, 4...first facet surface, 6...second facet surface, 10...substrate, 12...substrate surface, 20...laminated body, 22...buffer layer, 24...mask layer, 30...columnar portion, 30a...first cross section, 30b...second cross section, 30c...third cross section, 30d...fourth cross section, 30e...fifth cross section, 30f...sixth cross section, 30g...seventh cross section, 30h...eighth cross section, 32...first semiconductor layer, 33...well layer, 33a...fifth end, 33b...sixth end, 34...light-emitting layer, 34a...first end, 34b...second end, 35...barrier layer, 36...second semiconductor layer, 36a...third end, 36b...fourth end, 40...first electrode, 42...second electrode, 100...light emitting device, 100R...red light source, 100G...green light source, 100B...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

1. A substrate; a laminate provided on a substrate surface of the substrate and having a plurality of columnar portions; having The columnar portion has a light emitting layer, the light-emitting layer has a first end on a side of the substrate and a second end on an opposite side to the substrate; a first cross section of the columnar portion in a direction perpendicular to the stacking direction of the stacked body includes the first end, a second cross section of the columnar portion in a direction perpendicular to the stacking direction is a cross section including the light emitting layer at a position on an opposite side to the substrate in the stacking direction from the first cross section, In a plan view seen from the stacking direction, A light emitting device, wherein a center of the first cross section is positioned differently from a center of the second cross section.

2. In claim 1, The second cross section includes the second end.

3. In claim 1 or 2, In a plan view seen from the stacking direction, A portion of the first cross section does not overlap with the second cross section, A light emitting device, wherein a portion of the second cross section does not overlap with the first cross section.

4. In any one of claims 1 to 3, The columnar portion is A first semiconductor layer; A second semiconductor layer having a conductivity type different from that of the first semiconductor layer; having the light emitting layer is provided between the first semiconductor layer and the second semiconductor layer, The first semiconductor layer is provided between the substrate and the light emitting layer.

5. In claim 4, an electrode provided on the side of the laminate opposite to the substrate; the second semiconductor layer has a third end on the substrate side and a fourth end on the electrode side; a tilt angle of a line passing through a center of a third cross section of the columnar portion including the third end in the orthogonal direction and a center of a fourth cross section of the columnar portion including the fourth end in the orthogonal direction relative to a perpendicular line to the substrate surface is smaller than a tilt angle of a line passing through the center of the first cross section and the center of the second cross section relative to a perpendicular line to the substrate surface.

6. In claim 4 or 5, the first semiconductor layer has a c-plane; In a plan view seen from the stacking direction, the center of the c-plane is shifted from the center of a fifth cross section in the orthogonal direction of the columnar portion that includes the center of the c-plane.

7. In claim 6, In a sixth cross section in the stacking direction of the columnar portion including the center of the c-plane, The first semiconductor layer is A first facet surface; a second facet having an inclination angle with respect to the c-plane different from that of the first facet; A light emitting device comprising:

8. In any one of claims 1 to 7, the light emitting layer has a well layer and a barrier layer, the well layer has a fifth end on a side of the substrate and a sixth end on an opposite side to the substrate; a tilt angle of a line passing through a center of the fifth end of the columnar portion in a seventh cross section in the orthogonal direction including the fifth end and a center of the sixth end of the columnar portion in an eighth cross section in the orthogonal direction including the sixth end, relative to a perpendicular to the substrate surface, is smaller than a tilt angle of a line passing through the center of the first cross section and the center of the second cross section, relative to a perpendicular to the substrate surface.

9. A projector comprising the light emitting device according to claim 1 .

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