JP2018133516A - Light-emitting device, projector, and method for manufacturing light-emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light-emitting device which can suppress light from being leaked on a substrate side.SOLUTION: A light-emitting device comprises: a substrate; and a laminate provided on the substrate and having a plurality of pillar parts. The plurality of pillar parts each have: a first semiconductor layer; a second semiconductor layer different, in conductivity type, from the first semiconductor layer; and an active layer provided between the first and second semiconductor layers. In the light-emitting device, a first layer and a second layer higher than the first layer in refraction index are provided between the pillar parts adjacent to each other. The first layer is provided between the substrate and the second layer. The distance between the substrate and a boundary of the first and second layers is smaller than the distance between the active layer and the substrate.SELECTED DRAWING: Figure 1

Description

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

  Semiconductor lasers are expected as next-generation light sources with high brightness. In particular, semiconductor lasers using nanostructures (nanocolumns) are expected to be able to achieve high-power light emission with a narrow emission angle due to the effect of the photonic crystals of the nanostructures. Such a semiconductor laser is applied as a light source of a projector, for example.

For example, Patent Document 1 discloses an GaN nanocolumn having an n-type layer (n-type semiconductor layer), an active layer provided on the n-type layer, and a p-type layer (p-type semiconductor layer) provided on the active layer. And a compound semiconductor device including a SiO ₂ film provided around a GaN nanocolumn.

JP 2008-166567 A

However, in the GaN nanocolumn as described above, the SiO ₂ film is provided on both sides of the n-type semiconductor layer and the active layer, and the average refractive index of the n-type semiconductor layer and the SiO ₂ film ( In some cases, the average refractive index in the direction orthogonal to the stacking direction of the n-type semiconductor layer and the active layer cannot be made sufficiently smaller than the average refractive index of the active layer and the SiO ₂ film. Therefore, in the light emitting device including the GaN nanocolumn as described above, light generated in the active layer may leak to the substrate side.

  One of the objects according to some aspects of the present invention is to provide a light emitting device capable of suppressing light from leaking to the substrate side. Another object of some embodiments of the present invention is to provide a projector including the light-emitting device. One of the objects according to some embodiments of the present invention is to provide a method for manufacturing a light-emitting device capable of suppressing light from leaking to the substrate side.

The light emitting device according to the present invention is
A substrate;
A laminated body provided on the substrate and having a plurality of columnar parts;
Including
The columnar part is
A first semiconductor layer;
A second semiconductor layer having a conductivity type different from that of the first semiconductor layer;
An active layer provided between the first semiconductor layer and the second semiconductor layer;
Have
A first layer and a second layer having a refractive index higher than the refractive index of the first layer are provided between the adjacent columnar portions,
The first layer is provided between the base and the second layer,
The distance between the boundary between the first layer and the second layer and the substrate is smaller than the distance between the active layer and the substrate.

  In such a light emitting device, for example, when the distance between the boundary between the first layer and the second layer and the substrate is larger than the distance between the active layer and the substrate, Compared to the case where the refractive index of the second layer is lower than or equal to the refractive index of the first layer, the average refractive index of the first layer and the first semiconductor layer is larger than the average refractive index of the second layer and the active layer. Can also be reduced. Therefore, in such a light-emitting device, light generated in the active layer can be prevented from leaking to the substrate side.

In the light emitting device according to the present invention,
A void may be provided in the first layer.

  In such a light emitting device, the average refractive index of the air gap and the first semiconductor layer can be made smaller than the average refractive index of the second layer and the active layer. Therefore, in such a light emitting device, it is possible to more reliably suppress light generated in the active layer from leaking to the substrate side.

In the light emitting device according to the present invention,
The columnar part is
A first columnar section having the first semiconductor layer;
A second columnar section having the first semiconductor layer, the active layer, and the second semiconductor layer;
Have
The first columnar part may be provided between the base body and the second columnar part.

  In such a light emitting device, for example, the crystal quality of the active layer can be improved as compared with the case where the second columnar portion does not have the first semiconductor layer.

In the light emitting device according to the present invention,
The first layer is a silicon oxide layer;
The second layer may be a titanium oxide layer.

  In such a light emitting device, the refractive index of the second layer can be made higher than the refractive index of the first layer.

In the light emitting device according to the present invention,
A plasmon generating layer that generates surface plasmon resonance between the adjacent second semiconductor layers;
The second layer may be provided between the first layer and the plasmon generating layer.

  In such a light emitting device, light can be enhanced.

In the light emitting device according to the present invention,
A plasmon generating layer that generates surface plasmon resonance between the adjacent first semiconductor layers;
The plasmon generating layer may be provided between the base and the first layer.

  In such a light emitting device, light can be enhanced.

The projector according to the present invention is
A light emitting device according to the present invention is included.

  Such a projector can include the light emitting device according to the present invention.

A method for manufacturing a light emitting device according to the present invention includes:
A plurality of columnar shapes including a first semiconductor layer, a second semiconductor layer having a conductivity type different from that of the first semiconductor layer, and an active layer provided between the first semiconductor layer and the second semiconductor layer on a base body Forming a laminate having a portion;
Forming a first layer between adjacent columnar parts;
After the step of forming the first layer, a step of forming a second layer having a refractive index higher than the refractive index of the first layer between the adjacent columnar portions;
Including
In the step of forming the first layer,
The first layer is formed such that a distance between the boundary between the first layer and the second layer and the base is smaller than a distance between the active layer and the base.

  In such a method for manufacturing a light emitting device, it is possible to manufacture a light emitting device capable of suppressing light from leaking to the substrate side.

A method for manufacturing a light emitting device according to the present invention includes:
Forming a laminated body having a plurality of first columnar portions including a first semiconductor layer on a substrate;
Forming a first layer between the adjacent first columnar parts;
After the step of forming the first layer, an end portion of the first columnar portion includes a second semiconductor layer having a conductivity type different from that of the first semiconductor layer, and the first semiconductor layer and the second semiconductor layer. Forming a second columnar portion having an active layer provided therebetween;
Forming a second layer having a refractive index higher than the refractive index of the first layer between the adjacent second columnar parts;
Including
In the step of forming the first layer,
The first layer is formed such that a distance between the boundary between the first layer and the second layer and the base is smaller than a distance between the active layer and the base.

  In such a method for manufacturing a light emitting device, the aspect ratio of the first columnar portion when forming the first layer can be reduced. Thus, in such a method for manufacturing a light emitting device, the first layer can be formed so that no gap is generated between adjacent columnar portions.

In the method for manufacturing a light emitting device according to the present invention,
The step of forming the second layer includes
The step of forming the first portion of the second layer between the adjacent first columnar portions after the step of forming the first layer and before the step of forming the second columnar portion. When,
Forming a second portion of the second layer between the adjacent second columnar portions;
You may have.

  In such a method for manufacturing a light emitting device, the second columnar portion can be formed using the first portion of the second layer as a mask.

A method for manufacturing a light emitting device according to the present invention includes:
The first layer is a silicon oxide layer;
The second layer may be a titanium oxide layer.

  In such a method for manufacturing a light emitting device, the refractive index of the second layer is set higher than that of the first layer, and a titanium oxide layer suitable as a mask for forming the second columnar portion is used as a mask. Can do.

A method for manufacturing a light emitting device according to the present invention includes:
In the step of forming the first portion,
After forming the first portion so as to cover the end portion of the first columnar portion, the first portion is formed between the adjacent first columnar portions by etching a part of the first portion. The end portion of the first columnar portion may be exposed.

  In such a light emitting device manufacturing method, even if the end of the first columnar part is covered by the first part, the end of the first columnar part can be exposed, so that the end of the first columnar part is exposed to the end of the first columnar part. A second columnar part can be formed.

Sectional drawing which shows typically the light-emitting device which concerns on 1st Embodiment. The flowchart for demonstrating the manufacturing process of the light-emitting device which concerns on 1st Embodiment. Sectional drawing which shows typically the manufacturing process of the light-emitting device which concerns on 1st Embodiment. Sectional drawing which shows typically the manufacturing process of the light-emitting device which concerns on 1st Embodiment. Sectional drawing which shows typically the light-emitting device which concerns on the modification of 1st Embodiment. Sectional drawing which shows typically the light-emitting device which concerns on 2nd Embodiment. The flowchart for demonstrating the manufacturing process of the light-emitting device which concerns on 2nd Embodiment. Sectional drawing which shows typically the manufacturing process of the light-emitting device which concerns on 2nd Embodiment. Sectional drawing which shows typically the manufacturing process of the light-emitting device which concerns on 2nd Embodiment. Sectional drawing which shows typically the manufacturing process of the light-emitting device which concerns on 2nd Embodiment. Sectional drawing which shows typically the light-emitting device which concerns on 3rd Embodiment. Sectional drawing which shows typically the light-emitting device which concerns on the modification of 3rd Embodiment. FIG. 10 is a diagram schematically illustrating a projector according to a fourth embodiment.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. 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 essential constituent requirements of the present invention.

1. 1. First embodiment 1.1. First, the light emitting device according to the first embodiment will be described with reference to the drawings. FIG. 1 is a cross-sectional view schematically showing a light emitting device 100 according to the first embodiment.

  As illustrated in FIG. 1, the light emitting device 100 includes a base body 10, a stacked body 20, a first layer 40, a second layer 42, a first electrode 50, and a second electrode 52.

  The base 10 has, for example, a plate shape. The base 10 is, for example, a Si substrate or a sapphire substrate.

  The stacked body 20 is provided on the base 10 (on the base 10). The stacked body 20 includes a buffer layer 22 and a columnar portion 30.

The buffer layer 22 is provided on the substrate 10. The buffer layer 22 is, for example, a first conductivity type (for example, n-type) GaN layer (specifically, a GaN layer doped with Si).
In the illustrated example, a mask layer 60 for forming the columnar portion 30 is provided on the buffer layer 22.

  The columnar part 30 is provided on the buffer layer 22. A plurality of columnar portions 30 are provided. The cross-sectional shape of the columnar part 30 (cross-sectional shape in a direction orthogonal to the stacking direction of the stacked body 20) is, for example, a circle, a polygon (for example, a hexagon), or the like. The diameter of the columnar part 30 (inscribed circle diameter in the case of a polygon) is, for example, on the order of nm, and specifically 10 nm or more and 500 nm or less. The columnar part 30 is also called, for example, a nanocolumn, nanowire, nanorod, or nanopillar. The size of the stacked body 20 of the columnar portion 30 in the stacking direction (hereinafter also simply referred to as “stacking direction”) is, for example, 0.1 μm or more and 5 μm or less. The plurality of columnar portions 30 are separated from each other. The interval between adjacent columnar portions 30 is, for example, not less than 1 nm and not more than 500 nm.

  In the present invention, “upper” means a direction away from the substrate 10 when viewed from the stacked body 20 in the stacking direction, and “lower” means closer to the substrate 10 when viewed from the stacked body 20 in the stacking direction. It is a direction.

The plurality of columnar portions 30 are arranged at a predetermined pitch in a predetermined direction in a plan view (as viewed from the stacking direction). In such a periodic structure, a light confinement effect can be obtained at the photonic band edge wavelength λ determined by the pitch, the diameter of each part, and the refractive index of each part. In the light emitting device 100, the light generated in the active layer 35 of the columnar portion 30 includes the wavelength λ, and thus can exhibit the effect of a photonic crystal. The average refractive index, at a certain position the stacking direction, when the columnar portion 30 of the dielectric constant epsilon ₁ is arranged in a filling factor phi, as the dielectric constant of the layer between the columnar portion 30 adjacent epsilon ₂ , (Ε ₁ × φ + ε ₂ (1−φ)). The dielectric constant ε ₁ is a dielectric constant of the first semiconductor layer 32, the active layer 34, or the second semiconductor layer 36 of the columnar part 30. The dielectric constant ε ₂ is the dielectric constant of the first layer 40 or the second layer 42.

  The columnar part 30 includes a first semiconductor layer 32, an active layer 34, and a second semiconductor layer 36.

  The first semiconductor layer 32 is provided on the buffer layer 22. The first semiconductor layer 32 and the buffer layer 22 are, for example, a first conductivity type (eg, n-type) GaN layer (specifically, a GaN layer doped with Si). In the illustrated example, the size of the first semiconductor layer 32 in the stacking direction is larger than the size of the second semiconductor layer 36 in the stacking direction.

  The active layer 34 is provided on the first semiconductor layer 32. The active layer 34 is provided between the first semiconductor layer 32 and the second semiconductor layer 36. The active layer 34 is a layer that can emit light when current is injected. The active layer 34 has, for example, a quantum well structure composed of a GaN layer and an InGaN layer. The number of GaN layers and InGaN layers constituting the active layer 34 is not particularly limited.

  The second semiconductor layer 36 is provided on the active layer 34. The second semiconductor layer 36 is a layer having a conductivity type different from that of the first semiconductor layer 32. The second semiconductor layer 36 is, for example, a second conductivity type (for example, p-type) GaN layer (specifically, a GaN layer doped with Mg). The semiconductor layers 32 and 36 are cladding layers having a function of confining light in the active layer 34 (suppressing light leakage from the active layer 34).

In the light emitting device 100, the p-type second semiconductor layer 36, the active layer 34 not doped with impurities, and the n-type first semiconductor layer 32 constitute a pin diode. Each of the first semiconductor layer 32 and the second semiconductor layer 36 is a layer having a band gap larger than that of the active layer 34. In the light emitting device 100, when a forward bias voltage of a pin diode is applied between the first electrode 50 and the second electrode 52 (current is injected), recombination of electrons and holes occurs in the active layer 34. This recombination causes light emission. The light generated in the active layer 34 propagates in the direction orthogonal to the stacking direction by the semiconductor layers 32 and 36, and forms a standing wave in the direction orthogonal to the stacking direction by the effect of the photonic crystal by the columnar portion 30; The active layer 34 receives a gain and oscillates. The light emitting device 100 emits the + 1st order diffracted light and the −1st order diffracted light as laser light in the stacking direction (to the second electrode 52 side and the substrate 10 side).

  Although not shown, a reflective layer may be provided between the base 10 and the buffer layer 22 or below the base 10. The reflective layer is, for example, a DBR (Distributed Bragg Reflector) layer. The light generated in the active layer 34 can be reflected by the reflective layer, and the light emitting device 100 can emit light only from the second electrode 52 side.

The first layer 40 is provided on the mask layer 60. Alternatively, the mask layer 60 may be removed before the first layer 40 is formed, and the first layer 40 may be provided on the buffer layer 22. The first layer 40 is provided between the base 10 and the second layer 42. The first layer 40 is provided between adjacent columnar portions 30. The first layer 40 is, for example, a silicon oxide layer (for example, SiO ₂ layer), a silicon oxynitride layer (for example, SiON layer), an aluminum oxide layer (for example, Al ₂ O ₃ layer), a hafnium oxide layer (for example, HfO ₂ layer), or the like. It is. For example, the refractive index of SiO ₂ is 1.46, the refractive index of Al ₂ O ₃ is 1.77, and the refractive index of HfO ₂ is 1.94. The first layer 40 is, for example, a first embedded layer embedded between adjacent columnar portions 30.

The second layer 42 is provided on the first layer 40. The second layer 42 is provided between the adjacent columnar portions 30. The second layer 42 has a refractive index higher than that of the first layer 40. The second layer 42 is, for example, a titanium oxide layer (for example, TiO ₂ layer), a zirconium oxide layer (for example, ZrO ₂ layer), a silicon nitride layer (for example, SiN layer), or the like. For example, the refractive index of TiO ₂ (amorphous) is 2.5, the refractive index of TiO ₂ (rutile) is 2.985, the refractive index of ZrO ₂ is 2.2, and the refractive index of SiN is 2 0.036. For example, the first layer 40 is a silicon oxide layer, and the second layer 42 is a titanium oxide layer. The second layer 42 is, for example, a second embedded layer embedded between adjacent columnar portions 30.

  The second layer 42 is provided around the active layer 34 in plan view. In the illustrated example, the active layer 34 and the second semiconductor layer 36 are in contact with the second layer 42. The first semiconductor layer 32 has a portion in contact with the first layer 40 and a portion in contact with the second layer 42.

  A distance D1 between the boundary between the first layer 40 and the second layer 42 and the substrate 10 is smaller than a distance D2 between the active layer 34 and the substrate 10. The distance D1 is a distance between the second layer 42 and the substrate 10. The space between adjacent columnar portions 30 is filled with, for example, the first layer 40 and the second layer 42. In the illustrated example, the upper surface of the second layer 42 and the upper surface of the second semiconductor layer 36 are flush with each other. Although not shown, the upper surface of the second layer 42 may be positioned lower than the upper surface of the second semiconductor layer 36 (depressed from the upper surface of the second semiconductor layer 36).

  In the present embodiment, the distance D1 between the boundary between the first layer 40 and the second layer 42 and the base 10 is equal to the boundary between the first layer 40 and the second layer 42, the base 10, The distance D2 between the active layer 34 and the substrate 10 is the minimum distance in the stacking direction between the active layer 34 and the substrate 10.

The first electrode 50 is provided under the base 10. The substrate 10 may be in ohmic contact with the first electrode 50. The first electrode 50 is electrically connected to the first semiconductor layer 32. In the illustrated example, the first electrode 50 is electrically connected to the first semiconductor layer 32 via the base 10 and the buffer layer 22. The first electrode 50 is one electrode for injecting a current into the active layer 34. As the first electrode 50, for example, a Ti layer, an Al layer, and an Au layer stacked in this order from the base 10 side, a transparent electrode such as ITO (Indium Tin Oxide), or the like is used.

  In the case where the substrate 10 is insulative, the first electrode 50 may be provided on the buffer layer 22 (in a region where the columnar portion 30 of the buffer layer 22 is not provided) although not shown. .

  The second electrode 52 is provided on the second semiconductor layer 36 and the second layer 42. The second electrode 52 is electrically connected to the second semiconductor layer 36. The second electrode 52 is the other electrode for injecting current into the active layer 34. As the second electrode 52, for example, a transparent electrode such as ITO is used. Thereby, the light emitted from the active layer 34 can be transmitted through the second electrode 52 and emitted.

  Although not shown, a contact layer may be provided between the second electrode 52 and the second semiconductor layer 36 and between the second electrode 52 and the second layer 42. The contact layer may be in ohmic contact with the second electrode 52. The contact layer may be a p-type GaN layer.

  For example, the light emitting device 100 has the following characteristics.

  In the light emitting device 100, the first layer 40 and the second layer 42 having a refractive index higher than the refractive index of the first layer 40 are provided between the adjacent columnar portions 30. The distance D1 provided between the base 10 and the second layer 42 and between the boundary between the first layer 40 and the second layer 42 and the base 10 is the distance between the active layer 34 and the base 10. It is smaller than D2. Therefore, in the light emitting device 100, for example, compared with the case where the distance D1 is larger than the distance D2, or when the refractive index of the second layer 42 is lower than or equal to the refractive index of the first layer 40, The average refractive index of the first semiconductor layer 32 can be made sufficiently smaller than the average refractive index of the second layer 42 and the active layer 34. Therefore, in the light emitting device 100, it is possible to suppress light generated in the active layer 34 from leaking to the base 10 side when propagating in a direction orthogonal to the stacking direction. For example, the refractive index of the substrate is generally higher than the average refractive index including columnar portions (average refractive index in the direction orthogonal to the stacking direction), and light may easily leak to the substrate side. Then, it can suppress that light leaks to the base | substrate 10 side.

  Furthermore, in the light emitting device 100, for example, in order to prevent dislocations accompanying lattice distortion caused by the difference in lattice constant between the substrate 10 and the buffer layer 22 from reaching the active layer 34, The size in the stacking direction is made larger than the size in the stacking direction of the second semiconductor layer 36. Therefore, for example, due to the fact that the active layer 34 is positioned above the center of the columnar portion 30, it is assumed that the light intensity peak in the stacking direction (the direction in which the light generated in the active layer 34 is orthogonal to the stacking direction). In the light emitting device 100, the average refractive index between the first layer 40 and the columnar part 30 is set to be equal to the second layer 42 and the columnar part 30. Therefore, the peak of the light intensity in the stacking direction can be matched with the position of the active layer 34.

  In the light emitting device 100, the first layer 40 is a silicon oxide layer, and the second layer 42 is a titanium oxide layer. Therefore, in the light emitting device 100, the refractive index of the second layer 42 can be made higher than the refractive index of the first layer 40.

1.2. Method for Manufacturing Light-Emitting Device Next, a method for manufacturing the light-emitting device 100 according to the first embodiment will be described with reference to the drawings. FIG. 2 is a flowchart for explaining a method of manufacturing the light emitting device 100 according to the first embodiment. 3 and 4 are cross-sectional views schematically showing the manufacturing process of the light emitting device 100 according to the first embodiment.

  As shown in FIG. 3, the laminated body 20 is formed on the base | substrate 10 (step S11). Specifically, first, the buffer layer 22 is epitaxially grown on the substrate 10. Examples of the epitaxial growth method include a MOCVD (Metal Organic Chemical Deposition) method and an MBE (Molecular Beam Epitaxy) method.

  Next, a mask layer 60 is formed on the buffer layer 22. The mask layer 60 is, for example, a silicon oxide layer, a silicon oxynitride layer, an aluminum oxide layer, a hafnium oxide layer, a titanium, a titanium oxide layer, a zirconium oxide layer, a silicon nitride layer, or a laminated film thereof. The mask layer 60 is formed by film formation by MOCVD method or MBE method, and patterning by photolithography technique and etching technique.

  Next, using the mask layer 60 as a mask, the first semiconductor layer 32, the active layer 34, and the second semiconductor layer 36 are epitaxially grown in this order on the buffer layer 22 by MOCVD, MBE, or the like. Thereby, the columnar part 30 can be formed. The laminated body 20 can be formed by the above process.

  As shown in FIG. 4, the 1st layer 40 is formed between the columnar parts 30 adjacent (step S12). The first layer 40 is formed by, for example, a spin coating method, an ALD (Atomic Layer Deposition) method, or the like. In this step, the first layer 40 is formed so that the thickness of the first layer 40 is smaller than the thickness of the first semiconductor layer 32. That is, the first layer 40 is formed so that the distance D1 is smaller than the distance D2. Thus, in the method for manufacturing the light emitting device 100, the height of the boundary between the first layer 40 and the second layer 42 with respect to the active layer 34 is easily adjusted by adjusting the thickness of the first layer 40. I can do this.

Next, the second layer 42 is formed between the adjacent columnar portions 30 (step S13). The second layer 42 is formed by, for example, a spin coat method or an ALD method. Note that after the second layer 42 is formed, for example, etching or CMP (Chemical Mechanical) is performed.
The upper surface of the second semiconductor layer 36 and the upper surface of the second layer 42 may be flush with each other by polishing.

  As shown in FIG. 1, the first layer 40 and the second layer 42 are patterned into a predetermined shape (step S14). The patterning is performed by, for example, photolithography and etching.

  Next, the first electrode 50 is formed under the base 10, and the second electrode 52 is formed on the second semiconductor layer 36 and the second layer 42 (step S15). The electrodes 50 and 52 are formed by, for example, a vacuum evaporation method. The order of forming the first electrode 50 and the second electrode 52 is not particularly limited.

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

  In the method for manufacturing the light emitting device 100, the light emitting device 100 capable of suppressing light from leaking to the base 10 side can be manufactured.

1.3. Modification of Light Emitting Device Next, a light emitting device according to a modification of the first embodiment will be described with reference to the drawings. FIG. 5 is a cross-sectional view schematically showing a light emitting device 110 according to a modification of the first embodiment. Hereinafter, in the light emitting device 110 according to the modified example of the first embodiment, members having the same functions as those of the constituent members of the light emitting device 100 according to the first embodiment described above will be denoted by the same reference numerals and detailed description thereof will be given. Is omitted.

  As shown in FIG. 5, the light emitting device 110 is different from the above-described light emitting device 100 in that the first layer 40 is provided with the gap 2.

  The gap 2 is provided at the end of the first layer 40 on the base 10 side. For example, when the first layer 40 is formed, the gap 2 is formed by setting the aspect ratio of the columnar portion 30 on the mask layer 60 so that the material for film formation does not enter.

  The light emitting device 110 can obtain the same effect as the light emitting device 100.

  In the light emitting device 110, the first layer 40 is provided with the gap 2. Therefore, in the light emitting device 110, the average refractive index between the gap 2 and the first semiconductor layer 32 can be made smaller than the average refractive index between the second layer 42 and the active layer 34. Therefore, in the light emitting device 110, the light generated in the active layer 34 can be more reliably suppressed from leaking to the base 10 side.

  The first layer 40 may be an air layer. In this case, a gap is provided between (in contact with) the active layer 34 and the substrate 10.

2. Second Embodiment 2.1. Next, a light emitting device according to a second embodiment will be described with reference to the drawings. FIG. 6 is a cross-sectional view schematically showing the light emitting device 200 according to the second embodiment. Hereinafter, in the light emitting device 200 according to the second embodiment, members having the same functions as those of the constituent members of the light emitting device 100 according to the first embodiment described above are denoted by the same reference numerals, and detailed description thereof is omitted. .

  As shown in FIG. 6, the light emitting device 200 is different from the light emitting device 100 described above in that the columnar portion 30 includes a first columnar portion 30 a and a second columnar portion 30 b.

  The first columnar part 30 a is provided on the buffer layer 22. The first columnar part 30a is provided between the base 10 and the second columnar part 30b. The first columnar part 30 a has a first semiconductor layer 32. In the illustrated example, the first columnar portion 30 a is configured by the first semiconductor layer 32.

  The second columnar part 30b is provided on the first columnar part 30a. The second columnar part 30 b has an active layer 34 and a second semiconductor layer 36. In the illustrated example, the second columnar portion 30 b includes a first semiconductor layer 32, an active layer 34, and a second semiconductor layer 36, and is constituted by the active layer 34 and the semiconductor layers 32 and 36. A distance D1 between the boundary between the first layer 40 and the second layer 42 and the base body 10 is smaller than a distance D3 between the second columnar portion 30b and the base body 10.

  The second layer 42 has, for example, a first portion 42a and a second portion 42b. The first portion 42a is a portion that is formed before the second columnar portion 30b is formed, and the second portion 42b is a portion that is formed after the second columnar portion 30b is formed (for details, see FIG. Refer to “2.2. Manufacturing method of light emitting device” described later).

  In the light emitting device 200, the same effect as that of the light emitting device 100 can be obtained.

  In the light emitting device 200, the columnar portion 30 includes a first columnar portion 30 a having the first semiconductor layer 32, and a second columnar portion 30 b having the first semiconductor layer 32, the active layer 34, and the second semiconductor layer 36. The first columnar portion 30a is provided between the base 10 and the second columnar portion 30b. Therefore, in the light emitting device 200, the crystal quality of the active layer 34 can be improved as compared with, for example, the case where the second columnar portion 30b does not include the first semiconductor layer 32 (details will be described later in “2” Refer to “2. Manufacturing method of light-emitting device”).

2.2. Method for Manufacturing 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. FIG. 7 is a flowchart for explaining a method for manufacturing the light emitting device 200 according to the second embodiment. 8-10 is sectional drawing which shows typically the manufacturing process of the light-emitting device 200 which concerns on 2nd Embodiment. Hereinafter, in the method for manufacturing the light emitting device 200 according to the second embodiment, differences from the example of the light emitting device 100 according to the first embodiment described above will be described, and description of similar points will be omitted or simplified.

  As shown in FIG. 8, the laminated body 20a including the first columnar portion 30a and the buffer layer 22 is formed on the base 10 (step S21). The first columnar portion 30a is formed by the MOCVD method, the MBE method, or the like using the mask layer 60 as a mask.

  Next, the first layer 40 is formed between the adjacent first columnar portions 30a (step S22).

  Next, the first portion 42a of the second layer 42 is formed between the adjacent first columnar portions 30a (step S23). Specifically, first, as shown in FIG. 9, the first portion 42a is formed so as to cover the upper surface 31 of the first columnar portion 30a. The first portion 42a is formed by, for example, a spin coating method or an ALD method. Next, as shown in FIG. 10, a part of the first portion 42a is etched to form the first portion 42a between the adjacent first columnar portions 30a, and the upper surface 31 of the first columnar portion 30a is exposed. . Through the above steps, the first portion 42a of the second layer 42 can be formed. The upper surface 31 is an end of the first columnar portion 30a opposite to the base 10 side.

  In the example shown in FIG. 10, the upper surface 31 of the first columnar portion 30a is located above the upper surface 43 of the first portion 42a (the side opposite to the base 10 side). Although not shown, the upper surface 31 may be flush with the upper surface 43, or may be located below the upper surface 43 (base 10 side).

  Next, as shown in FIG. 6, the second columnar portion 30b is formed on the upper surface 31 of the first columnar portion 30a (step S24). Thereby, the columnar part 30 which has the 1st columnar part 30a and the 2nd columnar part 30b can be formed. The second columnar portion 30b is formed by the MOCVD method, the MBE method, or the like using the first portion 42a of the second layer 42 as a mask.

  Next, the second portion 42b of the second layer 42 is formed between the adjacent second columnar portions 30b (step S25). Thereby, the second layer 42 having the first portion 42a and the second portion 42b can be formed. The second portion 42b is formed by, for example, a spin coat method or an ALD method.

  Next, the first layer 40 and the second layer 42 are patterned into a predetermined shape (step S26).

  Next, the first electrode 50 and the second electrode 52 are formed (step S27).

  The light emitting device 200 can be manufactured through the above steps.

  In the method for manufacturing the light emitting device 200, it is possible to manufacture the light emitting device 200 capable of suppressing light from leaking to the base 10 side.

  In the method for manufacturing the light emitting device 200, the first columnar portion 30a is formed, then the first layer 40 is formed, and then the second columnar portion 30b is formed on the upper surface 31 of the first columnar portion 30a. Therefore, in the manufacturing method of the light emitting device 200, the aspect ratio of the first columnar portion 30a when forming the first layer 40 is set to the aspect ratio of the columnar portion 30 when forming the first layer 40 in the manufacturing method of the light emitting device 100. The ratio can be made smaller. Thereby, in the manufacturing method of the light emitting device 200, the first layer 40 can be formed so that no gap is generated between the adjacent columnar portions 30.

  In the method for manufacturing the light emitting device 200, the first portion 42a of the second layer 42 is formed between the adjacent first columnar portions 30a before forming the second columnar portions 30b. Therefore, in the method for manufacturing the light emitting device 200, the second columnar portion 30b can be formed using the first portion 42a of the second layer 42 as a mask.

  In the method for manufacturing the light emitting device 200, the first layer 40 is a silicon oxide layer, and the second layer 42 is a titanium oxide layer. Therefore, in the method for manufacturing the light emitting device 200, a titanium oxide layer suitable as a mask for forming the second columnar portion 30b is masked while the refractive index of the second layer 42 is higher than the refractive index of the first layer 40. It can be.

  In the method for manufacturing the light emitting device 200, after forming the first portion 42a of the second layer 42 so as to cover the upper surface 31 of the first columnar portion 30a, a part of the first portion 42a is etched to be adjacent to the first portion 42a. A first portion 42a is formed between the columnar portions 30a, and the upper surface 31 of the first columnar portion 30a is exposed. Therefore, in the method for manufacturing the light emitting device 200, even if the upper surface 31 of the first columnar part 30a is covered by the first portion 42a, the upper surface 31 of the first columnar part 30a can be exposed, so the first columnar part 30a. A second columnar portion 30b can be formed on the upper surface 31 of the first electrode.

  Further, in the light emitting device 200, the first columnar part 30 a includes the first semiconductor layer 32, and the second columnar part 30 b includes the first semiconductor layer 32, the active layer 34, and the second semiconductor layer 36. It has a columnar part 30b. Therefore, in the light emitting device 200, even if the upper surface 31 is subjected to etching damage when the upper surface 31 of the first columnar portion 30a is exposed, the first semiconductor layer 32 is further formed on the upper surface 31. Compared with the case where the two columnar portions 30 b do not have the first semiconductor layer 32, the crystal quality of the active layer 34 can be improved.

  Although not shown, the first portion 42a of the second layer 42 is not formed before the second columnar portion 30b is formed, and the second layer 42 is formed after the second columnar portion 30b is formed. Also good.

3. Third Embodiment 3.1. Light Emitting Device Next, a light emitting device according to a third embodiment will be described with reference to the drawings. FIG. 11 is a cross-sectional view schematically showing a light emitting device 300 according to the third embodiment. Hereinafter, in the light emitting device 300 according to the third embodiment, members having the same functions as those of the constituent members of the light emitting device 100 according to the first embodiment described above are denoted by the same reference numerals, and detailed description thereof is omitted. .

  As shown in FIG. 11, the light emitting device 300 is different from the light emitting device 100 described above in that it includes a plasmon generating layer 70.

  The plasmon generation layer 70 is provided on the second layer 42. The second layer 42 is provided between the first layer 40 and the plasmon generation layer 70. The plasmon generation layer 70 is provided between the adjacent second semiconductor layers 36. An insulating layer 80 is provided on the side surface of the columnar part 30. An insulating layer 80 is provided between the second semiconductor layer 36 and the plasmon generation layer 70. Furthermore, the insulating layer 80 is also provided on the mask layer 60. In the illustrated example, the second electrode 52 is provided on the upper surface of each of the plurality of columnar portions 30, and the plasmon generation layer 70 covers the second electrode 52. The plasmon generation layer 70 is not provided between the adjacent first semiconductor layers 32 and between the adjacent active layers 34.

  The plasmon generation layer 70 is, for example, an Al layer, an Ag layer, an Au layer, or the like. When the light generated in the active layer 34 is ultraviolet light, the plasmon generation layer 70 is preferably an Al layer. When the light generated in the active layer 34 is blue light, the plasmon generating layer 70 is preferably an Ag layer. When the light generated in the active layer 34 is red light, the plasmon generation layer 70 is preferably an Au layer. The plasmon generation layer 70 may be a layer containing fine metal particles such as Al, Ag, and Au. The insulating layer 80 is, for example, a silicon oxide layer.

  The plasmon generating layer 70 is a layer that generates surface plasmon resonance. Carriers injected into the active layer 34 are combined with surface plasmons generated in the plasmon generating layer 70 and converted into light with high efficiency. Further, since the plurality of columnar portions 30 and the plasmon generation layer 70 are periodically arranged in a predetermined direction, they can be extracted as light having a narrow emission angle in the stacking direction. In addition, since the plurality of columnar portions 30 and the first layer 40 and the second layer 42 are periodically arranged in a predetermined direction, they have a photonic crystal effect and are generated in the active layer 34. Light is also subjected to the photonic crystal effect, so that light with higher efficiency and narrow emission angle can be realized. Moreover, in order to express said effect, the 1st layer 40 and the 2nd layer 42 are not necessarily required, and it does not need to be provided with the 1st layer 40 and the 2nd layer 40, but is provided with only one layer. It does not matter. When the light generated in the active layer 34 is red light, the period of the columnar part 30 is preferably 200 nm or more and 250 nm or less.

  In the light emitting device 300, the same effect as that of the light emitting device 100 can be obtained.

  The light emitting device 300 includes a plasmon generation layer 70 that generates surface plasmon resonance between adjacent second semiconductor layers 36, and a second layer 42 is provided between the first layer 40 and the plasmon generation layer 70. It has been. For this reason, in the light emitting device 300, the light directed toward the second electrode 52 among the light radiated in the stacking direction can be reflected by the plasmon generation layer 70 and the second electrode 52, and the light is emitted from the base 10 side. be able to. In the light emitting device 300, the plasmon generation layer 70 is not provided between the adjacent first semiconductor layers 32 and between the adjacent active layers 34. Compared with the case where the plasmon generation layer 70 is also provided between the layers 34, the light can be enhanced while reducing the light loss due to the plasmon generation layer 70. Therefore, the light emitting device 300 can have high efficiency.

  In the light emitting device 300, an insulating layer 80 is provided between the second semiconductor layer 36 and the plasmon generation layer 70. Therefore, in the light emitting device 300, it is possible to prevent the current injected into the second semiconductor layer 36 from leaking to the plasmon generation layer 70.

  Note that the light emitting devices 100, 110, and 200 described above may include the plasmon generation layer 70 as in the light emitting device 300.

3.2. Method for Manufacturing Light-Emitting Device Next, a method for manufacturing the light-emitting device 300 according to the third embodiment will be described.

  In the method for manufacturing the light emitting device 300, the insulating layer 80 is formed on the surface of the columnar portion 30 by sputtering, CVD (Chemical Vapor Deposition), or the like. Next, the upper surface of the columnar portion 30 is exposed by etching or CMP. Further, after the second layer 42 is formed, the plasmon generation layer 70 is formed by spin coating, ALD, CVD (Chemical Vapor Deposition), sputtering, or the like.

  Except for the above, the method for manufacturing the light emitting device 300 is basically the same as the method for manufacturing the light emitting device 100 described above. Therefore, the detailed description is abbreviate | omitted.

3.3. Modification of Light Emitting Device Next, a light emitting device according to a modification of the third embodiment will be described with reference to the drawings. FIG. 12 is a cross-sectional view schematically showing a light emitting device 310 according to a modification of the third embodiment. Hereinafter, in the light emitting device 310 according to the third embodiment, members having the same functions as those of the light emitting device 100 according to the first embodiment and the light emitting device 300 according to the third embodiment are denoted by the same reference numerals. A detailed description thereof will be omitted.

  In the light emitting device 300, as shown in FIG. 11, the plasmon generation layer 70 is provided between the adjacent second semiconductor layers 36.

  On the other hand, in the light emitting device 310, as shown in FIG. 12, the plasmon generation layer 70 is provided between the adjacent first semiconductor layers 32. The plasmon generating layer 70 is provided between the base 10 and the first layer 40. The plasmon generation layer 70 is not provided between the adjacent active layers 34 and between the adjacent second semiconductor layers 36.

  The light emitting device 310 can be manufactured by forming the plasmon generating layer 70 before forming the first layer 40.

  The light emitting device 310 can obtain the same effect as the light emitting device 100.

  The light emitting device 310 includes a plasmon generation layer 70 that generates surface plasmon resonance between adjacent first semiconductor layers 32, and the plasmon generation layer 70 is provided between the base 10 and the first layer 40. . Therefore, in the light emitting device 300, the light traveling toward the substrate 10 among the light radiated in the stacking direction can be reflected by the plasmon generation layer 70, and the light can be emitted from the second electrode 52 side. In the light emitting device 300, the plasmon generation layer 70 is not provided between the adjacent active layers 34 and between the adjacent second semiconductor layers 36, and therefore, between the adjacent active layers 34 and the adjacent second layers. Compared with the case where the plasmon generation layer 70 is also provided between the semiconductor layers 36, it is possible to enhance light while reducing the light loss due to the plasmon generation layer 70. Accordingly, the light emitting device 310 can have high efficiency.

  Although not shown, the plasmon generation layer 70 may be provided only between the adjacent active layers 34.

4). Projector Next, a projector according to a fourth embodiment will be described with reference to the drawings. FIG. 13 is a diagram schematically illustrating a projector 900 according to the fourth embodiment.

  The projector according to the present invention includes the light emitting device according to the present invention. Hereinafter, a projector 900 including the light emitting device 100 as the light emitting device according to the present invention will be described.

  As shown in FIG. 13, the projector 900 includes a red light source 100R that emits red light, green light, and blue light, a green light source 100G, and a blue light source 100B. Each of the red light source 100R, the green light source 100G, and the blue light source 100B includes, for example, a plurality of light emitting devices 100 arranged in an array in a direction orthogonal to the stacking direction, and the base 10 is used as a common substrate in the plurality of light emitting devices 100. Is. The number of the light emitting devices 100 constituting each of the light sources 100R, 100G, and 100B is not particularly limited. For the sake of convenience, in FIG. 13, the casing constituting the projector 900 is omitted, and the light sources 100R, 100G, and 100B are simplified.

  The projector 900 further includes lens arrays 902R, 902G, and 902B, transmissive liquid crystal light valves (light modulation devices) 904R, 904G, and 904B, and a projection lens (projection device) 908.

  Light emitted from the light sources 100R, 100G, and 100B is incident on the lens arrays 902R, 902G, and 902B. Light emitted from the light sources 100R, 100G, and 100B is collected by the lens arrays 902R, 902G, and 902B, and can be superimposed (partially superimposed), for example. Thereby, the liquid crystal light valves 904R, 904G, and 904B can be irradiated with good uniformity.

  The light condensed by the lens arrays 902R, 902G, and 902B is incident on the liquid crystal light valves 904R, 904G, and 904B. Each of the liquid crystal light valves 904R, 904G, and 904B modulates incident light according to image information. The projection lens 908 enlarges and projects an image (image) formed by the liquid crystal light valves 904R, 904G, and 904B onto a screen (display surface) 910.

  In addition, the projector 900 can include a cross dichroic prism (color light combining unit) 906 that combines light emitted from the liquid crystal light valves 904R, 904G, and 904B and guides the light to the projection lens 908.

  The three color lights modulated by the liquid crystal light valves 904R, 904G, and 904B are incident on the cross dichroic prism 906. This prism is formed by bonding four right-angle prisms, and a dielectric multilayer film that reflects red light and a dielectric multilayer film that reflects blue light are arranged in a cross shape on the inner surface thereof. These dielectric multilayer films combine the three color lights to form light representing a color image. The synthesized light is projected onto the screen 910 by the projection lens 908 which is a projection optical system, and an enlarged image is displayed.

  The light sources 100R, 100G, and 100B control the liquid crystal light valves 904R, 904G, and 904B by controlling (modulating) the light emitting devices 100 constituting the light sources 100R, 100G, and 100B as image pixels according to image information. You may form an image | video directly, without using. The projection lens 908 may enlarge and project the image formed by the light sources 100R, 100G, and 100B onto the screen 910.

  In the above example, a transmissive liquid crystal light valve is used as the light modulation device. However, a light valve other than liquid crystal may be used, or a reflective light valve may be used. Examples of such a light valve include a reflection type liquid crystal light valve and a digital micromirror device (Digital Micromirror Device). Further, the configuration of the projection optical system is appropriately changed depending on the type of light valve used.

  Further, the light source 100R, 100G, 100B has scanning means that is an image forming apparatus that displays an image of a desired size on the display surface by causing the light from the light source 100R, 100G, 100B to scan on the screen. The present invention can also be applied to a light source device of a simple scanning image display device (projector).

  In the present invention, a part of the configuration may be omitted within a range having the characteristics and effects described in the present application, or each embodiment or modification may be combined.

  The present invention includes configurations that are substantially the same as the configurations described in the embodiments (for example, configurations that have the same functions, methods, and results, or configurations that have the same objects and effects). In addition, the invention includes a configuration in which a non-essential part of the configuration described in the embodiment is replaced. In addition, the present invention includes a configuration that exhibits the same operational effects as the configuration described in the embodiment or a configuration that can achieve the same object. Further, the invention includes a configuration in which a known technique is added to the configuration described in the embodiment.

DESCRIPTION OF SYMBOLS 2 ... Space | gap, 10 ... Base | substrate, 20, 20a ... Laminated body, 22 ... Buffer layer, 30 ... Columnar part, 30a ... 1st columnar part, 30b ... 2nd columnar part, 32 ... 1st semiconductor layer, 34 ... Active layer , 36 ... second semiconductor layer, 40 ... first layer, 42 ... second layer, 42a ... first part, 42b ... second part, 50 ... first electrode, 52 ... second electrode, 60 ... mask layer, 70 Plasmon generating layer, 80 insulating layer, 100 light emitting device, 100R, 100G, 100B light source, 110, 200, 300, 310 light emitting device, 900 projector, 902R, 902G, 902B lens array, 904R, 904G 904B ... Liquid crystal light valve, 906 ... Cross dichroic prism, 908 ... Projection lens, 910 ... Screen

Claims (12)

A substrate;
A laminated body provided on the substrate and having a plurality of columnar parts;
Including
The columnar part is
A first semiconductor layer;
A second semiconductor layer having a conductivity type different from that of the first semiconductor layer;
An active layer provided between the first semiconductor layer and the second semiconductor layer;
Have
A first layer and a second layer having a refractive index higher than the refractive index of the first layer are provided between the adjacent columnar portions,
The first layer is provided between the base and the second layer,
The light emitting device, wherein a distance between the boundary between the first layer and the second layer and the substrate is smaller than a distance between the active layer and the substrate. In claim 1,
The light emitting device, wherein the first layer is provided with a gap. In claim 1 or 2,
The columnar part is
A first columnar section having the first semiconductor layer;
A second columnar section having the first semiconductor layer, the active layer, and the second semiconductor layer;
Have
The first columnar part is a light emitting device provided between the base and the second columnar part. In any one of Claims 1 thru | or 3,
The first layer is a silicon oxide layer;
The light emitting device, wherein the second layer is a titanium oxide layer. In any one of Claims 1 thru | or 4,
A plasmon generating layer that generates surface plasmon resonance between the adjacent second semiconductor layers;
The light emitting device, wherein the second layer is provided between the first layer and the plasmon generating layer. In any one of Claims 1 thru | or 4,
A plasmon generating layer that generates surface plasmon resonance between the adjacent first semiconductor layers;
The light emitting device, wherein the plasmon generating layer is provided between the base and the first layer.   A projector comprising the light emitting device according to claim 1. A plurality of columnar shapes including a first semiconductor layer, a second semiconductor layer having a conductivity type different from that of the first semiconductor layer, and an active layer provided between the first semiconductor layer and the second semiconductor layer on a base body Forming a laminate having a portion;
Forming a first layer between adjacent columnar parts;
After the step of forming the first layer, a step of forming a second layer having a refractive index higher than the refractive index of the first layer between the adjacent columnar portions;
Including
In the step of forming the first layer,
Light emission in which the first layer is formed such that the distance between the boundary between the first layer and the second layer and the substrate is smaller than the distance between the active layer and the substrate. Device manufacturing method. Forming a laminated body having a plurality of first columnar portions including a first semiconductor layer on a substrate;
Forming a first layer between the adjacent first columnar parts;
After the step of forming the first layer, an end portion of the first columnar portion includes a second semiconductor layer having a conductivity type different from that of the first semiconductor layer, and the first semiconductor layer and the second semiconductor layer. Forming a second columnar portion having an active layer provided therebetween;
Forming a second layer having a refractive index higher than the refractive index of the first layer between the adjacent second columnar parts;
Including
In the step of forming the first layer,
Light emission in which the first layer is formed such that the distance between the boundary between the first layer and the second layer and the substrate is smaller than the distance between the active layer and the substrate. Device manufacturing method. In claim 9,
The step of forming the second layer includes
The step of forming the first portion of the second layer between the adjacent first columnar portions after the step of forming the first layer and before the step of forming the second columnar portion. When,
Forming a second portion of the second layer between the adjacent second columnar portions;
A method for manufacturing a light emitting device. In claim 10,
The first layer is a silicon oxide layer;
The light emitting device, wherein the second layer is a titanium oxide layer. In claim 10 or 11,
In the step of forming the first portion,
After forming the first portion so as to cover the end portion of the first columnar portion, the first portion is formed between the adjacent first columnar portions by etching a part of the first portion. A method for manufacturing a light emitting device, wherein an end portion of the first columnar portion is exposed.

Images