JP2019029516A - Light-emitting device and projector - Google Patents

Abstract

To provide a light-emitting device capable of suppressing leakage of light.SOLUTION: The light-emitting device includes: a substance; a plurality of columnar parts installed on the substance and capable of emitting light by injecting an electric current; a light-emitting part installed between adjacent columnar parts and having a light propagation layer for propagating the light generated at the columnar parts; and a low refraction index part installed on a side wall of the light-emitting part and having a lower refraction index than that of the light propagation layer.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a light emitting device and a projector.

  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 that a reflective layer made of a metal film provided on a substrate, a plurality of nanocolumns provided on the reflective layer, an insulator filled between adjacent nanocolumns, a nanocolumn and an insulating layer. And a p-type electrode made of a transparent electrode provided on the body, and a semiconductor light-emitting element that extracts light from the p-type electrode side or the substrate side (from the vertical direction) is described.

JP 2007-49063 A

  However, in the semiconductor light-emitting device described in Patent Document 1, light generated in the light emitting layer of the nanocolumn sometimes leaks from the lateral direction.

  One of the objects according to some embodiments of the present invention is to provide a light-emitting device capable of suppressing leakage of light. Alternatively, one of the objects according to some aspects of the present invention is to provide a projector including the above light-emitting device.

The light emitting device according to the present invention is
A substrate;
A plurality of columnar portions provided on the base body and capable of emitting light by injecting current; and a light emitting unit including a light propagation layer provided between the adjacent columnar portions to propagate light generated in the columnar portions;
A low refractive index portion provided on a side wall of the light emitting portion and having a refractive index lower than a refractive index of the light propagation layer;
including.

  In such a light emitting device, the low refractive index portion can prevent light from leaking from the side wall of the light emitting portion.

In the light emitting device according to the present invention,
The columnar part is
A first semiconductor layer;
A second semiconductor layer having a conductivity type different from that of the first semiconductor layer;
A light emitting layer provided between the first semiconductor layer and the second semiconductor layer and capable of emitting light by injecting a current;
You may have.

  In such a light emitting device, the possibility that dislocations exist in the light emitting layer can be reduced.

In the light emitting device according to the present invention,
The refractive index of the light propagation layer may be lower than the refractive index of the light emitting layer.

  In such a light emitting device, light generated in the light emitting layer easily propagates in the plane direction (direction perpendicular to the stacking direction of the first semiconductor layer and the light emitting layer) through the light propagation layer.

In the light emitting device according to the present invention,
A metal layer provided on the surface of the low refractive index portion may be included.

  In such a light emitting device, even if light generated in the light emitting layer is transmitted through the low refractive index portion, the light can be reflected on the metal layer.

In the light emitting device according to the present invention,
The first semiconductor layer is provided between the base and the light emitting layer,
The metal layer may be connected to a wiring electrically connected to the second semiconductor layer.

  In such a light emitting device, the resistance to the current injected into the second semiconductor layer can be reduced.

  In the description according to the present invention, the term “electrically connected” is used, for example, as another specific member (hereinafter “electrically connected” to “specific member (hereinafter referred to as“ A member ”)”. B member "))" and the like. In the description according to the present invention, in the case of this example, the case where the A member and the B member are in direct contact and electrically connected, and the A member and the B member are the other members. The term “electrically connected” is used as a case where the case where the terminals are electrically connected to each other is included.

In the light emitting device according to the present invention,
The low refractive index portion may be provided so as to surround the light emitting portion.

  In such a light emitting device, it is possible to more reliably prevent light from leaking.

In the light emitting device according to the present invention,
The low refractive index portion may be a distributed Bragg reflector.

  In such a light emitting device, the reflectance with respect to the light generated in the columnar portion can be increased.

In the light emitting device according to the present invention,
A transistor provided corresponding to the light emitting portion may be included.

  In such a light emitting device, the timing of light emission can be controlled for each light emitting unit by controlling the transistor.

In the light emitting device according to the present invention,
The light emitting units may be provided in an array.

  In such a light-emitting device, a self-light-emitting imager that can form an image using one light-emitting portion as a pixel can be configured.

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

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

The top view which shows typically the light-emitting device which concerns on 1st Embodiment. Sectional drawing which shows typically the light-emitting device which concerns on 1st Embodiment. Sectional drawing which shows typically the light-emitting device which concerns on 1st Embodiment. 1 is a circuit diagram of a light emitting device according to a first embodiment. The top view which shows typically the light-emitting device which concerns on 1st Embodiment. Sectional drawing which shows typically 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 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 1st modification of 1st Embodiment. The circuit diagram of the light-emitting device concerning the 2nd modification of a 1st embodiment. Sectional drawing which shows typically the light-emitting device which concerns on 2nd Embodiment. Sectional drawing which shows typically the light-emitting device which concerns on 2nd Embodiment. The top view which shows typically the light-emitting device which concerns on the modification of 2nd Embodiment. Sectional drawing which shows typically the light-emitting device which concerns on the modification of 2nd Embodiment. The figure which shows typically the projector which concerns on 3rd Embodiment. The figure which shows typically the projector which concerns on 3rd 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 plan view schematically showing the light emitting device 100 according to the first embodiment. 2 is a cross-sectional view taken along the line II-II in FIG. 1 schematically showing the light emitting device 100 according to the first embodiment. 3 is a cross-sectional view taken along the line III-III of FIG. 1 schematically showing the light emitting device 100 according to the first embodiment. FIG. 4 is a circuit diagram of the light emitting device 100 according to the first embodiment. 1 to 3 and FIGS. 5 and 6 to be described later, the X axis, the Y axis, and the Z axis are illustrated as three axes orthogonal to each other.

  As shown in FIGS. 1 to 4, the light emitting device 100 includes, for example, a base 10, semiconductor layers 20 and 22, an element isolation layer 24, a transistor 30, a light emitting unit 40, a low refractive index unit 50, Insulating layer 60, conductive layer 70, wiring 72, and drive circuits 80 and 82 are included. For convenience, the insulating layer 60 is not shown in FIG.

  As shown in FIG. 2, the base 10 includes, for example, a first substrate 12, a second substrate 14, and a semiconductor layer 16. The first substrate 12 is, for example, a printed circuit board. The second substrate 14 is provided on the first substrate 12. The second substrate 14 is, for example, a sapphire substrate, a Si substrate, a GaN substrate, or the like. The semiconductor layer 16 is provided on the second substrate 14. The semiconductor layer 16 is, for example, an i-type GaN layer.

  The semiconductor layer 20 is provided on the base 10 (on the semiconductor layer 16 in the illustrated example). The semiconductor layer 20 is, for example, an n-type GaN layer (specifically, a GaN layer doped with Si).

  The semiconductor layer 22 is provided on the semiconductor layer 16. The semiconductor layer 22 is provided between the semiconductor layers 20. The semiconductor layer 22 is provided under the gate 38 of the transistor 30. The semiconductor layer 22 is, for example, a p-type GaN layer (specifically, a GaN layer doped with Mg).

  The element isolation layer 24 is provided on the semiconductor layer 16. As illustrated in FIG. 1, the element isolation layer 24 is provided around the semiconductor layer 20 in a plan view (as viewed from the Z-axis direction, as viewed from the stacking direction of the semiconductor layers 42 a and 42 b of the light emitting unit 40). Yes. The element isolation layer 24 is, for example, an i-type GaN layer, a silicon oxide layer, a silicon nitride layer, or the like. The element isolation layer 24 electrically isolates the light emitting units 40 adjacent in the X-axis direction.

  As illustrated in FIG. 2, the transistor 30 includes a source region 32, a drain region 34, a channel region 36, and a gate 38. The source region 32 and the drain region 34 are provided in the semiconductor layer 20. The channel region 36 is a region between the source region 32 and the drain region 34. The channel region 36 is provided in the semiconductor layer 22. For example, a capacitance is formed in the channel region 36.

  The gate 38 is provided on the semiconductor layer 22. The gate 38 controls the current flowing through the channel region 36. The gate 38 includes a gate insulating layer 38a provided on the semiconductor layer 22 and a gate electrode 38b provided on the gate insulating layer 38a. The gate insulating layer 38a is, for example, a silicon oxide layer. The material of the gate insulating layer 38a is, for example, copper or aluminum.

  A plurality of transistors 30 are provided. The transistors 30 are provided in an array. That is, the transistors 30 are provided side by side in a predetermined direction. In the example illustrated in FIG. 1, the transistors 30 are provided side by side (in a matrix) in the X-axis direction and the Y-axis direction. The transistors 30 arranged in the X-axis direction have, for example, a common gate insulating layer 38a and a gate electrode 38b. In the illustrated example, the gate electrode 38 b extends from the pad 8 provided on the element isolation layer 24 in the X-axis direction. The plurality of gate electrodes 38b are arranged in the Y-axis direction. As shown in FIG. 2, the transistors 30 adjacent in the Y-axis direction have, for example, a common source region 32.

  The transistor 30 is provided corresponding to the light emitting unit 40. In the present embodiment, the number of transistors 30 and the number of light emitting units 40 are the same, and the transistors 30 are electrically connected to the light emitting units 40. Specifically, the source region 32 or the drain region 34 of the transistor 30 is electrically connected to the semiconductor layer 42 a of the light emitting unit 40. That is, the source region 32 or the drain region 34 is electrically connected to the semiconductor layer 42a even when the transistor 30 is in an OFF state (a state in which no current flows through the channel region 36). In the illustrated example, the drain region 34 is electrically connected to the semiconductor layer 42a. The transistor 30 controls the amount of current injected into the columnar part 42 of the light emitting unit 40. Further, by controlling the transistor 30, the light emission timing can be controlled for each light emitting unit 40. Further, the amount of current injected into the light emitting unit 40 may be controlled by controlling the transistor 30.

  In the present invention, the phrase “the transistor 30 is provided corresponding to the light emitting portion 40” represents that at least one transistor 30 is provided corresponding to the light emitting portion 40. In the present invention, the number of transistors provided corresponding to the light emitting unit 40 is not limited to one, and a plurality of transistors may be provided corresponding to the light emitting unit 40.

  The light emitting unit 40 is provided on the semiconductor layer 20. A plurality of light emitting units 40 are provided. The light emitting units 40 are provided in an array. In other words, the light emitting units 40 are provided side by side in a predetermined direction. In the example illustrated in FIG. 1, the light emitting units 40 are provided side by side (in a matrix) in the X axis direction and the Y axis direction. Here, FIG. 5 is a plan view schematically showing the light emitting unit 40. 6 is a cross-sectional view taken along the line VI-VI of FIG.

  As shown in FIGS. 5 and 6, the light emitting part 40 includes a columnar part 42 and a light propagation layer 44. For convenience, the conductive layer 70 and the insulating layer 60 are not shown in FIG.

  In the present invention, “up” refers to a direction away from the substrate 10 when viewed from the columnar portion 42 in the Z-axis direction (the stacking direction of the semiconductor layer 42a and the light emitting layer 42b of the columnar portion 42). “Down” refers to a direction approaching the substrate 10 when viewed from the columnar portion 42 in the Z-axis direction.

  The columnar part 42 is provided on the semiconductor layer 20. The columnar part 42 has a columnar shape. The columnar part 42 protrudes from the semiconductor layer 20. A plurality of columnar portions 42 are provided. In the example illustrated in FIG. 5, the planar shape (the shape viewed from the Z-axis direction) of the columnar portion 42 is a quadrangle. The diameter of the columnar section 42 (inscribed circle diameter in the case of a polygon) is on the order of nm (less than 1 μm), and specifically 10 nm or more and 500 nm or less. The columnar section 42 is also called, for example, a nanocolumn, nanowire, nanorod, or nanopillar. The size of the columnar part 42 in the Z-axis direction is, for example, not less than 0.1 μm and not more than 5 μm. The plurality of columnar portions 42 are separated from each other. The interval between the adjacent columnar portions 42 is, for example, 1 nm or more and 500 nm or less.

  The planar shape of the columnar portion 42 is not particularly limited, and may be a polygon other than a quadrangle such as a hexagon, a circle, an ellipse, or the like. In the illustrated example, the columnar portion 42 has a constant diameter in the Z-axis direction, but may have a different diameter in the Z-axis direction.

  The plurality of columnar portions 42 are arranged at a predetermined pitch in a predetermined direction in plan view. 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 light emitting layer 42b of the columnar section 42 includes the wavelength λ, and thus can exhibit the effect of a photonic crystal. In the example shown in FIG. 5, the columnar portions 42 are provided side by side (in a matrix) in the X-axis direction and the Y-axis direction.

  As shown in FIG. 6, the columnar section 42 includes a semiconductor layer (first semiconductor layer) 42a, a light emitting layer 42b, and a semiconductor layer (second semiconductor layer) 42c.

  The semiconductor layer 42 a is provided on the semiconductor layer 20. The semiconductor layer 42a is provided between the base 10 and the light emitting layer 42b. The semiconductor layer 42a is, for example, an n-type GaN layer (specifically, a GaN layer doped with Si).

  The light emitting layer 42b is provided on the semiconductor layer 42a. The light emitting layer 42b is provided between the semiconductor layer 42a and the semiconductor layer 42c. The light emitting layer 42b is a layer capable of emitting light when current is injected. The light emitting layer 42b 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 light emitting layer 42b is not particularly limited.

  The semiconductor layer 42c is provided on the light emitting layer 42b. The semiconductor layer 42c is a layer having a conductivity type different from that of the semiconductor layer 42a. The semiconductor layer 42c is, for example, a p-type GaN layer (specifically, a GaN layer doped with Mg). The semiconductor layers 42a and 42c are clad layers having a function of confining light in the light emitting layer 42b (suppressing light leakage from the light emitting layer 42b).

  In the light-emitting device 100, the p-type semiconductor layer 42c, the light-emitting layer 42b not doped with impurities, and the n-type semiconductor layer 42a constitute a pin diode. The semiconductor layers 42a and 42c are layers having a larger band gap than the light emitting layer 42b. In the light emitting device 100, when a forward bias voltage of a pin diode is applied between the conductive layer 70 and the semiconductor layer 20 (current is injected), recombination of electrons and holes occurs in the light emitting layer 42b. This recombination causes light emission. Light generated in the light emitting layer 42b propagates in a direction (plane direction) orthogonal to the Z-axis direction by the semiconductor layers 42a and 42c. The propagated light forms a standing wave due to the effect of the photonic crystal by the columnar section 42, and receives a gain in the light emitting layer 42b to cause laser oscillation. 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 conductive layer 70 side and the substrate 10 side).

  In the light emitting device 100, the refractive indexes and thicknesses of the semiconductor layers 42a and 42c and the light emitting layer 42b are designed so that the intensity of the light propagating in the plane direction is maximized in the light emitting layer 42b in the Z-axis direction. ing.

  Although not shown, a reflective layer may be provided between the base 10 and the semiconductor layer 20 or below the base 10. The reflective layer is, for example, a DBR (Distributed Bragg Reflector) layer. The light generated in the light emitting layer 42b can be reflected by the reflective layer, and the light emitting device 100 can emit light only from the conductive layer 70 side.

  In the illustrated example, an insulating layer 43 is provided on the semiconductor layer 20. The insulating layer 43 is provided between the light propagation layer 44 and the semiconductor layer 20 and between the low refractive index portion 50 and the semiconductor layer 20. The insulating layer 43 functions as a mask for forming the columnar portion 42. The insulating layer 43 may be formed in the same process as the gate insulating layer 38a. Therefore, the insulating layer 43 may have the same material and thickness as the gate insulating layer 38a.

The light propagation layer 44 is provided between adjacent columnar portions 42. The light propagation layer 44 is provided on the insulating layer 43. The light propagation layer 44 is provided so as to surround the columnar portion 42 in plan view. The refractive index of the light propagation layer 44 is lower than the refractive index of the light emitting layer 42b. The light propagation layer 44 is, for example, a GaN layer or a titanium oxide (TiO ₂ ) layer. The GaN layer that is the light propagation layer 44 may be i-type, n-type, or p-type. The light propagation layer 44 can propagate the light generated in the light emitting layer 42b in the planar direction. In the example illustrated in FIG. 5, the planar shape of the light emitting unit 40 is a square.

  In the present invention, when the “specific member (A member)” is composed of a plurality of materials, the “refractive index of the A member” means the average refraction of the plurality of materials constituting the A member. It is a rate.

  As shown in FIG. 6, the low refractive index portion 50 is provided on the side wall 41 of the light emitting portion 40. The low refractive index portion 50 is provided in the planar direction of the light emitting layer 42b. The low refractive index portion 50 is a sidewall provided on the side wall 41 of the light emitting unit 40. In the illustrated example, the side wall 41 is constituted by a light propagation layer 44. For example, as shown in FIG. 5, the side wall 41 includes a first side surface 41a and a second side surface 41b that face each other, and a third side surface 41c and a fourth side surface 41d that are connected to the side surfaces 41a and 41b and face each other. And have.

As shown in FIG. 6, the low refractive index portion 50 is provided on the insulating layer 43. The low refractive index portion 50 is provided so as to surround the light emitting portion 40 in plan view. The refractive index of the low refractive index portion 50 is lower than the refractive index of the light propagation layer 44. The material of the low refractive index portion 50 is, for example, silicon oxide (SiO ₂ ), silicon nitride (SiN), or the like. The low refractive index part 50 is comprised by the single layer, for example.

  The low refractive index portion 50 can reflect the light generated in the light emitting layer 42b. The light generated in the light emitting layer 42b forms a standing wave between the first side surface 41a and the second side surface 41b. Furthermore, the light generated in the light emitting layer 42b forms a standing wave between the third side surface 41c and the fourth side surface 41d.

  As shown in FIG. 2, the insulating layer 60 is provided on the semiconductor layer 20. The insulating layer 60 is provided so as to cover the gate 38 and the surface 56 of the low refractive index portion 50. The insulating layer 60 is, for example, a silicon oxide layer. The insulating layer 60 has a function of protecting the transistor 30 and the light emitting unit 40 from impact or the like.

  The conductive layer 70 is provided on the light emitting unit 40. In the illustrated example, the conductive layer 70 is provided on the columnar portion 42 and the light propagation layer 44. A plurality of conductive layers 70 are provided according to the number of light emitting units 40. The conductive layer 70 is electrically connected to the semiconductor layer 42 c of the columnar part 42. The conductive layer 70 is, for example, an ITO (Indium Tin Oxide) layer. The light generated in the light emitting layer 42b is transmitted through the conductive layer 70 and emitted.

  Although not shown, a contact layer may be provided between the conductive layer 70 and the light emitting unit 40. The contact layer may be in ohmic contact with the conductive layer 70. The contact layer may be a p-type GaN layer.

  As shown in FIG. 3, the wiring 72 is provided on the insulating layer 60. As shown in FIG. 1, the wiring 72 extends from the pad 9 provided on the element isolation layer 24 in the Y-axis direction, branches according to the number of the conductive layers 70, and is connected to the conductive layer 70. . The wiring 72 is electrically connected to the semiconductor layer 42 c through the conductive layer 70. A plurality of wirings 72 are provided. The plurality of wirings 72 are arranged in the X-axis direction. The wiring 72 intersects the gate electrode 38b in plan view. The material of the wiring 72 is, for example, copper, aluminum, ITO or the like. Although not shown, when the material of the wiring 72 is ITO, the wiring 72 may be provided so as to cover the entire surface of the conductive layer 70.

  The first drive circuit 80 and the second drive circuit 82 are provided on the first substrate 12. In the example shown in FIG. 1, the first drive circuit 80 is provided on the −X axis direction side of the second substrate 14 and the second drive circuit 82 is on the −Y axis direction side of the second substrate 14 in plan view. Is provided. The drive circuits 80 and 82 can inject current into the light emitting layer 42b.

  The first drive circuit 80 is electrically connected to the gate electrode 38b. In the illustrated example, the first drive circuit 80 includes a pad 80 a and is electrically connected to the gate electrode 38 b via the wire 2 and the pad 8. Further, the first drive circuit 80 is electrically connected to the semiconductor layer 20. In the illustrated example, the first drive circuit 80 has a pad 80 b and is electrically connected to the semiconductor layer 20 via the wire 3.

  The second drive circuit 82 is electrically connected to the wiring 72. In the illustrated example, the second drive circuit 82 has a pad 82 a and is electrically connected to the wiring 72 through the wire 4 and the pad 9. The material of the wires 2, 3, 4 and the pads 8, 9, 80a, 80b, 82a is not particularly limited as long as it is conductive. The pad 8 is provided integrally with the gate electrode 38b, for example. The pad 9 is provided integrally with the wiring 72, for example. Although not shown, the drive circuits 80 and 82 may be formed on the second substrate 14.

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

  In the light emitting device 100, a plurality of columnar portions 42 that are provided in the substrate 10 and can emit light when current is injected, and a light propagation layer that is provided between adjacent columnar portions 42 and propagates light generated in the columnar portions 42. And a low refractive index portion 50 provided on the side wall 41 of the light emitting portion 40 and having a lower refractive index than the refractive index of the light propagation layer 44. Therefore, in the light emitting device 100, the low refractive index portion 50 can suppress light from leaking from the side wall 41. Thereby, in the light-emitting device 100, the gain loss of the light which arose in the light emitting layer 42b can be suppressed. Therefore, in the light emitting device 100, the light generated in the light emitting layer 42b can obtain a gain efficiently, and laser oscillation with a low threshold current density can be realized.

  In the light emitting device 100, the columnar portion 42 is provided between the first semiconductor layer 42a, the second semiconductor layer 42c having a conductivity type different from that of the first semiconductor layer 42a, and the first semiconductor layer 42a and the second semiconductor layer 42c. And a light emitting layer 42b capable of emitting light by injecting a current. Therefore, in the light emitting device 100, for example, there is a possibility that dislocations generated due to a difference between the lattice constant of the base 10 and the lattice constant of the semiconductor layer 20 exist in a region having a certain height or more of the columnar portion 42. Since it can be reduced, the possibility that dislocations are present in the light emitting layer 42b can be reduced.

  In the light emitting device 100, the refractive index of the light propagation layer 44 is lower than the refractive index of the light emitting layer 42b. Therefore, in the light emitting device 100, the light generated in the light emitting layer 42b easily propagates in the plane direction in the light propagation layer 44.

  In the light emitting device 100, the low refractive index portion 50 is provided so as to surround the light emitting portion 40. Therefore, in the light-emitting device 100, it can suppress more reliably that light leaks. Further, in the light emitting device 100, standing waves can be formed between the first side surface 41 a and the second side surface 41 b of the light emitting unit 40 and between the third side surface 41 c and the fourth side surface 41 d of the light emitting unit 40. . Therefore, the light emitting device 100 can realize laser oscillation with a lower threshold current density.

  The light emitting device 100 includes a transistor 30 provided corresponding to the light emitting unit 40. Therefore, in the light emitting device 100, the light emission timing can be controlled for each light emitting unit 40 by controlling the transistor 30.

  In the light emitting device 100, the light emitting units 40 are provided in an array. Therefore, the light-emitting device 100 can constitute a self-light-emitting imager that can form an image using one light-emitting unit 40 as a pixel.

  In the light emitting device 100, the source region 32 and the drain region 34 are provided in the first semiconductor layer 20. In this manner, in the light emitting device 100, the transistor 30 and the light emitting unit 40 can be formed on the same substrate (on one base body 10). Therefore, the light emitting device 100 can be reduced in size as compared with the case where the transistor 30 and the light emitting unit 40 are provided on separate substrates.

  Although the InGaN-based light emitting layer 42b has been described above, any material system that can emit light when current is injected can be used as the light emitting layer 42b. For example, semiconductor materials such as AlGaN, AlGaAs, InGaAs, InGaAsP, InP, GaP, and AlGaP can be used. The semiconductor layers 20, 22, 42a, and 42c are not limited to the GaN layer, and are made of a material suitable for the material system described above. The semiconductor layers 20, 22, 42a, and 42c are, for example, an InGaN layer, an AlGaN layer, an AlGaAs layer, an InGaAs layer, an InGaAsP layer, an InP layer, a GaP layer, an AlGaP layer, or the like.

  In the light emitting device 100, the plurality of light emitting layers 42b may not be formed of the same semiconductor material system. For example, by changing the semiconductor material system constituting the light emitting layer 42b, the light emitting section 40 that emits red light, the light emitting section 40 that emits green light, and the light emitting section 40 that emits blue light are the same base. 10 may be provided.

  In the above description, the source region 32 and the drain region 34 of the transistor 30 are provided in the semiconductor layer 20. However, in the light emitting device according to the present invention, the transistor corresponding to the light emitting portion is provided in the driver circuit. It may be done. Further, a transistor corresponding to the light emitting unit may be provided on a base other than the base 10.

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. 7-9 is sectional drawing which shows typically the manufacturing process of the light-emitting device 100 which concerns on 1st Embodiment.

  As shown in FIG. 7, the second substrate 14 is bonded to the first substrate 12 using, for example, a bonding member (not shown). Next, the semiconductor layer 16 and the semiconductor layer 20 are epitaxially grown in this order on the second substrate 14. Next, the semiconductor layer 20 is patterned to form a plurality of openings at predetermined positions. Next, the semiconductor layer 22 is epitaxially grown in the opening, and the element isolation layer 24 is epitaxially grown in another opening. Examples of the epitaxial growth method include a MOCVD (Metal Organic Chemical Deposition) method and an MBE (Molecular Beam Epitaxy) method. The patterning is performed by, for example, photolithography and etching.

  As shown in FIG. 8, an insulating layer 43 a is formed on the semiconductor layers 20 and 22 and on the element isolation layer 24. The insulating layer 43a is formed by, for example, film formation by a CVD (Chemical Vapor Deposition) method or a sputtering method, and patterning by photolithography and etching (hereinafter also simply referred to as “patterning”).

  Next, the gate electrode 38b is formed on the insulating layer 43a. The gate electrode 38b is formed by, for example, film formation by sputtering or vacuum deposition and patterning.

  Next, using the insulating layer 43a as a mask, the semiconductor layer 42a, the light emitting layer 42b, and the semiconductor layer 42c are epitaxially grown in this order on the semiconductor layer 20 by, for example, the MOCVD method or the MBE method. By this step, the columnar section 42 can be formed.

  Next, the light propagation layer 44 is formed around the columnar portion 42. The light propagation layer 44 is formed by, for example, an ELO (Epitaxial Lateral Overgrowth) method such as MOCVD method or MBE method. The light emitting unit 40 can be formed by the above steps. Note that the order of the step of forming the light emitting portion 40 and the step of forming the gate insulating layer 38a is not particularly limited.

  As shown in FIG. 9, the low refractive index portion 50 is formed on the side wall 41 of the light emitting portion 40. The low refractive index portion 50 is formed, for example, by forming an insulating layer (not shown) on the entire surface and then etching back the insulating layer. By this step, for example, the insulating layer 43a can be etched, and the insulating layer 43 and the gate insulating layer 38a are formed. As described above, in the method for manufacturing the light emitting device 100, since the insulating layer 43 and the gate insulating layer 38a can be formed by the same process, compared with the case where the insulating layer 43 and the gate insulating layer 38a are formed by separate processes. Thus, the manufacturing process can be shortened.

  As shown in FIG. 2, an insulating layer 60 is formed on the semiconductor layer 20 and the element isolation layer 24 so as to cover the gate 38 and the low refractive index portion 50. The insulating layer 60 is formed by, for example, film formation by spin coating or CVD, and patterning.

  Next, the conductive layer 70 is formed on the light emitting unit 40. The conductive layer 70 is formed by, for example, film formation by sputtering or vacuum vapor deposition, and patterning.

  As shown in FIGS. 1 and 3, the wiring 72 is formed on the insulating layer 60 and the conductive layer 70. The wiring 72 is formed by, for example, film formation by sputtering or vacuum vapor deposition, and patterning.

  As shown in FIG. 1, drive circuits 80 and 82 are mounted on the first substrate 12 using, for example, a bonding member (not shown). Next, electrical connection is performed by the wires 2, 3, and 4.

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

1.3. Modified example of light emitting device 1.3.1. First Modification Next, a light-emitting device according to a first modification of the first embodiment will be described with reference to the drawings. FIG. 10 is a cross-sectional view schematically showing a light emitting device 110 according to a first modification of the first embodiment. In FIG. 10, an X axis, a Y axis, and a Z axis are illustrated as three axes orthogonal to each other.

  Hereinafter, in the light emitting device 110 according to the first modification of the first embodiment, members having the same functions as those of the components of the light emitting device 100 described above are denoted by the same reference numerals, and detailed description thereof is omitted. This is the same in the light emitting device according to the second modification of the first embodiment described below.

  In the light emitting device 100 described above, as illustrated in FIG. 6, the low refractive index portion 50 is configured by, for example, a single layer. On the other hand, in the light emitting device 110, as shown in FIG. 10, the low refractive index portion 50 is composed of a plurality of layers.

The low refractive index portion 50 is a distributed Bragg reflector (DBR) constituted by a high refractive index layer 52 and a low refractive index layer 54 having a refractive index lower than that of the high refractive index layer 52. . The high refractive index layers 52 and the low refractive index layers 54 are alternately stacked in the planar direction of the light emitting layer 42b. The number of pairs of the high refractive index layer 52 and the low refractive index layer 54 is not particularly limited, but is, for example, 2 pairs or more and 50 pairs or less. The high refractive index layer 52 is, for example, a silicon oxide (SiO ₂ ) layer. The low refractive index layer 54 is, for example, a titanium oxide (TiO ₂ ) layer.

  The light emitting device 110 can have the same effect as the light emitting device 100 described above.

  In the light emitting device 110, the low refractive index portion 50 is a distributed Bragg reflector. Therefore, in the light emitting device 200, for example, the reflectance with respect to the light generated in the light emitting layer 42b can be increased as compared with the case where the low refractive index portion 50 is formed of a single layer.

1.3.2. Second Modified Example Next, a light emitting device according to a second modified example of the first embodiment will be described with reference to the drawings. FIG. 11 is a cross-sectional view schematically showing a light emitting device 110 according to a second modification of the first embodiment.

  In the light emitting device 100 described above, one transistor 30 is provided corresponding to the light emitting unit 40 as shown in FIG. On the other hand, in the light emitting device 120, as shown in FIG. 11, a plurality of transistors 30 are provided corresponding to the light emitting unit 40. In the illustrated example, two transistors 30 are provided corresponding to the light emitting unit 40. Although not shown, in the light emitting device 120, the same number of transistors 30 as the columnar part 42 may be provided for each light emitting part 40.

  The light emitting device 120 can have the same effect as the light emitting device 100 described above.

2. Second Embodiment 2.1. Next, a light emitting device according to a second embodiment will be described with reference to the drawings. FIG. 12 is a cross-sectional view schematically showing the light emitting device 200 according to the second embodiment. In FIG. 12 and FIG. 13 to be described later, an X axis, a Y axis, and a Z axis are illustrated as three axes orthogonal to each other.

  Hereinafter, in the light emitting device 200 according to the second embodiment, members having the same functions as the constituent members of the light emitting device 100 described above are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in FIG. 12, the light emitting device 200 is different from the light emitting device 100 described above in that it includes a metal layer 90.

  The metal layer 90 is provided on the surface 56 of the low refractive index portion 50. The metal layer 90 is provided in the planar direction of the light emitting layer 42b. In the illustrated example, the metal layer 90 is provided between the low refractive index portion 50 and the insulating layer 60. The metal layer 90 is provided separately from the semiconductor layer 20. In the illustrated example, an insulating layer 43 is located between the metal layer 90 and the semiconductor layer 20. The insulating layer 43 electrically separates the metal layer 90 and the semiconductor layer 20. The metal layer 90 is, for example, a silver layer, a copper layer, an aluminum layer, or the like.

  The light emitting device 200 can have the same effect as the light emitting device 100 described above.

  The light emitting device 200 includes a metal layer 90 provided on the surface 56 of the low refractive index portion 50. Therefore, in the light emitting device 200, even if the light generated in the light emitting layer 42b is transmitted through the low refractive index portion 50, the light can be reflected on the metal layer 90. Therefore, in the light emitting device 200, it is possible to more reliably prevent light from leaking.

  Here, although not shown in the figure, if the metal layer 90 is provided directly on the side wall 41 of the light emitting unit 40, the metal layer 90 absorbs visible light at a predetermined rate. Providing the metal layer 90 is not preferable. When the metal layer 90 absorbs light, the metal layer 90 generates heat, and the temperature characteristics of the light emitting device may deteriorate. In the light emitting device 200, since the low refractive index portion 50 is provided between the light emitting portion 40 and the metal layer 90, the above problem can be avoided.

  In the light emitting device 200, the metal layer 90 may be provided integrally with the conductive layer 70 as shown in FIG. In this case, a manufacturing process can be shortened compared with the case where the metal layer 90 and the conductive layer 70 are formed in separate processes.

  Although not shown, in the light emitting device 200, the low refractive index portion 50 may be a distributed Bragg reflector, like the light emitting device 110 described above. Since the light emitting device 200 includes the metal layer 90 that reflects light, the number of pairs of the high refractive index layer 52 and the low refractive index layer 54 of the low refractive index portion 50 that is a distributed Bragg reflector can be reduced.

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. The manufacturing method of the light emitting device 200 according to the second embodiment is, for example, the light emitting device according to the first embodiment described above except that the metal layer 90 is formed by film formation by sputtering or vacuum vapor deposition and patterning. This is basically the same as 100 manufacturing methods. Therefore, the detailed description is abbreviate | omitted.

2.3. Next, a light emitting device according to a modified example of the second embodiment will be described with reference to the drawings. FIG. 14 is a plan view schematically showing a light emitting device 210 according to a modification of the second embodiment. FIG. 15 is a cross-sectional view taken along line XV-XV in FIG. 14 schematically showing a light emitting device 210 according to a modification of the second embodiment. In FIG. 14 and FIG. 15, the X axis, the Y axis, and the Z axis are illustrated as three axes orthogonal to each other.

  Hereinafter, in the light emitting device 210 according to the modified example of the second embodiment, members having the same functions as the constituent members of the light emitting devices 100 and 200 described above are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the light emitting device 200 described above, as shown in FIG. 12, the metal layer 90 is provided directly on the surface 56 of the low refractive index portion 50. On the other hand, in the light emitting device 210, as shown in FIG. 15, the metal layer 90 is provided on the surface 56 of the low refractive index portion 50 via the insulating layer 60.

  The metal layer 90 is connected to the wiring 72 as shown in FIG. In the illustrated example, the metal layer 90 is provided integrally with the wiring 72. The metal layer 90 has, for example, a frame shape in plan view. In plan view, the outer edge of the light emitting unit 40 and the outer edge of the conductive layer 70 overlap the metal layer 90.

  The light emitting device 210 can have the same effect as the light emitting device 200 described above.

  In the light emitting device 210, the metal layer 90 is connected to the wiring 72 that is electrically connected to the second semiconductor layer 42c. Therefore, in the light emitting device 210, the resistance to the current injected into the second semiconductor layer 42c can be reduced.

  In the light emitting device 210, the metal layer 90 is provided integrally with the wiring 72. Therefore, in the light emitting device 210, the manufacturing process can be shortened as compared with the case where the metal layer 90 and the wiring 72 are formed in separate processes.

3. Third Embodiment Next, a projector according to a third embodiment will be described with reference to the drawings. FIG. 15 is a diagram schematically illustrating a projector 300 according to the third embodiment.

  The projector 300 includes the light emitting device according to the present invention. Hereinafter, as shown in FIG. 16, a projector 300 including the light emitting device 100 (light emitting devices 100R, 100G, and 100B) will be described.

  The projector 300 includes a housing (not shown), light emitting devices 100R, 100G, and 100B, a cross dichroic prism (color light combining unit) 302, and a projection lens (projection device) 304 provided in the housing. . For the sake of convenience, in FIG. 16, the housing constituting the projector 300 is omitted, and the light emitting devices 100R, 100G, and 100B are simplified.

  The light emitting devices 100R, 100G, and 100B emit red light, green light, and blue light, respectively. The light emitting devices 100R, 100G, and 100B control (modulate) each light emitting unit 40 as image pixels according to image information, for example, directly without using a liquid crystal light valve (light modulation device). An image can be formed.

  Light emitted from the light emitting devices 100R, 100G, and 100B enters the cross dichroic prism 302. The cross dichroic prism 302 combines the light emitted from the light emitting devices 100R, 100G, and 100B and guides it to the projection lens 304. The projection lens 304 enlarges and projects an image formed by the light emitting devices 100R, 100G, and 100B onto a screen (display surface) (not shown).

  Specifically, the cross dichroic prism 302 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. Has been. These dielectric multilayer films combine the three color lights to form light representing a color image. Then, the synthesized light is projected on the screen by the projection lens 304 which is a projection optical system, and an enlarged image is displayed.

  The projector 300 includes the light emitting device 100. Therefore, the projector 300 can directly form an image without using, for example, a liquid crystal light valve (light modulation device). Therefore, in the projector 300, transmission loss in the liquid crystal light valve (a part of light does not pass through the liquid crystal light valve) can be suppressed, and high brightness can be achieved. Further, in the projector 300, the number of parts can be reduced, and the cost can be reduced. Furthermore, since the projector 300 includes the light emitting device 100 that emits laser light, it is possible to project from a remote location as compared with the case of emitting LED (Light Emitting Diode) light.

  For example, the light emitting unit 40 (40R) that emits red light, the light emitting unit 40 (40G) that emits green light, and the light emitting unit 40 (40B) that emits blue light are provided on the same base body 10. When the light emitting device 100 is used, the projector 300 directly enters the projection lens 304 without entering the cross dichroic prism, as shown in FIG. In this case, one light emitting device 100 can display a full-color image, and can be downsized compared to the example shown in FIG.

  Applications of the light-emitting device according to the present invention are not limited to the above-described embodiments, but besides projectors, indoor / outdoor lighting, display backlights, laser printers, scanners, in-vehicle lights, sensing devices using light, communication It can also be used as a light source for equipment and the like.

  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, 3, 4 ... Wire, 8, 9 ... Pad, 10 ... Base | substrate, 12 ... 1st board | substrate, 14 ... 2nd board | substrate, 16, 20, 22 ... Semiconductor layer, 24 ... Element isolation layer, 30 ... Transistor, 32 ... Source region, 34 ... Drain region, 36 ... Channel region, 38 ... Gate, 38a ... Gate insulating layer, 38b ... Gate electrode, 40, 40R, 40G, 40B ... Light emitting part, 41 ... Side wall, 41a ... First side surface, 41b ... 2nd side surface, 41c ... 3rd side surface, 41d ... 4th side surface, 42 ... Columnar part, 42a ... Semiconductor layer, 42b ... Light emitting layer, 42c ... Semiconductor layer, 43, 43a ... Insulating layer, 44 ... Light propagation layer 50 ... Low refractive index portion, 52 ... High refractive index layer, 54 ... Low refractive index layer, 56 ... Surface, 60 ... Insulating layer, 70 ... Conductive layer, 72 ... Wiring, 80 ... First drive circuit, 80a, 80b ... Pad, 82 ... Second drive circuit, 82a Pad, 90 ... metal layer, 100,100R, 100G, 100B, 110,200,210 ... light-emitting device, 300 ... projector 302 ... cross dichroic prism 304 ... projection lens

Claims (10)

A substrate;
A plurality of columnar portions provided on the base body and capable of emitting light by injecting current; and a light emitting unit including a light propagation layer provided between the adjacent columnar portions to propagate light generated in the columnar portions;
A low refractive index portion provided on a side wall of the light emitting portion and having a refractive index lower than a refractive index of the light propagation layer;
A light emitting device. In claim 1,
The columnar part is
A first semiconductor layer;
A second semiconductor layer having a conductivity type different from that of the first semiconductor layer;
A light emitting layer provided between the first semiconductor layer and the second semiconductor layer and capable of emitting light by injecting a current;
A light emitting device. In claim 2,
The light emitting device, wherein a refractive index of the light propagation layer is lower than a refractive index of the light emitting layer. In claim 2 or 3,
A light emitting device including a metal layer provided on a surface of the low refractive index portion. In claim 4,
The first semiconductor layer is provided between the base and the light emitting layer,
The light emitting device, wherein the metal layer is connected to a wiring electrically connected to the second semiconductor layer. In any one of Claims 1 thru | or 5,
The low refractive index portion is a light emitting device provided to surround the light emitting portion. In any one of Claims 1 thru | or 6,
The light emitting device, wherein the low refractive index portion is a distributed Bragg reflector. In any one of Claims 1 thru | or 7,
A light emitting device including a transistor provided corresponding to the light emitting unit. In any one of Claims 1 thru | or 8,
The light emitting unit is a light emitting device provided in an array.   A projector comprising the light emitting device according to claim 1.

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