JP2023025741A - Light-emitting device, projector, and display - Google Patents

Abstract

[Problem] To provide a light emitting device capable of selectively injecting a current into the center of a columnar portion. [Solution] A light emitting device comprising a substrate, a stacked body provided on the substrate and having a columnar portion, and a first electrode and a second electrode for injecting a current into the columnar portion, the columnar portion comprising a first semiconductor layer of a first conductivity type, a second semiconductor layer of a second conductivity type different from the first conductivity type, and a light emitting layer provided between the first semiconductor layer and the second semiconductor layer, a first insulating layer is provided on the sidewall of the first semiconductor layer of the columnar portion, a third electrode is provided on the side of the first insulating layer opposite to the first semiconductor layer, and a depletion layer is formed in the first semiconductor layer due to a potential difference between the third electrode and the first semiconductor layer. [Selected Figure] Figure 1

Description

The present invention relates to light emitting devices, projectors, and displays.

Semiconductor lasers are expected to be high-intensity next-generation light sources. In particular, semiconductor lasers to which nanocolumns are applied are expected to realize high-power light emission with a narrow emission angle due to the photonic crystal effect of the nanocolumns.

For example, in US Pat. No. 5,400,004, a first electrode is formed on an electrically insulating surface of a support, a light-emitting semiconductor nanowire is grown on the first electrode, and a second electrode is provided on the free end of the nanowire. A method of manufacturing a light emitting device is described, comprising: forming a .

Japanese Patent Publication No. 2013-502715

In such light-emitting devices, for example, when growing an InGaN layer as the light-emitting layer of a nanowire, the InGaN layer tends to be preferentially grown in the center of the nanowire. Therefore, it is desirable to selectively inject current into the center of the nanowire.

One aspect of the light-emitting device according to the present invention is
a substrate;
a laminate provided on the substrate and having a columnar portion;
a first electrode and a second electrode for injecting current into the columnar portion;
has
The columnar portion is
a first semiconductor layer of a first conductivity type;
a second semiconductor layer of a second conductivity type different from the first conductivity type;
a light-emitting layer provided between the first semiconductor layer and the second semiconductor layer;
has
A first insulating layer is provided on a side wall of the first semiconductor layer of the columnar portion,
A third electrode is provided on the side of the first insulating layer opposite to the first semiconductor layer,
A depletion layer is formed in the first semiconductor layer due to the potential difference between the third electrode and the first semiconductor layer.

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

One aspect of the display according to the present invention is
It has one mode of the light-emitting device.

BRIEF DESCRIPTION OF THE DRAWINGS Sectional drawing which shows typically the light-emitting device which concerns on this embodiment. 4A to 4C are cross-sectional views schematically showing manufacturing steps of the light-emitting device according to the present embodiment; 4A to 4C are cross-sectional views schematically showing manufacturing steps of the light-emitting device according to the present embodiment; 4A to 4C are cross-sectional views schematically showing manufacturing steps of the light-emitting device according to the present embodiment; 4A to 4C are cross-sectional views schematically showing manufacturing steps of the light-emitting device according to the present embodiment; 4A to 4C are cross-sectional views schematically showing manufacturing steps of the light-emitting device according to the present embodiment; 4A to 4C are cross-sectional views schematically showing manufacturing steps of the light-emitting device according to the present embodiment; 4A to 4C are cross-sectional views schematically showing manufacturing steps of the light-emitting device according to the present embodiment; Sectional drawing which shows typically the light-emitting device which concerns on the 1st modification of this embodiment. Sectional drawing which shows typically the light-emitting device which concerns on the 2nd modification of this embodiment. FIG. 2 is a diagram schematically showing a projector according to the embodiment; FIG. FIG. 2 is a plan view schematically showing the display according to the embodiment; Sectional drawing which shows typically the display which concerns on this embodiment.

Preferred embodiments of the present invention will be described in detail below with reference to the drawings. It should be noted that the embodiments described below do not unduly limit the scope of the invention described in the claims. Moreover, not all the configurations described below are essential constituent elements of the present invention.

1. Light-Emitting Device First, a light-emitting device according to the present 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 this embodiment.

The light emitting device 100 includes, for example, a substrate 10, a laminate 20, an insulating layer 40, a first electrode 50, a second electrode 52, a third electrode 54, and a fourth electrode 56, as shown in FIG. , and an SOG (Spin-on-Glass) layer 60 . The light emitting device 100 is, for example, a semiconductor laser.

The substrate 10 is, for example, a Si substrate, a GaN substrate, a sapphire substrate, a SiC substrate, or the like.

The laminate 20 is provided on the substrate 10 . In the illustrated example, the laminate 20 is provided on the substrate 10 . The laminate 20 has, for example, a buffer layer 22 and a plurality of columnar portions 30 . The columnar portion 30 has a first semiconductor layer 32 , a light emitting layer 34 and a second semiconductor layer 36 .

In this specification, in the stacking direction of the stack 20 (hereinafter also simply referred to as “stacking direction”), when the light emitting layer 34 is used as a reference, the direction from the light emitting layer 34 toward the second semiconductor layer 36 is defined as “up”. , the direction from the light emitting layer 34 to the first semiconductor layer 32 is defined as "down". Moreover, the direction perpendicular to the stacking direction is also referred to as the “in-plane direction”. Also, the “stacking direction of the stack 20 ” is the stacking direction of the first semiconductor layer 32 and the light emitting layer 34 .

A buffer layer 22 is provided on the substrate 10 . The buffer layer 22 is, for example, an n-type GaN layer doped with Si. Although not shown, a mask layer for growing the columnar portion 30 is provided on the buffer layer 22 . The mask layer is, for example, a silicon oxide layer, a titanium layer, a titanium oxide layer, an aluminum oxide layer, or the like.

The columnar portion 30 is provided on the buffer layer 22 . The columnar portion 30 has a columnar shape protruding upward from the buffer layer 22 . In other words, the columnar portion 30 protrudes upward from the substrate 10 through the buffer layer 22 . The columnar part 30 is also called nanocolumn, nanowire, nanorod, or nanopillar, for example. The planar shape of the columnar portion 30 is, for example, a polygon such as a hexagon, or a circle.

The diameter of the columnar portion 30 is, for example, 50 nm or more and 500 nm or less. By setting the diameter of the columnar portion 30 to 500 nm or less, it is possible to obtain the light-emitting layer 34 of high quality crystals and to reduce the strain inherent in the light-emitting layer 34 . Thereby, the light generated in the light emitting layer 34 can be amplified with high efficiency.

The “diameter of the columnar portion” is the diameter when the planar shape of the columnar portion 30 is circular, and is the diameter of the minimum inclusive circle when the planar shape of the columnar portion 30 is not circular. For example, if the planar shape of the columnar part 30 is polygonal, the diameter of the columnar part 30 is the diameter of the smallest circle that includes the polygon. The diameter of the smallest circle that can be included inside.

A plurality of columnar portions 30 are provided. The interval between adjacent columnar portions 30 is, for example, 1 nm or more and 500 nm or less. The plurality of columnar portions 30 are arranged at a predetermined pitch in a predetermined direction when viewed from the stacking direction. The plurality of columnar portions 30 are arranged, for example, in a triangular lattice pattern or a square lattice pattern. The plurality of columnar portions 30 can exhibit the effect of photonic crystals.

The “pitch of the columnar portions” is the distance between the centers of the columnar portions 30 adjacent to each other along a predetermined direction. The “center of the columnar portion” is the center of the circle when the planar shape of the columnar portion 30 is circular, and the center of the minimum containing circle when the planar shape of the columnar portion 30 is not circular. . For example, if the planar shape of the columnar portion 30 is polygonal, the center of the columnar portion 30 is the center of the smallest circle that includes the polygon. It is the center of the smallest enclosing circle.

The first semiconductor layer 32 of the columnar portion 30 is provided on the buffer layer 22 . The first semiconductor layer 32 is provided between the substrate 10 and the light emitting layer 34 . The first semiconductor layer 32 is a first conductivity type semiconductor layer. The first semiconductor layer 32 is, for example, an n-type GaN layer doped with Si.

The light emitting layer 34 of the columnar section 30 is provided on the first semiconductor layer 32 . The light emitting layer 34 is provided between the first semiconductor layer 32 and the second semiconductor layer 36 . The light-emitting layer 34 emits light when current is injected into it. The light emitting layer 34 has, for example, a well layer 34a and a barrier layer 34b. The well layer 34a and the barrier layer 34b are i-type semiconductor layers that are not intentionally doped with impurities. The well layer 34a is, for example, an InGaN layer. The barrier layer 34b is, for example, a GaN layer. The light emitting layer 34 has an MQW (Multiple Quantum Well) structure composed of a well layer 34a and a barrier layer 34b. In the illustrated example, the well layer 34a is separated from the sidewall 31 of the columnar section 30 . The well layer 34 a is provided in the center of the columnar section 30 .

The number of well layers 34a and barrier layers 34b that constitute the light-emitting layer 34 is not particularly limited. For example, only one well layer 34a may be provided, and in this case, the light emitting layer 34 has an SQW (Single Quantum Well) structure.

The second semiconductor layer 36 of the columnar section 30 is provided on the light emitting layer 34 . The second semiconductor layer 36 is provided between the light emitting layer 34 and the second electrode 52 . The second semiconductor layer 36 is a semiconductor layer of a second conductivity type different from the first conductivity type. The second semiconductor layer 36 is, for example, a p-type GaN layer doped with Mg. The first semiconductor layer 32 and the second semiconductor layer 36 are clad layers that have the function of confining light in the light emitting layer 34 .

Although not shown, an OCL (OCL) consisting of an i-type InGaN layer and a GaN layer is provided between the first semiconductor layer 32 and the light emitting layer 34 and between the light emitting layer 34 and the second semiconductor layer 36 at least one of them. Optical Confinement Layer) may be provided. The second semiconductor layer 36 may also have an EBL (Electron Blocking Layer) made of a p-type AlGaN layer.

In the light-emitting device 100, the p-type second semiconductor layer 36, the i-type light-emitting layer 34 intentionally not doped with impurities, and the n-type first semiconductor layer 32 form a pin diode. 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 into the light-emitting layer 34, and electrons and holes recombine in the light-emitting layer 34. happens. This recombination produces light emission. The light generated in the light emitting layer 34 propagates in the in-plane direction through the insulating layer 40 and the SOG layer 60, forms a standing wave due to the photonic crystal effect of the plurality of columnar portions 30, and gains in the light emitting layer 34. Receive laser oscillation. Then, the light emitting device 100 emits the +1st-order diffracted light and the −1st-order diffracted light as laser light in the lamination direction.

Although not shown, a reflective layer may be provided between the substrate 10 and the buffer layer 22 or under the substrate 10 . The reflective layer is, for example, a DBR (Distributed Bragg Reflector) layer. The light generated in the light-emitting 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 insulating layer 40 is provided on the sidewall 31 of the columnar portion 30 . The insulating layer 40 surrounds the columnar portion 30 when viewed from the stacking direction. The insulating layer 40 is, for example, a silicon oxide layer. The insulating layer 40 has, for example, a first insulating layer 42 , a second insulating layer 44 and a third insulating layer 46 .

The first insulating layer 42 is provided on the sidewall 31 of the first semiconductor layer 32 of the columnar portion 30 . The first insulating layer 42 surrounds the columnar portion 30 when viewed from the stacking direction. The thickness of the first insulating layer 42 is, for example, 5 nm or more and 100 nm or less. If the thickness of the first insulating layer 42 is 5 nm or more, leakage current flowing from the third electrode 54 through the first insulating layer 42 to the first semiconductor layer 32 can be suppressed. If the thickness of the first insulating layer 42 is 100 nm or less, the depletion layer 2 can be easily formed in the first semiconductor layer 32 .

The “thickness of the first insulating layer 42” is the size of the first insulating layer 42 in the in-plane direction. This is the same for the thickness of the second insulating layer 44 and the thickness of the third insulating layer 46, which will be described later.

The second insulating layer 44 is provided on the sidewall 31 of the second semiconductor layer 36 of the columnar portion 30 . The second insulating layer 44 surrounds the columnar portion 30 when viewed from the stacking direction. The thickness of the second insulating layer 44 is, for example, the same as that of the first insulating layer 42 .

The third insulating layer 46 is provided on the sidewall 31 of the light emitting layer 34 of the columnar section 30 . The third insulating layer 46 surrounds the columnar portion 30 when viewed from the stacking direction. The thickness of the third insulating layer 46 is, for example, the same as that of the first insulating layer 42 . A third insulating layer 46 is provided between the first insulating layer 42 and the second insulating layer 44 . In the illustrated example, the third insulating layer 46 is provided continuously with the first insulating layer 42 and the second insulating layer 44 . The first insulating layer 42 , the second insulating layer 44 , and the third insulating layer 46 are integrally provided to form the insulating layer 40 .

The first electrode 50 is provided on the buffer layer 22 . The buffer layer 22 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 through the buffer layer 22 . The first electrode 50 is one electrode for injecting current into the light emitting layer 34 . As the first electrode 50, for example, one in which a Cr layer, a Ni layer, and an Au layer are laminated in this order from the buffer layer 22 side is used.

The second electrode 52 is provided on the second semiconductor layer 36 . In the illustrated example, the second electrode 52 is further provided on the insulating layer 40 and on the fourth electrode 56 . The second semiconductor layer 36 may be in ohmic contact with the second electrode 52 . The second electrode 52 is the other electrode for injecting current into the light emitting layer 34 . As the second electrode 52, for example, ITO (Indium Tin Oxide), ZnO, or the like is used.

The third electrode 54 is provided on the opposite side of the first insulating layer 42 to the first semiconductor layer 32 . The first insulating layer 42 is sandwiched between the third electrode 54 and the first semiconductor layer 32 . The third electrode 54 is provided between the first semiconductor layers 32 of the adjacent columnar portions 30 . The third electrode 54 is not in contact with the third insulating layer 46 . The third electrode 54 surrounds the columnar portion 30 when viewed from the stacking direction. The third electrode 54 is electrically connected with the first electrode 50 . In the illustrated example, the third electrode 54 is electrically connected to the first electrode 50 through the buffer layer 22 . The material of the third electrode 54 is polysilicon doped with impurities such as phosphorus (P) and boron (B). The impurity-doped polysilicon may be n-type or p-type.

A depletion layer 2 is formed in the first semiconductor layer 32 due to the potential difference between the third electrode 54 and the first semiconductor layer 32 . When the first semiconductor layer 32 is an n-type semiconductor layer, a negative voltage is applied to the third electrode 54 . The resistivity of the first semiconductor layer 32 is higher than that of the third electrode 54 . Therefore, the potential difference between the third electrode 54 and the first semiconductor layer 32 increases from the buffer layer 22 toward the light emitting layer 34 due to the voltage drop. As a result, the width of the depletion layer 2 increases from the buffer layer 22 toward the light emitting layer 34 . The depletion layer 2 is not provided at the center of the columnar portion 30 when viewed from the stacking direction. The "width of the depletion layer 2" is the size of the depletion layer 2 in the in-plane direction. This is the same for the depletion layer 4, which will be described later.

The fourth electrode 56 is provided on the opposite side of the second insulating layer 44 to the second semiconductor layer 36 . The second insulating layer 44 is sandwiched between the fourth electrode 56 and the second semiconductor layer 36 . The fourth electrode 56 is provided between the second semiconductor layers 36 of the adjacent columnar portions 30 . The fourth electrode 56 surrounds the columnar portion 30 when viewed from the stacking direction. In the illustrated example, the fourth electrode 56 is provided on the SOG layer 60 . The fourth electrode 56 is not in contact with the third insulating layer 46 . The fourth electrode 56 is electrically connected with the second electrode 52 . The material of the fourth electrode 56 is, for example, polysilicon doped with impurities such as phosphorus and boron. The impurity-doped polysilicon may be n-type or p-type.

The material forming the third electrode 54 and the fourth electrode 56 is not particularly limited as long as it is conductive, and may be a metal material such as aluminum or a semiconductor material such as GaN doped with an impurity. may

A depletion layer 4 is formed in the second semiconductor layer 36 due to the potential difference between the fourth electrode 56 and the second semiconductor layer 36 . A positive voltage is applied to the fourth electrode 56 when the second semiconductor layer 36 is a p-type semiconductor layer. The resistivity of the second semiconductor layer 36 is higher than that of the fourth electrode 56 . Therefore, the potential difference between the fourth electrode 56 and the second semiconductor layer 36 increases due to the voltage drop from the second electrode 52 toward the light emitting layer 34 . Thereby, the width of the depletion layer 4 increases from the second electrode 52 toward the light emitting layer 34 . The depletion layer 4 is not provided at the center of the columnar portion 30 when viewed from the stacking direction.

The SOG layer 60 is provided between the third electrode 54 and the fourth electrode 56 . The SOG layer 60 is provided on the side of the third insulating layer 46 opposite to the light emitting layer 34 . The third insulating layer 46 is sandwiched between the SOG layer 60 and the light emitting layer 34 . The SOG layer 60 is provided between the light emitting layers 34 of the adjacent columnar portions 30 . In the illustrated example, the SOG layer 60 is provided on the third electrode 54 . The SOG layer 60 surrounds the columnar portion 30 when viewed from the stacking direction. In the illustrated example, the position of the boundary line between the third electrode 54 and the SOG layer 60 and the position of the boundary line between the first semiconductor layer 32 and the light emitting layer 34 are the same in the stacking direction. In the stacking direction, the position of the boundary line between the fourth electrode 56 and the SOG layer 60 and the position of the boundary line between the second semiconductor layer 36 and the light emitting layer 34 are the same.

Although the InGaN-based light-emitting layer 34 has been described above, various materials that can emit light when a current is injected can be used as the light-emitting layer 34 depending on the wavelength of the emitted light. can. For example, AlGaN-based, AlGaAs-based, InGaAs-based, InGaAsP-based, InP-based, GaP-based, and AlGaP-based semiconductor materials can be used.

Moreover, the light emitting device 100 is not limited to a laser, and may be an LED (Light Emitting Diode).

The light emitting device 100 has, for example, the following features.

In the light emitting device 100 , the first insulating layer 42 is provided on the sidewall 31 of the first semiconductor layer 32 of the columnar portion 30 , and the third electrode 54 is provided on the side of the first insulating layer 42 opposite to the first semiconductor layer 32 . is provided, and the depletion layer 2 is formed in the first semiconductor layer 32 due to the potential difference between the third electrode 54 and the first semiconductor layer 32 . Therefore, in the light-emitting device 100, current can be selectively injected into the center of the columnar portion 30 compared to the case where the depletion layer is not formed in the first semiconductor layer. Thereby, for example, when the well layer 34a is separated from the side wall 31 of the columnar portion 30, the luminous efficiency can be increased. Furthermore, non-radiative recombination due to dangling bonds on the sidewalls 31 of the columnar section 30 can be reduced.

Furthermore, in the light-emitting device 100 , the potential difference between the third electrode 54 and the first semiconductor layer 32 increases from the substrate 10 toward the light-emitting layer 34 due to the voltage drop. Therefore, the width of the depletion layer 2 increases from the buffer layer 22 toward the light emitting layer 34 . As a result, compared to the case where the width of the depletion layer increases from the light emitting layer toward the substrate, current can be selectively injected to the center of the columnar portion 30 .

In the light emitting device 100 , the third electrode 54 is electrically connected to the first electrode 50 . Therefore, in the light-emitting device 100, it is not necessary to separately prepare a power source for applying a voltage to the third electrode 54, so that miniaturization can be achieved.

Although not shown, the third electrode 54 does not have to be electrically connected to the first electrode 50 . For example, a power supply for applying voltage to the third electrode 54 may be separately prepared and a voltage higher than that applied to the first electrode 50 may be applied to the third electrode 54 . Thereby, the width of the depletion layer 2 can be increased compared to the case where the third electrode 54 is electrically connected to the first electrode 50 .

In the light emitting device 100, the third electrode 54 surrounds the columnar portion 30 when viewed from the stacking direction. Therefore, in the light-emitting device 100, current can be selectively injected to the center of the columnar section 30 compared to the case where the third electrode does not surround the columnar section when viewed in the stacking direction.

In the light emitting device 100, the material of the third electrode 54 is polysilicon doped with impurities. Therefore, in the light emitting device 100, the third electrode 54 can be formed more easily than when the third electrode is made of a metal material, for example.

In the light emitting device 100, the second insulating layer 44 is provided on the side wall 31 of the second semiconductor layer 36 of the columnar portion 30, and the fourth electrode 56 is provided on the side of the second insulating layer 44 opposite to the second semiconductor layer 36. is provided, and the depletion layer 4 is formed in the second semiconductor layer 36 due to the potential difference between the fourth electrode 56 and the second semiconductor layer 36 . Therefore, in the light-emitting device 100, current can be selectively injected into the center of the columnar section 30 compared to the case where the depletion layer is not formed in the second semiconductor layer. Furthermore, current can be selectively injected to the center of the columnar portion 30 compared to the case where the depletion layer is formed only in one of the first semiconductor layer and the second semiconductor layer.

In the light emitting device 100 , the fourth electrode 56 is electrically connected to the second electrode 52 . Therefore, in the light-emitting device 100, it is not necessary to separately prepare a power source for applying a voltage to the fourth electrode 56, so that miniaturization can be achieved.

In the light emitting device 100, the fourth electrode 56 surrounds the columnar portion 30 when viewed from the stacking direction. Therefore, in the light-emitting device 100, current can be selectively injected to the center of the columnar section 30 compared to the case where the fourth electrode does not surround the columnar section when viewed in the stacking direction.

In the light emitting device 100, the material of the fourth electrode 56 is polysilicon doped with impurities. Therefore, in the light-emitting device 100, the fourth electrode 56 can be formed more easily than when the fourth electrode is made of a metal material, for example.

2. Method for Manufacturing Light Emitting Device Next, a method for manufacturing the light emitting device 100 according to the present embodiment will be described with reference to the drawings. 2 to 8 are cross-sectional views schematically showing manufacturing steps of the light emitting device 100 according to this embodiment.

As shown in FIG. 2, a buffer layer 22 is epitaxially grown on the substrate 10 . Examples of epitaxial growth methods include MOCVD (Metal Organic Chemical Vapor Deposition) and MBE (Molecular Beam Epitaxy).

Next, a mask layer (not shown) is formed on the buffer layer 22 . The mask layer is formed by film formation and patterning by, for example, an electron beam vapor deposition method or a sputtering method. Patterning is performed, for example, by electron beam lithography and dry etching.

Next, using the mask layer as a mask, the first semiconductor layer 32, the light emitting layer 34, and the second semiconductor layer 36 are epitaxially grown on the buffer layer 22 in this order. Examples of epitaxial growth methods include MOCVD and MBE. Through this process, the laminate 20 having a plurality of columnar portions 30 can be formed. When an InGaN layer is used as the well layer 34a, the well layer 34a is selectively grown in the center of the columnar section 30. As shown in FIG.

As shown in FIG. 3, the insulating layer 40 is formed on the side wall 31 of the columnar portion 30 . The insulating layer 40 is formed by ALD (Atomic Layer Deposition), for example.

As shown in FIG. 4, the columnar portion 30 having the insulating layer 40 formed on the side wall 31 and the first conductive layer 54a covering the buffer layer 22 are formed. The first conductive layer 54a is formed, for example, by forming a polysilicon layer by a CVD (Chemical Vapor Deposition) method and doping the polysilicon layer with impurities.

As shown in FIG. 5, the third electrode 54 is formed by etching back the first conductive layer 54a. Etching back of the first conductive layer 54a is performed by dry etching, for example. In the illustrated example, the first conductive layer 54a is etched back so that the position of the upper surface of the third electrode 54 is the same as the position of the upper surface of the first semiconductor layer 32 in the stacking direction.

As shown in FIG. 6, the SOG layer 60a covering the columnar portion 30 having the insulating layer 40 formed on the side wall 31 and the third electrode 54 is formed. The SOG layer 60a is formed, for example, by spin coating.

As shown in FIG. 7, the SOG layer 60a is etched back to form the SOG layer 60. Then, as shown in FIG. Etching back of the SOG layer 60a is performed, for example, by dry etching. In the illustrated example, the SOG layer 60a is etched back so that the top surface of the SOG layer 60 is aligned with the top surface of the light emitting layer 34 in the stacking direction.

As shown in FIG. 8, the columnar portion 30 having the insulating layer 40 formed on the side wall 31 and the second conductive layer 56a covering the SOG layer 60 are formed. The second conductive layer 56a is formed, for example, by forming a polysilicon layer by the CVD method and doping the polysilicon layer with impurities.

As shown in FIG. 1, the second conductive layer 56a is etched back to form the fourth electrode 56. As shown in FIG. Etching back of the second conductive layer 56a is performed, for example, by dry etching. In the illustrated example, the second conductive layer 56a is etched back so that the position of the upper surface of the fourth electrode 56 is the same as the position of the upper surface of the second semiconductor layer 36 in the stacking direction.

Next, the second electrode 52 is formed on the second semiconductor layer 36 and the fourth electrode 56 . Next, a first electrode 50 is formed on the buffer layer 22 . The first electrode 50 and the second electrode 52 are formed by, for example, sputtering or vacuum deposition. The order of forming the first electrode 50 and forming the second electrode 52 is not particularly limited.

The light emitting device 100 can be manufactured through the above steps.

3. Modification of Light Emitting Device 3.1. First Modification Next, a light emitting device according to a first modification of this embodiment will be described with reference to the drawings. FIG. 9 is a cross-sectional view schematically showing a light emitting device 200 according to a first modified example of this embodiment.

Hereinafter, in the light-emitting device 200 according to the first modified example of the present embodiment, members having the same functions as the constituent members of the above-described light-emitting device 100 according to the present embodiment are denoted by the same reference numerals, and a detailed description thereof will be given. omitted. This is the same for the light-emitting device according to the second modification of this embodiment, which will be described below.

In the light emitting device 100 described above, as shown in FIG. 1, the third electrode 54 was provided. On the other hand, in the light emitting device 200, as shown in FIG. 9, the third electrode 54 is not provided.

In the light emitting device 200 , the SOG layers 60 are provided between the first semiconductor layers 32 of the adjacent columnar portions 30 and between the light emitting layers 34 of the adjacent columnar portions 30 .

In the light emitting device 200 , current can be selectively injected into the center of the columnar section 30 by the depletion layer 4 formed in the second semiconductor layer 36 by the potential difference between the fourth electrode 56 and the second semiconductor layer 36 .

3.2. Second Modification Next, a light emitting device according to a second modification of this embodiment will be described with reference to the drawings. FIG. 10 is a cross-sectional view schematically showing a light emitting device 300 according to a second modified example of this embodiment.

In the light emitting device 100 described above, as shown in FIG. 1, the fourth electrode 56 was provided. In contrast, in the light emitting device 300, as shown in FIG. 10, the fourth electrode 56 is not provided.

In the illustrated example, the SOG layer 60 is not provided in the light emitting device 300, for example. Since the SOG layer 60 is not provided in the light emitting device 300, the manufacturing process can be shortened.

In the light emitting device 300 , current can be selectively injected into the center of the columnar section 30 by the depletion layer 2 formed in the first semiconductor layer 32 by the potential difference between the third electrode 54 and the first semiconductor layer 32 .

Although not shown, SOG layers 60 may be provided between the light emitting layers 34 of the adjacent columnar portions 30 and between the second semiconductor layers 36 of the adjacent columnar portions 30 . By providing the SOG layer 60, the flatness of the second electrode 52 can be improved.

Although not shown, the SOG layer 60 is provided between the light emitting layers 34 of the adjacent columnar portions 30, and the SOG layer 60 is not provided between the second semiconductor layers 36 of the adjacent columnar portions 30. Voids may be formed. This can increase the difference between the in-plane average refractive index in the portion where the light-emitting layer 34 is provided and the in-plane average refractive index in the portion where the second semiconductor layer 36 is provided.

4. Projector Next, a projector according to the present embodiment will be described with reference to the drawings. FIG. 11 is a diagram schematically showing a projector 800 according to this embodiment.

The projector 800 has, for example, the light emitting device 100 as a light source.

The projector 800 has a housing (not shown), and a red light source 100R, a green light source 100G, and a blue light source 100B that emit red light, green light, and blue light, respectively, provided in the housing. For convenience, red light source 100R, green light source 100G, and blue light source 100B are simplified in FIG.

The projector 800 further includes a first optical element 802R, a second optical element 802G, a third optical element 802B, a first optical modulator 804R, and a second optical modulator 804G, which are provided in the housing. , a third light modulating device 804B and a projection device 808 . The first light modulating device 804R, the second light modulating device 804G, and the third light modulating device 804B are, for example, transmissive liquid crystal light valves. Projection device 808 is, for example, a projection lens.

Light emitted from the red light source 100R enters the first optical element 802R. Light emitted from the red light source 100R is collected by the first optical element 802R. Note that the first optical element 802R may have a function other than condensing. The same applies to a second optical element 802G and a third optical element 802B, which will be described later.

The light collected by the first optical element 802R enters the first optical modulator 804R. The first light modulator 804R modulates incident light according to image information. The projection device 808 then magnifies the image formed by the first light modulation device 804R and projects it onto the screen 810 .

Light emitted from the green light source 100G enters the second optical element 802G. Light emitted from the green light source 100G is collected by the second optical element 802G.

The light collected by the second optical element 802G enters the second optical modulator 804G. The second light modulator 804G modulates incident light according to image information. Then, the projection device 808 magnifies the image formed by the second light modulation device 804G and projects it onto the screen 810 .

Light emitted from the blue light source 100B enters the third optical element 802B. Light emitted from the blue light source 100B is collected by the third optical element 802B.

The light collected by the third optical element 802B is incident on the third optical modulator 804B. The third light modulator 804B modulates incident light according to image information. The projection device 808 then magnifies the image formed by the third light modulation device 804B and projects it onto the screen 810 .

The projector 800 can also have a cross dichroic prism 806 that synthesizes the light emitted from the first light modulator 804R, the second light modulator 804G, and the third light modulator 804B and guides it to the projection device 808. .

The three color lights modulated by the first light modulator 804R, the second light modulator 804G, and the third light modulator 804B are incident on the cross dichroic prism 806. FIG. The cross dichroic prism 806 is formed by pasting four rectangular prisms together, and a dielectric multilayer film that reflects red light and a dielectric multilayer film that reflects blue light are arranged on the inner surface thereof. These dielectric multilayer films synthesize three color lights to form light representing a color image. The combined light is projected onto the screen 810 by the projection device 808 to display an enlarged image.

Note that the red light source 100R, the green light source 100G, and the blue light source 100B control the light emitting device 100 as pixels of an image according to image information, so that the first light modulation device 804R, the second light modulation device 804G, and the second light modulation device 804G are controlled. An image may be formed directly without using the three-light modulator 804B. Then, the projection device 808 may enlarge the images formed by the red light source 100R, the green light source 100G, and the blue light source 100B and project them onto the screen 810 .

Also, in the above example, a transmissive liquid crystal light valve is used as the light modulation device, but a light valve other than liquid crystal may be used, or a reflective light valve may be used. Examples of such light valves include reflective liquid crystal light valves and digital micro mirror devices. Also, the configuration of the projection device is appropriately changed according to the type of light valve used.

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

5. Display Next, a display according to the present embodiment will be described with reference to the drawings. FIG. 12 is a plan view schematically showing the display 900 according to this embodiment. FIG. 13 is a cross-sectional view schematically showing a display 900 according to this embodiment. For convenience, FIG. 12 shows the X-axis and the Y-axis as two axes orthogonal to each other.

The display 900 has, for example, the light emitting device 100 as a light source.

A display 900 is a display device that displays an image. Images include those that display only character information. The display 900 is a self-luminous display. The display 900 has a circuit board 910, a lens array 920, and a heat sink 930, as shown in FIGS.

A drive circuit for driving the light emitting device 100 is mounted on the circuit board 910 . The drive circuit is a circuit including, for example, CMOS (Complementary Metal Oxide Semiconductor). The driving circuit drives the light emitting device 100 based on, for example, input image information. Although not shown, a translucent substrate is arranged on the circuit board 910 to protect the circuit board 910 .

The circuit board 910 has a display area 912 , a data line driving circuit 914 , a scanning line driving circuit 916 and a control circuit 918 .

The display area 912 is composed of a plurality of pixels P. As shown in FIG. The pixels P are arranged along the X and Y axes in the illustrated example.

Although not shown, the circuit board 910 is provided with a plurality of scanning lines and a plurality of data lines. For example, the scan lines run along the X-axis and the data lines run along the Y-axis. The scanning lines are connected to a scanning line driver circuit 916 . The data lines are connected to the data line driving circuit 914 . Pixels P are provided corresponding to intersections of scanning lines and data lines.

One pixel P has, for example, one light emitting device 100, one lens 922, and a pixel circuit (not shown). The pixel circuit includes a switching transistor that functions as a switch for the pixel P, the gate of the switching transistor being connected to the scanning line and one of the source or drain being connected to the data line.

The data line driving circuit 914 and the scanning line driving circuit 916 are circuits that control the driving of the light emitting device 100 forming the pixel P. FIG. A control circuit 918 controls the display of images.

Image data is supplied to the control circuit 918 from a higher-level circuit. The control circuit 918 supplies various signals based on the image data to the data line driving circuit 914 and scanning line driving circuit 916 .

When a scanning line is selected by the scanning line driving circuit 916 activating the scanning signal, the switching transistor of the selected pixel P is turned on. At this time, the data line driving circuit 914 supplies a data signal from the data line to the selected pixel P, so that the light emitting device 100 of the selected pixel P emits light according to the data signal.

Lens array 920 has a plurality of lenses 922 . For example, one lens 922 is provided for one light emitting device 100 . Light emitted from the light emitting device 100 enters one lens 922 .

A heat sink 930 is in contact with the circuit board 910 . The material of the heat sink 930 is, for example, metal such as copper or aluminum. The heat sink 930 dissipates heat generated by the light emitting device 100 .

The light-emitting device according to the above-described embodiments can be used for applications other than projectors and displays. Applications other than projectors and displays include, for example, indoor and outdoor lighting, laser printers, scanners, vehicle lights, sensing devices that use light, and light sources for communication devices.

The light-emitting device according to the above-described embodiments can be used for applications other than projectors and displays. Applications other than projectors and displays include, for example, indoor and outdoor lighting, laser printers, scanners, vehicle lights, sensing devices that use light, and light sources for communication devices. Moreover, the light emitting device according to the above-described embodiments can be used as a display device for a head mounted display.

The above-described embodiments and modifications are examples, and the present invention is not limited to these. For example, it is also possible to appropriately combine each embodiment and each modification.

The present invention includes configurations that are substantially the same as the configurations described in the embodiments, for example, configurations that have the same function, method and result, or configurations that have the same purpose and effect. Moreover, the present invention includes configurations obtained by replacing non-essential portions of the configurations described in the embodiments. In addition, the present invention includes a configuration that achieves the same effects or achieves the same purpose as the configurations described in the embodiments. In addition, the present invention includes configurations obtained by adding known techniques to the configurations described in the embodiments.

The following content is derived from the embodiment and modifications described above.

One aspect of the light-emitting device is
a substrate;
a laminate provided on the substrate and having a columnar portion;
a first electrode and a second electrode for injecting current into the columnar portion;
has
The columnar portion is
a first semiconductor layer of a first conductivity type;
a second semiconductor layer of a second conductivity type different from the first conductivity type;
a light-emitting layer provided between the first semiconductor layer and the second semiconductor layer;
has
A first insulating layer is provided on a side wall of the first semiconductor layer of the columnar portion,
A third electrode is provided on the side of the first insulating layer opposite to the first semiconductor layer,
A depletion layer is formed in the first semiconductor layer due to the potential difference between the third electrode and the first semiconductor layer.

According to this light emitting device, a current can be selectively injected into the center of the columnar portion.

In one aspect of the light-emitting device,
The third electrode may be electrically connected to the first electrode.

According to this light emitting device, it is not necessary to separately prepare a power source for applying a voltage to the third electrode, so it is possible to reduce the size of the device.

In one aspect of the light-emitting device,
The third electrode may surround the columnar portion when viewed from the stacking direction of the laminate.

According to this light emitting device, current can be selectively injected into the center of the columnar portion.

In one aspect of the light-emitting device,
A material of the third electrode may be polysilicon doped with impurities.

According to this light emitting device, the third electrode can be easily formed.

In one aspect of the light-emitting device,
A second insulating layer is provided on a side wall of the second semiconductor layer of the columnar portion,
A fourth electrode is provided on the side of the second insulating layer opposite to the second semiconductor layer,
A depletion layer may be formed in the second semiconductor layer due to a potential difference between the fourth electrode and the second semiconductor layer.

According to this light emitting device, a current can be selectively injected into the center of the columnar portion.

In one aspect of the light-emitting device,
The fourth electrode may be electrically connected to the second electrode.

According to this light emitting device, it is not necessary to separately prepare a power source for applying a voltage to the fourth electrode, so that the size can be reduced.

In one aspect of the light-emitting device,
The fourth electrode may surround the columnar portion when viewed from the stacking direction of the laminate.

According to this light emitting device, current can be selectively injected into the center of the columnar portion.

In one aspect of the light-emitting device,
A material of the fourth electrode may be polysilicon doped with impurities.

According to this light emitting device, the fourth electrode can be easily formed.

One aspect of the projector is
It has one mode of the light-emitting device.

One aspect of the display is
It has one mode of the light-emitting device.

Reference Signs List 2, 4 Depletion layer 10 Substrate 20 Stacked body 22 Buffer layer 30 Columnar portion 31 Side wall 32 First semiconductor layer 34 Light emitting layer 36 Second semiconductor layer 40 Insulating layer 42 First insulating layer 44 Second insulating layer 46 Third insulating layer 50 First electrode 52 Second electrode 54 Third electrode 54a First conductive layer 56... Fourth electrode 56a... Second conductive layer 60, 60a... SOG layer 100, 200, 300... Light emitting device 800... Projector 802R... First optical element 802G... Second optical element 802B... Second 3 optical elements, 804R...first optical modulator, 804G...second optical modulator, 804B...third optical modulator, 806...cross dichroic prism, 808...projector, 810...screen, 900...display, 910...circuit Substrate 912 Display area 914 Data line driving circuit 916 Scanning line driving circuit 918 Control circuit 920 Lens array 922 Lens 930 Heat sink

Claims (10)

a substrate;
a laminate provided on the substrate and having a columnar portion;
a first electrode and a second electrode for injecting current into the columnar portion;
has
The columnar portion is
a first semiconductor layer of a first conductivity type;
a second semiconductor layer of a second conductivity type different from the first conductivity type;
a light-emitting layer provided between the first semiconductor layer and the second semiconductor layer;
has
A first insulating layer is provided on a side wall of the first semiconductor layer of the columnar portion,
A third electrode is provided on the side of the first insulating layer opposite to the first semiconductor layer,
A light-emitting device, wherein a depletion layer is formed in the first semiconductor layer due to a potential difference between the third electrode and the first semiconductor layer. In claim 1,
The light-emitting device, wherein the third electrode is electrically connected to the first electrode. In claim 1 or 2,
The light-emitting device, wherein the third electrode surrounds the columnar portion when viewed from the lamination direction of the laminate. In any one of claims 1 to 3,
The light-emitting device, wherein the material of the third electrode is polysilicon doped with an impurity. In any one of claims 1 to 4,
A second insulating layer is provided on a side wall of the second semiconductor layer of the columnar portion,
A fourth electrode is provided on the side of the second insulating layer opposite to the second semiconductor layer,
A light-emitting device, wherein a depletion layer is formed in the second semiconductor layer due to a potential difference between the fourth electrode and the second semiconductor layer. In claim 5,
The light-emitting device, wherein the fourth electrode is electrically connected to the second electrode. In claim 5 or 6,
The light-emitting device, wherein the fourth electrode surrounds the columnar portion when viewed from the lamination direction of the laminate. In any one of claims 5 to 7,
The light-emitting device, wherein the material of the fourth electrode is impurity-doped polysilicon. A projector comprising the light emitting device according to claim 1 . A display comprising a light emitting device according to any one of claims 1 to 8.

Images