KR100599055B1 - Semiconductor light emitting device - Google Patents

Abstract

The present invention provides a semiconductor light emitting device having a plurality of semiconductor layers having an active layer that generates light through recombination of electrons and holes, characterized in that it comprises a trench formed with a projection for scattering on the bottom surface; It relates to a semiconductor light emitting device.

Light emitting element, nitride semiconductor, external quantum efficiency, light emitting diode, projection

Description

Semiconductor Light Emitting Device {SEMICONDUCTOR LIGHT EMITTING DEVICE}

1 is a cross-sectional view and a plan view showing an example of a conventional semiconductor light emitting device;

2 is a plan view of the semiconductor light emitting device of FIG. 1;

3 is a cross-sectional view showing another example of a conventional semiconductor light emitting device;

4 is a cross-sectional view showing still another example of a conventional semiconductor light emitting device;

5 is a cross-sectional view showing still another example of a conventional semiconductor light emitting device;

6 is a schematic view of a semiconductor light emitting device in which an arc is formed;

7 is a schematic view of a semiconductor light emitting element having protrusions formed on the bottom surface of an arc;

8 is a schematic view of a semiconductor light emitting device in which an arc is formed by obliquely removing sidewalls of an arc;

9 is a schematic view of a semiconductor light emitting device in which sidewalls of an arc are removed obliquely and protrusions are formed on a bottom surface thereof;

10 is a schematic diagram of a semiconductor light emitting element in which a plurality of arcs are formed;

11 is a plan view of a semiconductor light emitting device according to the present invention;

12 is a cross-sectional view along the line AA ′ of FIG. 11;

13 is a plan view of another semiconductor light emitting device according to the present invention;

14 is a cross-sectional view along the line BB ′ of FIG. 13;

15 is a plan view of another semiconductor light emitting device according to the present invention;

FIG. 16 is a cross-sectional view along the line CC ′ in FIG. 15.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor light emitting device, and more particularly, to a semiconductor light emitting device having a trench in which a projection for scattering is formed on a bottom surface in order to increase external quantum efficiency. Here, the semiconductor light emitting device refers to a semiconductor light emitting device that emits light by recombination of electrons and holes, and typically, a group III nitride semiconductor light emitting device.

1 and 2 are cross-sectional and plan views illustrating an example of a conventional semiconductor light emitting device, and a group III nitride semiconductor light emitting device is exemplified, and the semiconductor light emitting device is epitaxially grown on the substrate 1 and the substrate 1. (2), an n-type nitride semiconductor layer 3 epitaxially grown on the buffer layer 2, an active layer 4 epitaxially grown on the n-type nitride semiconductor layer 3, and a p-type nitride semiconductor epitaxially grown on the active layer 4 Layer 5, p-side electrode 6 formed on p-type nitride semiconductor layer 5, p-side bonding pad 7 formed on p-side electrode 6, p-type nitride semiconductor layer 5 and active layer (4) includes an n-side electrode 8 formed on the n-type nitride semiconductor layer 31 exposed by mesa etching. The semiconductor light emitting device generates light in the active layer 4 through recombination of electrons and holes, and the generated light exits outside the semiconductor light emitting device to function as a light emitting device.

Although as much light as possible from the light generated in the active layer 4 comes out of the light emitting device to increase the efficiency (external quantum efficiency) of the light emitting device, the difference between the material constituting the light emitting device and the outside (air) and refractive index As a result, some of the generated light is trapped inside the light emitting device, and thus cannot be escaped by heat.

US Patent No. 3,739,217, Japanese Patent Application Laid-Open No. H06-291368, and US Patent No. 5,429,954 are intended to solve this problem. As shown in FIG. 3, a rough surface 1000 is formed on a light emitting device. In addition, the structure which increases the probability that the light generated in the active layer 4 can escape to the outside of the light emitting device is proposed.

In addition, as the semiconductor light emitting device becomes larger in recent years, the problem of how to radiate heat generated inside the light emitting device to the outside of the light emitting device has emerged.

Fig. 4 is a cross-sectional view showing still another example of a conventional semiconductor light emitting device, wherein a portion of the p-type nitride semiconductor layer 5, the active layer 4, and the n-type nitride semiconductor layer 3 are removed to form a plurality of arcs (9). A group III nitride semiconductor light emitting device having a trench formed therein is provided, and the external quantum efficiency of the device is increased by extracting light 91 through the arc 9. Japanese Patent Application Laid-Open Nos. 2002-026386 and 2002-164574 disclose a technique in which such a method is applied to a group III nitride semiconductor light emitting device, and Japanese Patent Laid-Open No. S50-105286 discloses a technology for a semiconductor light emitting device having a pn junction structure. A technique employing a call is disclosed.

FIG. 5 is a view showing another example of a conventional semiconductor light emitting device, wherein an electric field or an electric field 2000 is formed between the p-side bonding pad 7 and the n-side electrode 8, and the electric field 2000 is a device. A technique is disclosed in which an arc 9 (Trend for Current Blocking) is formed in the center to prevent it from being driven to the center of the device and to prevent current flow in the center to form the electric field 2000 as the entire device (US Patent No. 6,781,147). .

SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to provide a semiconductor light emitting device in which the external quantum efficiency of the semiconductor light emitting device to which the arc is applied is further improved.

In addition, an object of the present invention is to provide a semiconductor light emitting device in which a structure for improving the external quantum efficiency is formed during the device process without further processing.

In addition, an object of the present invention is to provide a semiconductor light emitting device that can efficiently suppress the generation of heat generated inside the light emitting device.

In addition, an object of the present invention is to provide a semiconductor light emitting device which increases the external quantum efficiency through the formation of an arc and minimizes the disturbance of current flow by the formed arc.

To this end, the present invention is a semiconductor light emitting device having a plurality of semiconductor layers having an active layer for generating light through recombination of electrons and holes, the first conductive layer having a first conductivity having a plurality of semiconductor layers located below the active layer A semiconductor light emitting device, comprising: a second semiconductor layer positioned over a semiconductor layer and an active layer and having a second conductivity different from the first conductivity, wherein the plurality of semiconductor layers are formed by removing at least a second semiconductor layer and an active layer; (Trench) is provided, the bottom surface of the arc provides a semiconductor light emitting device, characterized in that the projection for scattering the light generated in the active layer is formed. The present invention improves the emission of light to the outside of the device by providing an arc, and can also emit a larger amount of light to the outside of the device by forming projections on the bottom surface of the arc, that is, the removed light emitting region.

The present invention also provides a semiconductor light emitting device, characterized in that the side of the arc is an inclined surface. Since the side of the arc is formed of an inclined surface, the area in which light can be emitted to the outside is expanded, which can lead to an improvement in external quantum efficiency.

In addition, the present invention is characterized in that the first semiconductor layer and the second semiconductor layer is _composed of Al _x Ga _y In _{1 -x- y} N (0≤x≤1, 0≤y≤1, 0≤x + y≤1) A semiconductor light emitting device is provided. This means that the present invention can be applied to a group III nitride semiconductor light emitting device.

In addition, the present invention provides a semiconductor light emitting device, characterized in that the arc is located in the center of the semiconductor light emitting device includes a center arc for suppressing the heat generation of the semiconductor light emitting device. In recent years, the semiconductor light emitting device has a tendency to have a large area, and the tendency of a large area has a problem of suppressing heat generation or heat dissipation of the device, and the provision of such a center arc is a preferred embodiment of the present invention for a large area of the device. have.

In another aspect, the present invention provides a semiconductor light emitting device, characterized in that the substrate is an insulating or conductive substrate. Sapphire substrates are often used as the insulating substrate, and GaAs substrates, SiC substrates, and the like are used as the conductive substrates. Any substrate may be used as long as the semiconductor layer can be grown.

In addition, the present invention provides a semiconductor light emitting device, characterized in that the formation of the arc, the formation of the projections, and the removal of the plurality of semiconductor layers for forming the first electrode are performed using one mask pattern. Removal of the plurality of semiconductor layers may be performed through dry etching, wet etching, and the like, and the present invention may be performed by forming arcs and protrusions together in a process for forming electrodes (this is a pattern of a mask used for forming electrodes of the prior art). It can be made easily by removing the plurality of semiconductor layers by adding a pattern for the formation of the arc and the projections), it is possible to provide a semiconductor light emitting device having an improved external quantum efficiency without additional processes.

In addition, the present invention provides a semiconductor light emitting device, characterized in that the arc is formed along the electric field direction so as not to disturb the current flow. This feature distinguishes the arc of the present invention from an arc formed to interfere with the conventional current flow, and by forming the arc along the electric field direction, it is possible to increase the external quantum efficiency without disturbing the current flow.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

FIG. 6 is a schematic view of a semiconductor light emitting device in which an arc is formed, and a portion of the p-type semiconductor layer 501, the active layer 401, and the n-type semiconductor layer 301 is removed to form an arc 10. This arc 10 shows that most of the light A, B, and C generated in the active layer 401 have a light incident angle larger than the exit angle θ _c . The arc 10 will vary depending on the size of the device, and the area can usually have a size of 1um ² to 1mm ² .

FIG. 7 is a schematic view of a semiconductor light emitting element having protrusions formed on the bottom surface of the arc, and it is possible to extract light A, B, and C generated in the active layer 402 more efficiently. In this case, the protrusion 20 may have a horn shape or a hemisphere shape, and a cross section of the bottom thereof may have various shapes such as a circle, a triangle, a rectangle, and a hexagon. The bottom area of the protrusion 20 may have a size of 1 nm ² to 10 um ² , and the height may have a size of 1 nm to 10 um.

8 is a schematic view of a semiconductor light emitting device in which an arc is formed by obliquely removing sidewalls of an arc, and the sidewalls are formed as an inclined surface 30 to efficiently extract light A, B, and C generated in the active layer 403. Can be. The inclination angle θ of the inclined surface has an angle smaller than 90 °, and preferably has an inclination angle of 45 ° to 55 °.

9 is a schematic view of a semiconductor light emitting device in which the sidewalls of the arc are obliquely removed and protrusions are formed on the bottom surface. External quantum efficiency can be improved.

FIG. 10 is a schematic view of a semiconductor light emitting element in which a plurality of arcs are formed, and when the arcs 11 are plural and the spacing of the arcs 11 is narrow, the external quantum efficiency may be further increased.

11 is a plan view of a semiconductor light emitting device according to the present invention, in which a transmissive electrode 600 is formed on a p-type semiconductor layer 506, a p-side bonding pad 700 is formed on the transmissive electrode, and an n-type semiconductor is exposed. The n-side electrode 800 is formed on the layer 900.

An arc 12 is located between the p-side bonding pad 700 and the n-side electrode 800, the arc 12 is formed in a direction that does not disturb the flow of current, preferably the same as the direction of the electric field Is formed in the direction. The direction of the electric field may be changed according to the formation positions of the p-side bonding pad 700 and the n-side electrode 800, and the arc 12 may be formed in accordance with the arrangement of the electrodes.

FIG. 12 is a cross-sectional view along the AA ′ line of FIG. 11, in which the p-type semiconductor layer 506, the active layer 406, and the n-type semiconductor layer 306 are etched and exposed, as well as the bottom surface of the arc 12. The protrusion 22 is formed.

Typical semiconductor light emitting devices consume power between 60 and 100 mW. In this case, the drive current is about 20 mA and the current density of the device has a value of about 50 A / cm ² . Increasing the number of N) increases the current density of the device. Since excessive increase in current density is undesirable for the operation of the device, it is preferable to design the current density to increase in the range of 50% or less in forming the arc 12.

FIG. 13 is a plan view of another semiconductor light emitting device according to the present invention, which has an electrode structure different from that of FIG. 11, and includes a plurality of p-side bonding pads 701 and a branch connecting them to the transmissive electrode 601. An electrode 710 is formed and a plurality of n-side electrodes 801 and branch electrodes 810 connecting them are formed on the exposed n-type semiconductor layer 901. The arc 13 is formed between these electrodes in the direction which does not disturb the flow of an electric current.

In addition, a center arc 15 is formed at the center of the device, and the center arc 15 is to increase the luminous efficiency of the device by suppressing heat generation by removing the center where heat is concentrated. Depends on 10um ² It is desirable to have an area of about 1 mm ² . If the area of 10um ² or less, the life of the device can not be removed efficiently because the heat generated from the device can be shortened, and if the area of 1mm ² or more, the light emitting area is reduced and the light emitting efficiency of the device can be lowered.

FIG. 14 is a cross-sectional view taken along the line BB ′ of FIG. 13, and not only the bottom surface of the arc 13 but also a region where the p-type semiconductor layer 507, the active layer 407, and the n-type semiconductor layer 307 are etched and exposed. The protrusion 23 is formed.

In the case of the semiconductor light emitting device of FIG. 13, like the semiconductor light emitting device of FIG. 11, the arc 13 is preferably designed such that the current density increases in the range of 50% or less.

15 is a plan view of another semiconductor light emitting device according to the present invention, in which an arc 14 of the present invention is applied to a conductive substrate, and since the n-side electrode is located on the lower surface of the substrate, the p-type semiconductor layer 508 Only the light transmitting electrode 602, the p-side bonding pad 702, and the branch electrode 720 extending therefrom are formed.

FIG. 16 is a cross-sectional view taken along line CC ′ of FIG. 15, in which an n-side electrode 802 is formed on a bottom surface of a substrate 108, and a buffer layer 208, an n-type semiconductor layer 308, The active layer 408 and the p-type semiconductor layer 508 are formed, and the transmissive electrode 602 and the p-side electrode 720 are formed thereon, the p-type semiconductor layer 508, the active layer 408, The n-type semiconductor layer 308 is etched to form an arc 14, and the protrusions 24 are formed on the bottom surface of the arc 14.

Also in the case of the semiconductor light emitting device of FIG. 15, it is preferable that the arc 14 is designed such that the current density increases in the range of 50% or less, similarly to the semiconductor light emitting device of FIG.

According to the present invention, the external quantum efficiency of the semiconductor light emitting device can be further improved by providing an arc having protrusions on the bottom surface.

According to the present invention, the external quantum efficiency of the semiconductor light emitting device can be improved without further processing by performing the process of forming the arc having the protrusion formed on the bottom surface together with the process for forming the electrode.

In addition, according to the present invention, the heat generation of the semiconductor light emitting device can be efficiently suppressed by removing a part of the light emitting region of the device and further removing the central portion of the device.

In addition, according to the present invention, while increasing the external quantum efficiency, it is possible to minimize the disturbance of the current flow by the formed arc.

Claims (22)

A semiconductor light emitting device having a plurality of semiconductor layers including an active layer that generates light through recombination of electrons and holes, wherein the plurality of semiconductor layers are formed on top of an active layer and a first semiconductor layer having a first conductivity located below the active layer. A semiconductor light emitting device comprising: a second semiconductor layer positioned and having a second conductivity different from the first conductivity; The plurality of semiconductor layers are provided with a trench formed by removing at least a second semiconductor layer and an active layer. The bottom surface of the arc is a semiconductor light emitting device, characterized in that the projection for scattering the light generated in the active layer is formed. The semiconductor light emitting device of claim 1, wherein a side of the arc is an inclined surface. The method of claim 1, wherein the first semiconductor layer and second semiconductor layer is made of _{Al x Ga y In 1 -x- y} N (0≤x≤1, 0≤y≤1, 0≤x + y≤1) A semiconductor light emitting device, characterized in that. The semiconductor light emitting device of claim 1, wherein the arc comprises a center arc positioned at a central portion of the semiconductor light emitting device to suppress heat generation of the semiconductor light emitting device. The method of claim 4, wherein the center arc is 10um ² ~ 1 mm ² The semiconductor light emitting device having an area of. The semiconductor light emitting device according to claim 1, wherein the plurality of semiconductor layers are formed on a substrate. 7. The semiconductor light emitting device of claim 6, wherein the substrate is a conductive substrate. 7. The semiconductor light emitting device of claim 6, wherein the substrate is a sapphire substrate. The semiconductor light emitting device of claim 1, wherein the semiconductor light emitting device comprises a first electrode electrically connected to the first semiconductor layer and a second electrode electrically connected to the second semiconductor layer. The semiconductor light emitting device of claim 9, wherein the second electrode comprises a light transmissive electrode and a bonding pad formed on the light transmissive electrode. The semiconductor light emitting device of claim 10, wherein the second electrode further comprises a branch electrode extending from the bonding pad. The semiconductor light emitting device of claim 9, wherein the plurality of semiconductor layers are removed to expose the first semiconductor layer, and the first electrode is formed on the exposed first semiconductor layer. 13. The semiconductor light emitting device of claim 12, wherein the first electrode comprises an electrode for wire bonding and a branch electrode extending from the electrode. The semiconductor light emitting device of claim 13, wherein the plurality of semiconductor layers are removed to expose edges of the first semiconductor layer, and the first electrode extends along the exposed edge of the first semiconductor layer. 8. The semiconductor light emitting device of claim 7, wherein the first electrode is formed on a bottom surface of the substrate. The semiconductor light emitting device of claim 1, wherein the plurality of semiconductor layers are removed to expose edges of the first semiconductor layer, and protrusions are formed on the exposed first semiconductor layers. 13. The semiconductor light emitting device according to claim 12, wherein the removal of the plurality of semiconductor layers for arc formation, protrusion formation, and formation of the first electrode is performed using one mask pattern. The semiconductor light emitting device according to claim 1, wherein the arc is formed in a direction that does not disturb the flow of current. A semiconductor light emitting device having a plurality of semiconductor layers including an active layer that generates light through recombination of electrons and holes, wherein the plurality of semiconductor layers are formed on top of an active layer and a first semiconductor layer having a first conductivity located below the active layer. A semiconductor light emitting device comprising: a second semiconductor layer positioned and having a second conductivity different from the first conductivity; The plurality of semiconductor layers are provided with a trench formed by removing at least a second semiconductor layer and an active layer. The arc is formed in a direction that does not disturb the flow of current, the semiconductor light emitting device. 20. The semiconductor light emitting device according to claim 19, wherein the arc is formed along the electric field direction. 20. The semiconductor light emitting device according to claim 19, wherein a projection for scattering light generated in the active layer is formed on the bottom surface of the arc. The method of claim 19, wherein the first semiconductor layer and second semiconductor layer is made of _{Al x Ga y In 1 -x- y} N (0≤x≤1, 0≤y≤1, 0≤x + y≤1) A semiconductor light emitting device, characterized in that.

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