KR100696194B1 - Nitride semiconductor light emitting device and preparing method of the same - Google Patents

Abstract

A nitride semiconductor light emitting device and a method for manufacturing the same are provided to enhance external quantum efficiency and to reduce the area of a metal electrode by forming a through hole in a P-type electrode. An n-type electrode(112), an active layer(113) and a p-type electrode(114) are sequentially stacked on a substrate(110). An open region is formed for contacting an n-type metal contact layer to the n-type electrode. A hole(118) is formed to elongate the n-type electrode through the p-type electrode and the active layer. A reflective layer(119) is formed at the bottom of the hole. An n-type metal contact layer is formed on the open region. A transparent metal film is formed on the p-type electrode. A p-type metal contact layer is formed on the transparent metal film.

Description

Nitride semiconductor light emitting device and its manufacturing method {Nitride semiconductor light emitting device and preparing method of the same}

1 is a cross-sectional view of a conventional nitride semiconductor light emitting device.

2A is a cross-sectional view of a nitride semiconductor light emitting device according to an embodiment of the present invention.

Figure 2b is a plan view of a nitride semiconductor light emitting device according to the present invention.

FIG. 2C is a cross-sectional view taken along line AA ′ of FIG. 2B;

Figure 3 is a schematic diagram illustrating the principle of the nitride semiconductor light emitting device according to the present invention.

4A to 4F are cross-sectional views sequentially illustrating a method of manufacturing a nitride semiconductor according to the present invention.

<Description of the symbols for the main parts of the drawings>

110 substrate 111 buffer layer

112: n-type electrode layer 113: active layer

114: p-type electrode layer 115: transparent metal layer

116: p-type metal contact layer 117: n-type metal contact layer

119: reflective layer

The present invention relates to a compound semiconductor, and more particularly, to a light emitting device using a nitride semiconductor and a method for manufacturing the same.

Nitride-based compound semiconductors (III-Nitride, for example, GaN) are direct-transition semiconductors that can control wavelengths from visible light to ultraviolet light. It has superior physical properties compared to InP compound semiconductors. Based on these characteristics, existing compound semiconductors such as optical devices such as light emitting diodes (LEDs) and laser diodes (LDs) in the visible region, and electronic devices used in next-generation wireless communication and satellite communication systems requiring high power and high frequency characteristics. The scope of application is expanding to areas with limitations.

1 illustrates a light emitting device using a conventional nitride compound semiconductor. The light emitting element basically includes an n-type electrode layer 12 using a nitride semiconductor, a p-type electrode layer 14 and an active layer 13 formed between the electrode layers. At this time, the active layer 13 is composed of InGaN, InAlGaN, etc., the light emission characteristics depend on the p-type electrode layer 14 which draws light emitted from the active layer 13 to the outside.

However, it is difficult to increase the internal quantum efficiency due to the lattice mismatch between the active layer and the electrode layer, and the growth temperature. In particular, there is a limit in increasing the hole concentration and mobility of the p-type electrode layer, so as to manufacture a high output light emitting device. Currently, research is being conducted to increase the external quantum efficiency of light emitting devices.

The present invention has been made to solve the above problems, the present invention by forming a light emitting device having a specific structure, the external quantum efficiency of light emitted from the active layer is increased, the operating temperature of the device is a nitride semiconductor light emitting device The purpose is to provide.

According to the present invention, a nitride semiconductor light emitting device including an n-type electrode layer, an active layer, and a p-type electrode layer sequentially stacked on a substrate is characterized by including a hole passing through the p-type electrode layer and the active layer.

At this time, the hole is preferably characterized in that extending to the n-type electrode layer.

At this time, the inclination angle θ formed by the wall surface of the hole with the substrate surface is 0 <θ <90 °, and at least one or more angles are preferably provided.

At this time, the holes are preferably arranged at regular intervals.

In addition, the total area occupied by the holes in the light emitting area is preferably 30 to 70% of the total light emitting area.

In addition, the bottom of the hole is preferably provided with a reflective layer for reflecting the emitted light.

In addition, the reflective layer is preferably formed lower than the height of the active layer.

In addition, the reflective layer may be formed of at least one material selected from the group consisting of metal, titanium oxide, and silicon oxide.

A method of manufacturing a nitride semiconductor light emitting device according to the present invention includes a step of sequentially laminating an n-type electrode layer, an active layer, and a p-type electrode layer on a substrate, and an n-type metal contact layer on the n-type electrode layer. A second step of forming an exposed area for contacting; a third step of forming a hole penetrating through the p-type electrode layer and the active layer and extending to a predetermined depth of the n-type electrode layer; and a forming of a reflective layer on a bottom surface of the hole A fourth step of forming an n-type metal contact layer in the exposed region, a sixth step of forming a transparent metal layer on the p-type electrode layer, and a seventh step of forming a p-type metal contact layer on the transparent metal layer Characterized in that it comprises a step.

In this case, the hole is preferably formed by a dry etching method, and the reflective layer is preferably selected from the group consisting of a sputtering method, an E-beam deposition method, and an atomic layer deposition method (ALD).

Hereinafter, an embodiment of the nitride semiconductor light emitting device according to the present invention will be described in more detail with reference to FIGS. 2A to 2C.

2A is a cross-sectional view of a nitride semiconductor light emitting device according to an embodiment of the present invention, FIG. 2B is a plan view of a nitride semiconductor light emitting device according to the present invention, and FIG. 2C is a cross-sectional view taken along line AA ′ of FIG. 2B.

Accordingly, in the nitride semiconductor light emitting device, the substrate 110, the buffer layer 111, the n-type electrode layer 112, the active layer 113, and the p-type electrode layer 114 are sequentially stacked, and the n-type electrode layer 112 is exposed. The n-type metal contact layer 117 is provided on the region, and the transparent metal layer 115 and the p-type metal contact layer 116 are sequentially provided on the p-type electrode layer. In addition, a hole 118 penetrates the p-type electrode layer 114 and the active layer 113 and extends to a predetermined depth of the n-type electrode layer 112, and a reflective layer 119 is formed at the bottom of the hole 118. It is provided.

In the nitride semiconductor light emitting device having the above-described configuration, structures and materials of the substrate 110, the buffer layer 111, the n-type electrode layer 112, the active layer 113, the p-type electrode layer 114, and the transparent metal layer 115 are Non-limiting in the present invention, the configuration is well known, so detailed description on the page is omitted.

In this embodiment, the hole 118 is formed to reduce the non-uniformity of the luminescence properties caused by the low hole concentration and mobility of the p-type electrode layer 114. Therefore, the holes 118 are formed in plural as shown in FIG. 2B, and the holes 118 are preferably arranged at uniform intervals. At this time, those skilled in the art will recognize that the manner in which the arrangement is not limited.

The area occupied by the holes 118 in the light emitting area is preferably, but is not limited to, 30 to 70% of the total light emitting area. If less than 30%, the effect of eliminating nonuniformity of light emission is small, and if it exceeds 70%, the area occupied by the organic light emitting layer that emits light becomes small, so that luminous efficiency is not good. At this time, the area occupied by the holes 118 in the light emitting area relatively reduces the use of the electrode layer, thereby reducing the heat generation of the device, thereby reducing the operating temperature.

In addition, the hole 118 is preferably extended from the top to the n-type electrode layer 112, most of the light is generated between the p-type electrode layer 114 and the active layer 113, but the active layer 113 This is because the holes are formed in the contact portion between the n-type electrode layer 115 and the active layer 113 according to the conditions, and thus, the formation of holes up to the n-type electrode layer 115 may further increase the external quantum efficiency.

The hole 118 may be manufactured such that the diameter of the hole 118 decreases from the top to the bottom, that is, the inclination angle θ of the hole wall surface with respect to the substrate surface is 0 ° <θ <90 °. The inclination angle is preferably determined to maximize the refraction of light to the outside in the wavelength of the light emitting device and the stacked structure of the light emitting device, thereby increasing the external quantum efficiency.

The shape of the hole 118 is shown as a circle in this embodiment, but is not limited thereto, and may have a rectangular or triangular shape.

In addition, a reflective layer 119 is formed on the bottom of the hole 118, and the material of the reflective layer 119 may be a metal (eg, gold), titanium oxide, or silicon oxide capable of reflecting the emission wavelength. At this time, the thickness of the reflective layer 119 is about 10 to 100 nm, preferably formed below the height of the active layer 113.

3 is a schematic diagram illustrating the principle of the nitride semiconductor light emitting device according to the present invention, and the operation of the hole and the reflective layer applied in this embodiment will be described in more detail.

The light emitted from the active layer 113 propagates in all directions, and the light propagated in the horizontal direction enters a hole with a different refractive index, thereby changing the direction of travel, and is reflected from the reflective layer and directed upward. In addition, the light propagated obliquely to the bottom surface of the active layer 113 is reflected by the n-type electrode layer 112 is entered into the hole with a different refractive index is directed to the top to increase the luminous efficiency.

Hereinafter, a method of manufacturing a nitride semiconductor light emitting device according to the present invention will be described in more detail with reference to FIGS. 4A to 4F.

4A illustrates a step of sequentially stacking an n-type electrode layer 112, an active layer 113, and a p-type electrode layer 114 on a substrate. Sapphire may be used as a substrate material, and n may be n-type nitride semiconductor. The type electrode layer 112 is formed, an active layer 113 such as InGaN is formed on the n-type electrode layer 112, and the p-type electrode layer 114 is formed on the active layer 113 with a p-type nitride semiconductor. Each layer can be formed using a variety of known deposition methods.

4B illustrates a step of forming an exposed region for contacting the n-type metal contact layer 117 that applies power to the n-type electrode layer 112.

4C is a step of forming a hole 118 that penetrates the p-type electrode layer 114 and the active layer 113 and extends to the n-type electrode layer 112, wherein the hole 118 preferably uses a dry etching method. The inclination angle may be formed in consideration of an etching condition and an etching pattern.

4D illustrates the step of forming a reflective layer on the bottom of the hole. The reflective layer 119 is formed of a metal (for example, gold), titanium oxide, or silicon oxide using a sputtering method, an E-beam deposition method, or the like.

4E is a step of forming the transparent metal layer 115 on the p-type electrode layer 114, the transparent metal layer is not formed on the hole 118. 4F also illustrates forming the p-type metal contact layer 116 on the transparent metal layer 115.

Although the present invention has been described primarily with reference to the above embodiments, many other possible modifications and variations can be made without departing from the spirit and scope of the invention. For example, those skilled in the art will recognize that the shape of the hole, the thickness of the reflective layer, the limitation of the material, etc. can be easily made.

The nitride semiconductor light emitting device according to the present invention is provided with a hole penetrating through the P-type electrode layer to reduce the nonuniformity of light emission, thereby enabling the manufacture of a large area device. In addition, by reducing the area occupied by the metal electrode in the light emitting area, there is an effect that the operating temperature can be lowered, and the emitted light is refracted and reflected, thereby increasing the external quantum efficiency.

The scope of the above-described invention is defined in the following claims, not bound by the description in the text of the specification, all modifications and variations belonging to the equivalent scope of the claims will fall within the scope of the invention.

Claims (12)

In a nitride semiconductor light emitting device comprising an n-type electrode layer, an active layer, and a p-type electrode layer sequentially stacked on a substrate, A nitride semiconductor light emitting device comprising a hole passing through the p-type electrode layer and the active layer. The method of claim 1, The hole extends to the n-type electrode layer, nitride semiconductor light emitting device. The method of claim 1, And an inclination angle θ formed by the wall surface of the hole with the substrate surface is 0 <θ <90 °. The method of claim 1, At least one hole is provided with a nitride semiconductor light emitting device. The method of claim 1, The hole is nitride semiconductor light emitting device, characterized in that arranged at regular intervals. The method of claim 1, The total area occupied by the holes in the light emitting area is 30 to 70% of the total light emitting area area. The method of claim 1, A nitride semiconductor light emitting device, characterized in that the bottom surface of the hole is further provided with a reflective layer for reflecting the emitted light. The method of claim 7, wherein The reflective layer is formed of a nitride semiconductor light emitting device, characterized in that lower than the height of the active layer. The method of claim 7, wherein And the reflective layer is formed of at least one material selected from the group consisting of metals, titanium oxides and silicon oxides. A first step comprising sequentially laminating an n-type electrode layer, an active layer, and a p-type electrode layer on a substrate, A second step of forming an exposed area for contacting the n-type electrode layer with the n-type metal contact layer, A third step of forming a hole penetrating through the p-type electrode layer and the active layer and extending to a predetermined depth of the n-type electrode layer, A fourth step of forming a reflective layer on the bottom of the hole, A fifth step of forming an n-type metal contact layer in the exposed region, A sixth step of forming a transparent metal layer on the p-type electrode layer, and And a seventh step of forming a p-type metal contact layer on the transparent metal layer. The method of claim 10, The hole is a method of manufacturing a nitride semiconductor light emitting device, characterized in that formed by a dry etching method. The method of claim 10, The reflective layer is a method of manufacturing a nitride semiconductor light emitting device, characterized in that formed by sputtering or E-beam deposition method.

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