KR100882977B1 - Method of manufacturing light emitting device - Google Patents

Abstract

The present invention relates to a method of manufacturing a light emitting device, wherein an N-GaN layer, an active layer, a diffusion barrier layer, a first P-GaN layer, and a dopant having a lower P-type carrier concentration than the first P-GaN layer are formed on a sapphire substrate. A first step of sequentially growing 2 P-GaN layers; Performing a heat treatment process to diffuse the P-type carriers of the first P-GaN layer and the second P-GaN layer to form the diffusion barrier layer, the first P-GaN layer, and the second P-GaN layer; A second step of forming a P-GaN layer in which carriers are uniformly distributed; Mesa etching from the P-GaN layer to a part of the N-GaN layer; Forming a P-electrode pad on the P-GaN layer and forming an N-electrode pad on the etched N-GaN layer.

Therefore, the present invention grows a diffusion barrier layer that is not doped with Mg prior to P-GaN growth grown at high temperature and high concentration of Mg, thereby preventing Mg from penetrating into the active layer by high temperature diffusion, thereby preventing Mg into the active layer. It is possible to suppress the generation of defects due to diffusion, thereby improving the characteristics of the device.

Nitride, Light Emitting Diode, Diffusion, Mg, Prevention Layer

Description

Method of manufacturing light emitting device

1 is a cross-sectional view of a general light emitting device.

2 is a schematic energy band diagram of a light emitting device according to the prior art.

3A and 3B are schematic Mg concentration distribution diagrams of before and after diffusion of a P-GaN layer in a light emitting device according to the prior art.

Figures 4a to 4c is a manufacturing process of the light emitting device according to the present invention.

5A and 5B are schematic Mg concentration distribution diagrams of before and after diffusion of a P-GaN layer in a light emitting device according to the present invention.

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

100: sapphire substrate 110,110a: N-GaN layer

120: active layer 130: diffusion barrier layer

131,132,150: P-GaN layer 161: P-electrode pad

162: N-electrode pad

The present invention relates to a method of manufacturing a light emitting device, and more particularly, before the growth of P-GaN grown under high temperature and high concentration of Mg doping, by growing a diffusion barrier layer that is not doped with Mg, Mg is active layer by high temperature diffusion. The present invention relates to a method of manufacturing a light emitting device capable of preventing the penetration of light into the active layer and suppressing the generation of defects due to Mg diffusion into the active layer to improve device characteristics.

In general, the light emitting device using the nitride compound semiconductor has been widely used in various fields.

In particular, LDs and LEDs using these materials are essential for the development of full color displays, displays such as traffic lights, and high density optical recording.

1 is a cross-sectional view of a general light emitting device, an N-compound semiconductor layer 101 formed on an upper portion of a substrate 100 and etched a portion of the upper portion thereof; An active layer 111 formed on an unetched top of the N-compound semiconductor layer 101; A P-compound semiconductor layer 102 formed on the active layer 111; A current spreading transparent electrode 105 formed on the P-compound semiconductor layer 102; A P-electrode 107 formed on the current spreading transparent electrode 105; The N-electrode 108 is formed on the etched top of the N-compound semiconductor layer.

When holes and electrons are injected from the P-electrode 107 and the N-electrode 108, holes and electrons are recombined in the active layer 111 to emit light.

FIG. 2 is a schematic energy band diagram of a light emitting device according to the prior art, in which an active layer is formed in a well shape between an N-GaN layer and a P-GaN layer, which includes electrons and P- from the N-GaN layer. Holes are injected from the GaN layer, and electrons and holes are recombined in a confined state in the well to emit light.

3A and 3B are schematic Mg concentration distribution diagrams of before and after diffusion of a P-GaN layer in a light emitting device according to the prior art, in which Mg, a P type dopant, is constantly injected during the growth of a GaN layer, As shown, the Mg concentration of the P-GaN layer is constant before diffusion.

When the diffusion process is performed, as shown in FIG. 3B, Mg of the P-GaN layer penetrates into the active layer, which causes deterioration of device characteristics.

On the other hand, one of the biggest difficulties remaining until now in manufacturing a light emitting device using a nitride compound semiconductor is that the activation efficiency of Mg used as a doping material is lower than the hole concentration to obtain a P-GaN layer having a high hole concentration. Much higher amounts of Mg must be doped, which makes it difficult to avoid defects.

The excessively doped Mg does not only generate defects in the P-GaN layer itself, but also has a growth temperature of about 1000 ° C., which may cause defects in other adjacent layers by diffusion during the growth time.

In particular, as shown in FIG. 3B, if Mg diffuses and penetrates into the active layer during the growth of the P-GaN layer or during the heat treatment process, the characteristics of the device are significantly degraded.

The present invention has been made to solve the problems described above, and before the growth of P-GaN grown under high temperature and high concentration of Mg doping, by growing a diffusion barrier layer that is not doped with Mg, Mg by high temperature diffusion It is an object of the present invention to provide a method of manufacturing a light emitting device capable of preventing penetration into the active layer, thereby suppressing defect generation due to Mg diffusion into the active layer, thereby improving the characteristics of the device.

A preferred aspect for achieving the above object of the present invention is a P-type carrier on the sapphire substrate than the N-GaN layer, the active layer, the diffusion barrier layer, the first P-GaN layer and the first P-GaN layer. A first step of sequentially growing a second P-GaN layer doped with a small concentration of;

Performing a heat treatment process to diffuse the P-type carriers of the first P-GaN layer and the second P-GaN layer to form the diffusion barrier layer, the first P-GaN layer, and the second P-GaN layer; A second step of forming a P-GaN layer in which carriers are uniformly distributed;

Mesa etching from the P-GaN layer to a part of the N-GaN layer;

A method of manufacturing a light emitting device comprising a fourth step of forming a P-electrode pad on the P-GaN layer and forming an N-electrode pad on the etched N-GaN layer is provided.

Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings.

4A to 4C illustrate a manufacturing process of the nitride-based light emitting device according to the present invention. The N-GaN layer 110, the active layer 120, the diffusion barrier layer 130, and the first P-GaN layer are disposed on the sapphire substrate 100. 131 and a second P-GaN layer 132 doped with a smaller concentration of a P-type carrier than the first P-GaN layer 131 are sequentially grown (FIG. 4A).

The diffusion barrier layer 130 is a layer for preventing diffusion of the P-type carrier from the P-GaN layer, and is formed of an undoped GaN layer.

Here, the first P-GaN layer 131 and the second P-GaN layer 132 is formed by doping Mg while growing the GaN layer, the first P-GaN layer 131 is the second P It is formed by doping 10-20% Mg more than -GaN layer 132.

Referring to FIG. 5A, Mg concentrations of the undoped GaN layer, the first P-GaN layer 131, and the second P-GaN layer 132, which are the diffusion barrier layer 130, may be known.

At this time, the thickness of the first P-GaN layer 131 is preferably grown to 10 ~ 30nm.

The first P-GaN layer 131 having a large P-type carrier concentration is formed in order to minimize the decrease in electrical conductivity as the diffusion barrier layer 130, that is, the undoped GaN layer is inserted.

Next, a P-type carrier of the diffusion barrier layer 130, the first P-GaN layer 131, and the second P-GaN layer 132 is diffused by performing a heat treatment process, so that the P-type concentration is uniform. A GaN layer 150 is formed (FIG. 4B).

Here, referring to FIG. 5B, the heat treatment process activates the P-type carriers of the first P-GaN layer 131 and the second P-GaN layer 132, so that the P-type carriers are formed on both layers. The concentration is uniform and the P-type carrier of the first P-GaN layer 131 to be diffused is almost trapped in the diffusion barrier layer 130 so that the active layer 120 is not affected.                     

Thereafter, Mesa is etched from the P-GaN layer 150 to a part of the N-GaN layer 110 (FIG. 4C).

Finally, a P-electrode pad 161 is formed on the P-GaN layer 150, and an N-electrode pad 162 is formed on the etched N-GaN layer 110a. 4d)

As described above, the present invention is to prevent the penetration of Mg into the active layer by high temperature diffusion by growing a diffusion preventing layer that is not doped with Mg before the growth of P-GaN grown under high temperature and high concentration of Mg doping. In addition, there is an effect that the characteristics of the device can be improved by suppressing defect generation due to Mg diffusion into the active layer.

Although the invention has been described in detail only with respect to specific examples, it will be apparent to those skilled in the art that various modifications and variations are possible within the spirit of the invention, and such modifications and variations belong to the appended claims.

Claims (4)

An N-GaN layer, an active layer, a diffusion barrier layer, a first P-GaN layer, and a second P-GaN layer doped with a lower P-type carrier concentration than the first P-GaN layer in order to sequentially grow on the sapphire substrate; Step 1; Performing a heat treatment process to diffuse the P-type carriers of the first P-GaN layer and the second P-GaN layer to form the diffusion barrier layer, the first P-GaN layer, and the second P-GaN layer; A second step of forming a P-GaN layer in which carriers are uniformly distributed; Mesa etching from the P-GaN layer to a part of the N-GaN layer; Forming a P-electrode pad on the P-GaN layer, and forming an N-electrode pad on the etched N-GaN layer, The diffusion barrier layer is a light emitting device, characterized in that the undoped GaN layer. delete The method of claim 1, The first P-GaN layer is formed by doping 10% to 20% more Mg than the second P-GaN layer. The method according to claim 1 or 3, The thickness of the first P-GaN layer is a method of manufacturing a light emitting device, characterized in that 10 ~ 30nm.

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