KR101372846B1 - Method for manufacturing nitride semiconductor light emitting device - Google Patents

Abstract

The present invention provides a method of manufacturing a nitride-based semiconductor light emitting device having a high output power to improve the injection efficiency of the hole by improving the efficiency of light injection due to the difference between the electron and hole mobility and the charge concentration of the nitride-based photoelectric device, the efficiency decrease due to the injection current increase It aims to provide.
Therefore, the present invention has an advantage of improving light emission efficiency by eliminating recombination non-uniformity of electrons and holes by directly injecting holes (holes) into wells that do not contribute to light emission in the active layer of the multi-well structure.

Description

Nitride-based semiconductor light emitting device manufacturing method {METHOD FOR MANUFACTURING NITRIDE SEMICONDUCTOR LIGHT EMITTING DEVICE}

The present invention relates to a method for manufacturing a nitride-based semiconductor light emitting device, and more particularly, to improve the light output due to the difference between the electron and hole mobility and the charge concentration of the nitride-based semiconductor light emitting device, the efficiency reduction problem due to the increase of the injection current A method of manufacturing a high output nitride-based semiconductor light emitting device having improved hole injection efficiency.

The light emitting device is a light emitting device using a phenomenon of emitting light when electrons are transitioned, the light emission of the light emitting device occurs in the process of recombination of the electrons in the semiconductor conduction band (hole) of the valence band (hole) .

The light emitting device is smaller than the conventional light source, has a long lifetime, and has low power and good efficiency because electrical energy is directly converted into light energy. It is also used for display devices such as display devices for automotive instruments, light sources for optical communication, display lamps for various electronic devices, card readers for numeric display devices and calculators.

Recently, light emitting diodes (LEDs) and laser diodes (LDs) using gallium nitride have applications such as large-scale full-color flat panel display devices, traffic lights, indoor lighting and high density light sources, high resolution output systems, and optical communications. As a result, many researchers are attracting attention, and attempts for commercialization are ongoing.

The wavelength of the light emitted by the light emitting element is a band gap function of the semiconductor material used.

Small band gaps require materials with a wider band gap to emit lower energy and longer wavelengths of light, and shorter wavelengths of light.

The light emission wavelength of the light emitting device is controlled by changing the type of impurities added to the semiconductor.

For example, in the case of gallium phosphide, the light emission involving zinc and oxygen atoms is red (wavelength 700 nm), and the light emission involving nitrogen atoms is green (wavelength 550 nm).

On the other hand, silicon carbide (SiC) and Group III nitride-based semiconductors, particularly GaN (gallium nitride), are semiconductor materials having a relatively large bandgap in order to generate light having blue or ultraviolet wavelengths in the spectrum.

In addition to the color itself, the short wavelength light emitting device has an advantage of increasing the storage space of the optical recording device (about four times larger than that of red light).

Among such nitride compound semiconductors for blue light, GaN has no practical technology capable of forming bulk single crystals like other group III nitride systems.

Therefore, a substrate suitable for the growth of GaN crystals should be used, typically a sapphire substrate, that is, an aluminum oxide substrate.

1 is a cross-sectional view of a general light emitting device, in which the n-GaN layer 12, the active layer 13, and the p-GaN layer 14 are sequentially formed on the sapphire substrate 11. Mesa is etched from the p-GaN layer 14 to the n-GaN layer 12. A transparent electrode layer 15 is formed on the upper surface of the p-GaN layer 14, and the transparent electrode layer 15 The p-electrode 16 is formed on the upper portion of the au, and the n-electrode 17 is formed on the mesa-etched n-GaN layer 12.

When the light emitting device 10 thus completed is supplied with a positive load to the p-electrode 16 and a negative load to the n-electrode 17, the p-GaN layer 14 and the n-GaN layer 12 Holes and electrons are collected into the active layer 13 and recombined, respectively, to emit light in the active layer 13.

On the other hand, in nitride-based semiconductors, the difference in electron and hole mobility is caused by 10 times or more due to the relatively large effective mass of the holes, and the hole concentration is 10 times or more smaller than the electron concentration due to the high ionization energy of the p-type dopant.

Therefore, the injected holes with small mobility do not reach or reach the quantum wells on the n-GaN layer 12 side, and thus are generally recombined only in the quantum wells on the p-GaN layer 14 side in the multi-well structure. This occurs, there is a problem that the nonuniformity of the hole in the quantum well of the active layer 13 is not improved.

In addition, the transparent electrode layer 15 formed between the p-GaN layer 14 and the p-electrode 16 is a transparent conducting oxide, which not only reduces total reflection but also has good light transmittance, thereby providing a p-GaN layer. Although there is an advantage in that the extraction efficiency of the light emitted toward 14 can be increased, the transparent electrode layer 15 does not have high conductivity, so the current is not diffused well, and the light injection efficiency of the light emitting device is small due to the small current injection area. There is a problem of lowering.
In addition, Korean Patent Registration No. 10-1158126 (name of the invention: gallium nitride-based light emitting diode) discloses a gallium nitride-based light emitting diode that can increase the luminous efficiency by increasing the current injection area.

In order to solve this problem, the present invention improves the efficiency of light injection due to the difference between the electron and hole mobility and the charge concentration of the nitride-based photoelectric device, the efficiency reduction due to the injection current to improve the injection efficiency of the high output nitride An object of the present invention is to provide a method for manufacturing a semiconductor semiconductor light emitting device.

In order to achieve the above object, the present invention provides a method for manufacturing a nitride-based semiconductor light emitting device, a) a semiconductor by sequentially stacking an n-type semiconductor layer, an undoped undoped semiconductor layer, an active layer and a p-type semiconductor layer on the substrate portion Forming a layer; b) one side of the stacked semiconductor layer is formed by etching the active layer and the p-type semiconductor layer to a predetermined width to form a mesa etching surface exposed to the n-type semiconductor layer, the other side is etching the active layer and p-type semiconductor layer to a predetermined width Thereby forming a vertical electrode surface exposed to the undoped undoped semiconductor layer; c) a transparent electrode layer having vertical electrode portions 171 so that holes (holes) are injected into the upper surface of the p-type semiconductor layer formed in step a) and the vertical electrode surface formed in step b) in the horizontal and vertical directions, respectively; Forming a; And d) forming a p-type electrode and an n-type electrode on an upper portion of the transparent electrode layer and an upper portion of the n-type semiconductor layer exposed through etching.

In addition, step b) according to the invention is characterized in that it further comprises the step of forming an insulating layer on the exposed undoped semiconductor layer.

In addition, the active layer of step a) according to the invention is characterized in that the multi-well well structure.

In addition, the vertical electrode portion of step c) according to the invention is characterized in that the hole is injected from the side of the active layer through tunneling.

The present invention has the advantage that by injecting holes (holes) directly into the wells that do not contribute to light emission in the active layer of the multi-well structure, the light emission efficiency can be improved by eliminating the recombination non-uniformity of the electrons and holes.

In addition, the present invention has an advantage of improving the injection efficiency of the hole by improving the efficiency of light reduction due to the difference between the mobility and charge concentration of electrons and holes of the nitride-based photoelectric device, the efficiency decrease due to the injection current.

1 is a cross-sectional view showing the configuration of a general light emitting device.
Figure 2 is a perspective view showing a light emitting device manufactured by the nitride-based semiconductor light emitting device manufacturing method according to the present invention.
3 is a cross-sectional view illustrating a manufacturing process of a light emitting device according to a first embodiment of the method for manufacturing a nitride based semiconductor light emitting device according to the present invention;
4 is a cross-sectional view illustrating a vertical electrode surface forming process of the nitride-based semiconductor light emitting device manufacturing method according to FIG. 3.
5 is a cross-sectional view illustrating a mesa etching surface forming process of the nitride-based semiconductor light emitting device manufacturing method according to FIG.
6 is a cross-sectional view illustrating a transparent electrode layer forming process of the nitride-based semiconductor light emitting device manufacturing method according to FIG. 3.
7 is a cross-sectional view illustrating an electrode forming process of the nitride-based semiconductor light emitting device manufacturing method according to FIG. 3.
8 is a cross-sectional view showing a light emitting device according to a second embodiment of the method for manufacturing a nitride-based semiconductor light emitting device according to the present invention.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment of the nitride-based semiconductor light emitting device manufacturing method according to the present invention.

(Embodiment 1)

2 is a perspective view showing a light emitting device manufactured by the method for manufacturing a nitride-based semiconductor light emitting device according to the present invention, Figures 3 to 7 is a view showing a manufacturing process of the nitride-based semiconductor light emitting device according to the first embodiment.

2 to 7, the method of manufacturing the nitride based semiconductor light emitting device 100 according to the first embodiment includes forming a semiconductor layer, forming a vertical electrode surface 210, and a transparent electrode layer. And forming the p-type electrode 180 and the n-type electrode 181.

In the forming of the semiconductor layer, the n-type semiconductor layer 130, the undoped undoped semiconductor layer 140, the active layer 150, and the p-type semiconductor layer 160 are sequentially stacked on the substrate unit 110. To form a semiconductor layer.

The substrate unit 110 is preferably a sapphire substrate in consideration of lattice matching with the nitride semiconductor material grown thereon, but is not limited thereto. Silicon carbide, gallium arsenide (GaAs), and gallium nitride (GaN) are preferred. The substrate portion 110 may be formed using aluminum gallium nitride (AlGa1-xN, 0 <= x <1), silicon (Si), or the like.

The n-type semiconductor layer 130, the active layer 150, and the p-type semiconductor layer 160 may be formed on the substrate 110 by organometallic chemical vapor deposition (MOCVD), molecular beam growth (MBE), or hybrid vapor deposition (HVPE). In order to form a semiconductor layer sequentially stacked using a known deposition process, such as).

The n-type semiconductor layer 130 is doped with an appropriate impurity in the process of forming a nitride semiconductor layer made of GaN, AlGaN, GaInN, etc., and the impurities used for the n-type doping are Si, Ge, Se, Te, or C And the like can be used.

In addition, the n-type semiconductor layer 130 forms an undoped non-doped semiconductor layer 120 between the substrate unit 110 and prevents defects from deteriorating due to a sudden change in the lattice cycle. Do it.

In addition, the n-type semiconductor layer 130 is formed with an undoped undoped semiconductor layer 140 having a predetermined thickness between the active layer 150 to prevent the electrostatic discharge (ESD) inside the light emitting device 100 In addition, the surface resistance of the n side can be improved to be close to the surface resistance of the p side (about 10 to 20 Ω per unit area) while ensuring crystallinity.

The active layer 150 is an area where electrons and holes are recombined, and includes InGaN, and the emission wavelength extracted from the light emitting cell is determined according to the type of the material forming the active layer 150, and the active layer 130 Is a multi-layer well structure of a multilayer film in which a quantum well layer and a barrier layer are repeatedly formed.

The p-type semiconductor layer 160 may be doped with an appropriate impurity in the process of forming a nitride semiconductor layer including GaN, AlGaN, GaInN, and the like, and Mg, Zn, or Be may be used as the impurity used for the p-type doping. .

In the forming of the vertical electrode surface 210, one side of the stacked semiconductor layer is etched to the n-type semiconductor layer 130 by etching the active layer 150 and the p-type semiconductor layer 160 to a predetermined width. A surface 200 is formed, and on the other side, the active electrode 150 and the p-type semiconductor layer 160 are etched with a predetermined width to form a vertical electrode surface 210 exposed to the undoped undoped semiconductor layer 140. Be sure to

In the forming of the transparent electrode layer 170, holes (holes) are injected into the upper surface of the stacked p-type semiconductor layer 160 and the vertical electrode surface 210 formed through mesa etching in the horizontal and vertical directions, respectively. The transparent electrode layer 170 having the vertical electrode portion 171 is formed to be formed.

The transparent electrode layer 170 is totally reflected by the light emitted from the light emitting device to reduce the absorption and attenuation inside the light emitting device, ITO (Indium Tin Oxide), IZO (Indium Zinc Oxide), ZnO (Zinc Oxide) Or it may be made of a material such as ZCO (Zinc Carbon Oxide), preferably made of ITO.

In addition, when the current is supplied to the p-type electrode 180, the transparent electrode layer 170 allows the supplied current to be evenly supplied, and the vertical electrode part 171 formed in the vertical direction on the side of the vertical electrode surface 210. The barrier electrode is formed on the side of the active layer 150 of the semiconductor layer to directly inject holes into the various wells of the active layer through the vertical electrode part 171 to have a relatively high hole concentration and mobility. .

That is, the holes of the p-type semiconductor layer 160 are heavy and have low mobility, and thus, holes are not diffused well. This is because recombination is performed only in the p-type semiconductor side quantum well in the active layer 150 of the multi-well structure. In addition, since the current is injected into only a part of the active layer 150 instead of the entire area, the light is not formed over the entire area of the active layer 150, and the injection of a large amount of current to increase the output is also limited. do.

Accordingly, the vertical electrode part 171 forms a barrier electrode in the vertical direction on the side surface of the active layer 150 so that electrons or holes that are separated from adjacent wells can easily move to adjacent wells with little interaction. Tunneling allows holes to be injected from the side of the active layer 150.

The tunneling may be formed of any one of a schottky barrier or a tunnel barrier, and the holes supplied from the vertical electrode portion 171 to the active layer 150 may be increased to induce smooth movement of current and generation of high yield light. Will be.

The forming of the p-type electrode 180 and the n-type electrode 181 may include the p-type electrode 180 and the upper portion of the n-type semiconductor layer 130 exposed through etching and the upper portion of the transparent electrode layer 170, respectively. An n-type electrode 181 is formed.

The p-type electrode 180 is formed of Au or AU alloy on the transparent electrode layer 170 to be formed through an organometallic chemical vapor deposition method or the like by sputtering or the like, and the n-type electrode 181 Silver is formed on the n-type semiconductor layer 130 exposed through etching by using a material selected from the group consisting of Ti, Cr, Al, Cu, and Au, or by a process such as sputtering or deposition through an organometallic chemical vapor deposition method. .

(Second Embodiment)

As shown in FIG. 8, the nitride-based semiconductor light emitting device 100 ′ according to the second embodiment includes forming a semiconductor layer, forming a vertical electrode surface 210, and an undoped semiconductor layer 140. Forming an insulating layer 190 on the substrate, forming a transparent electrode layer 170, and forming a p-type electrode 180 and an n-type electrode 181.

In the forming of the semiconductor layer, the n-type semiconductor layer 130, the undoped undoped semiconductor layer 140, the active layer 150, and the p-type semiconductor layer 160 are sequentially stacked on the substrate unit 110. To form a semiconductor layer.

An undoped undoped semiconductor layer 120 may be formed between the substrate 110 and the n-type semiconductor layer 130.

In the forming of the vertical electrode surface 210, one side of the stacked semiconductor layer is etched to the n-type semiconductor layer 130 by etching the active layer 150 and the p-type semiconductor layer 160 to a predetermined width. A surface 200 is formed, and on the other side, the active electrode 150 and the p-type semiconductor layer 160 are etched with a predetermined width to form a vertical electrode surface 210 exposed to the undoped undoped semiconductor layer 140. Be sure to

The step of forming the insulating layer 190 on the undoped semiconductor layer 140 is to insulate between the n-type semiconductor layer 130 and the transparent electrode layer 170 deposited in the vertical direction, the transparent electrode layer 170 The semiconductor layer 140 is deposited on the undoped undoped semiconductor layer 140 exposed through mesa etching from the vertical electrode unit 171 of FIG. 9 to prevent contact with the n-type semiconductor layer 130.

In addition, SiO 2 is generally used as a material that may be used as the insulating layer 190, and in addition, insulating materials such as Si 3 N 4 and Al 2 O 3 may be used.

In the forming of the transparent electrode layer 170, holes (holes) are injected into the upper surface of the stacked p-type semiconductor layer 160 and the vertical electrode surface 210 formed through mesa etching in the horizontal and vertical directions, respectively. The transparent electrode layer 170 having the vertical electrode portion 171 is formed to be formed.

The forming of the p-type electrode 180 and the n-type electrode 181 may include the p-type electrode 180 and the upper portion of the n-type semiconductor layer 130 exposed through etching and the upper portion of the transparent electrode layer 170, respectively. An n-type electrode 181 is formed.

Therefore, by directly injecting holes (holes) into the quantum wells that do not contribute to light emission in the active layer of the multi-well structure, the recombination non-uniformity of the electrons and holes can be solved to improve the luminous efficiency, the electron and hole of the nitride-based photoelectric device It is possible to provide the nitride-based semiconductor light emitting device 100 which improves the injection efficiency of the hole by improving the light output decrease due to the difference in mobility and the charge concentration and the efficiency reduction caused by the injection current.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the appended claims. It can be understood that

In the course of the description of the embodiments of the present invention, the thicknesses of the lines and the sizes of the components shown in the drawings may be exaggerated for clarity and convenience of explanation, , Which may vary depending on the intentions or customs of the user, the operator, and the definitions of these terms should be based on the contents throughout this specification.

100: Light emitting element
110:
120: undoped semiconductor layer
130: n-type semiconductor layer
140: undoped semiconductor layer
150: active layer
160: p-type semiconductor layer
170: transparent electrode layer
171: vertical electrode portion
180: p-type electrode
181 n-type electrode
190: insulation layer
200: vertical electrode surface
210: mesa etching surface

Claims (4)

A nitride-based semiconductor light emitting device manufacturing method,
a) forming a semiconductor layer by sequentially stacking an n-type semiconductor layer 130, an undoped undoped semiconductor layer 140, an active layer 150, and a p-type semiconductor layer 160 on the substrate unit 110. step;
b) one side of the stacked semiconductor layer is formed by etching the active layer 150 and the p-type semiconductor layer 160 to a predetermined width to form a mesa etching surface 200 exposed to the n-type semiconductor layer 130, the other side Etching the active layer 150 and the p-type semiconductor layer 160 to a predetermined width to form a vertical electrode surface 210 exposed to the undoped undoped semiconductor layer 140;
c) a vertical electrode part (hole) is injected into the upper surface of the p-type semiconductor layer 160 formed in step a) and the vertical electrode surface 210 formed in step b) in a horizontal direction and a vertical direction, respectively ( Forming a transparent electrode layer 170 having 171; And
d) forming a p-type electrode 180 and an n-type electrode 181 on the upper portion of the transparent electrode layer 170 and the n-type semiconductor layer 130 exposed through etching, respectively. Light emitting device manufacturing method.
The method of claim 1,
e) the step b) further comprises the step of forming an insulating layer (190) on the exposed undoped semiconductor layer (140).
3. The method according to claim 1 or 2,
The active layer 150 of step a) is a nitride-based semiconductor light emitting device manufacturing method characterized in that the multi-well well structure.
3. The method according to claim 1 or 2,
The vertical electrode part 171 of step c) is a method of manufacturing a nitride-based semiconductor light emitting device, characterized in that the hole is injected from the side of the active layer 150 through tunneling.

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