KR101761617B1 - Semiconductor light emitting device of vertical topology - Google Patents

Abstract

The present invention relates to a semiconductor light emitting device, and more particularly, to a vertical nitride semiconductor light emitting device. The present invention provides a semiconductor device comprising: a conductive substrate; A first electrode located on the substrate; A first conductive semiconductor layer located on the first electrode; An active layer located on the first conductive semiconductor layer; A second conductive semiconductor layer located on the active layer; A current spreading layer located in the second conductive semiconductor layer; And a second electrode located on the second conductive semiconductor layer.

Description

[0001] The present invention relates to a vertical semiconductor light emitting device,

The present invention relates to a semiconductor light emitting device, and more particularly, to a vertical nitride semiconductor light emitting device.

Light emitting diodes (LEDs) are well-known semiconductor light emitting devices that convert current into light. In 1962, red LEDs using GaAsP compound semiconductors were commercialized. GaP: N series green LEDs and information communication devices As a light source for a display image of an electronic device.

Nitride compound semiconductors typified by gallium nitride (GaN) have high thermal stability and wide bandgap (0.8 to 6.2 eV), attracting much attention in the field of high-output electronic component development including LEDs come.

One of the reasons for this is that GaN can be combined with other elements (indium (In), aluminum (Al), etc.) to produce semiconductor layers emitting green, blue and white light.

Since the emission wavelength can be controlled in this manner, it can be tailored to the characteristics of the material according to the specific device characteristics. For example, GaN can be used to create a white LED that can replace the blue LEDs and incandescent lamps that are beneficial for optical recording.

Therefore, nitride-based semiconductors are currently used as a base material in the fabrication of blue / green laser diodes and light emitting diodes (LEDs). In particular, high-power LEDs are attracting attention as a white light source, and the future of LED lighting is foreseen.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a vertical type semiconductor light emitting device capable of suppressing the current densification phenomenon by uniformly injecting current into the active layer region in a light emitting device and realizing an efficient vertical light emitting device do.

Another object of the present invention is to provide a vertical semiconductor light emitting device capable of realizing an efficient horizontal large-area light emitting device without loss of the light emitting area of the active layer region.

According to an aspect of the present invention, there is provided a semiconductor device comprising: a conductive substrate; A first electrode located on the substrate; A first conductive semiconductor layer located on the first electrode; An active layer located on the first conductive semiconductor layer; A second conductive semiconductor layer located on the active layer; A current spreading layer located in the second conductive semiconductor layer; And a second electrode located on the second conductive semiconductor layer.

The present invention has the following effects.

In the vertical type nitride semiconductor light emitting device (LED), the current distribution layer is applied to control the current flow between the n-type electrode and the p-type electrode, so that the path through which the current flows can be freely controlled.

Thus, the current dispersion effect of the light emitting device can be maximized, and the light output can be improved through the uniform light distribution of the vertical light emitting device.

The application of such a current-spreading layer allows a wide variety of structures (patterns and depths) to be freely applied by the design elements, making it possible to effectively utilize the active layer region and to maximize light output through effective current path control of the light- You can.

1 is a cross-sectional view showing an example of a vertical light emitting device.
2 is a schematic diagram showing the current flow of the structure of FIG.
3 is a cross-sectional view showing another example of the vertical light emitting device and current flow.
4 is a cross-sectional view showing a first example of a light-emitting device including a current-spreading layer.
5 is a schematic diagram illustrating the current flow of the structure of FIG.
6 to 13 are cross-sectional views illustrating a manufacturing process of the light emitting device.
14 is a cross-sectional view showing a second example of a light-emitting element including a current-spreading layer.
15 is a cross-sectional view showing a third example of a light-emitting element including a current-spreading layer.
16 is a schematic diagram showing the current flow of the structure of FIG.
17 is a cross-sectional view showing a fourth example of a light-emitting device including a current-spreading layer.
18 is a cross-sectional view showing a fifth example of a light-emitting element including a current-spreading layer.
19 is a cross-sectional view showing a sixth example of a light emitting device including a current dispersion layer.

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

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. Rather, the intention is not to limit the invention to the particular forms disclosed, but rather, the invention includes all modifications, equivalents and substitutions that are consistent with the spirit of the invention as defined by the claims.

It will be appreciated that when an element such as a layer, region or substrate is referred to as being present on another element "on," it may be directly on the other element or there may be an intermediate element in between .

Although the terms first, second, etc. may be used to describe various elements, components, regions, layers and / or regions, such elements, components, regions, layers and / And should not be limited by these terms.

1, the nitride-based semiconductor light emitting device having a vertical electrode structure includes a p-type electrode 20, a nitride semiconductor structure 30, and an n- Type electrode 40 is positioned.

The nitride semiconductor structure 30 includes a p-type nitride semiconductor layer 31, an active layer 32, and an n-type nitride semiconductor layer 33.

In this case, the current flow can be schematically shown as in Fig. That is, holes can be uniformly injected into the active layer 32 through the p-type electrode 20, but the n-type electrode 40 is locally located in the n-type nitride semiconductor layer 33, Infusion can be concentrated in area A.

3, an insulating film 50 such as SiO ₂ is formed in a region where a current can be concentrated between the p-type electrode 20 and the p-type nitride semiconductor layer 31 Can be improved. In this case, the current and the recombination distribution due to the supply paths of electrons and holes as shown in FIG. 3 are shown.

In this structure, the p-type nitride semiconductor layer 31 has a very high resistivity of about several ohm-cm, so holes may not be injected in the region of the active layer 32 above the insulating film 50, ), Light emission by recombination of holes and electrons may not occur.

3, the larger the width of the insulating film 50, the larger the current dispersion effect can be. However, the non-emission region B on the insulating film 50 can be increased, Lt; / RTI >

4 shows a vertical light emitting device structure including a current spreading layer 500 in an n-type nitride semiconductor layer 330. In FIG.

In this light emitting device structure, a p-type electrode 200 is disposed on a conductive substrate 100, a semiconductor structure 300 is disposed on the p-type electrode 200, and an n-type electrode 400 ).

In the semiconductor structure 300, the p-type nitride semiconductor layer 310 is located on the p-type electrode 200, and the active layer 320 and the n-type nitride semiconductor layer 330 are sequentially disposed thereon.

Of course, in some cases, the positions of the p-type electrode 200, the n-type electrode 400, and the semiconductor structure 300 may be reversed. That is, the n-type electrode 400 and the n-type nitride semiconductor layer 330 may be positioned close to the lower conductive substrate 100.

As described above, a current spreading layer 500 having an insulating property is located in the n-type nitride semiconductor layer 330. The current spreading layer 500 is formed of a p-type electrode 200, type electrode 400 may be located on the current flow path between the n-type electrode 400 and the n-

The current spreading layer 500 may be formed by inserting the n-type nitride semiconductor layer 330 into the n-type nitride semiconductor layer 330. That is, the current-spreading layer 500 can use an insulated nitride semiconductor layer.

The n-type dopant and the p-type dopant may be mixed with each other to insulate the current-spreading layer 500 using the insulated nitride semiconductor layer.

The current spreading layer 500 may be positioned substantially parallel to the active layer 320. In addition, the current-spreading layer 500 may be located close to the outer surface of the n-type nitride semiconductor layer 330 where the n-type electrode 400 is located.

The thickness of the current spreading layer 500 may be determined considering the structure of the light emitting device, the insulating property, the thickness of the semiconductor layer, the doping, etc., and may have a thickness of about 10 nm or more, Type nitride semiconductor layer 330 may be thinner than the thickness of the n-type nitride semiconductor layer 330.

The area of the current-spreading layer 500 may be larger than the area of the n-type electrode 400.

In the light-emitting device having such a current-spreading layer 500, the current flow may be as shown in FIG. 5 depending on the supply of electrons and the supply path of holes.

In general, the specific resistance of the p- type nitride semiconductor is approximately several Ωcm, a resistivity of the n- type nitride semiconductor is 10 ^-3 Ωcm long, very low specific resistance of the n- type nitride semiconductor than the p- type semiconductor.

4, the electrons supplied through the n-type electrode 400 on the current spreading layer 500 having an insulating property inserted in the n-type nitride semiconductor layer 330 are injected in the horizontal direction Can be effectively dispersed.

The current flowing horizontally in the n-type nitride semiconductor layer 330 under the current-spreading layer 500 becomes sufficient to flow the holes supplied from the p-type nitride semiconductor layer 310 and the active layer 320, Region can be relatively uniformly recombined.

Therefore, it is possible to exhibit a uniform light distribution in the case where such a current-spreading layer 500 is located in the light-emitting element, and to have an excellent light distribution and light output as compared with the vertical light-emitting element structure shown in Figs. 2 and 3 .

That is, the current density can be uniformly dispersed without causing a current densification phenomenon in the lower portion of the n-type electrode and no non-emission region in the active layer region.

Hereinafter, a method of manufacturing a light emitting device having the above-described structure will be described with reference to FIGS. 6 to 13. FIG.

First, as shown in FIG. 6, an n-type nitride semiconductor layer 330 is grown on a sapphire substrate 110. After the n-type nitride semiconductor layer 330 is formed to have a predetermined thickness, a part of the n-type nitride semiconductor layer 330 is partially insulated using an ion implanting apparatus to form the current diffusion layer 500 To form an insulating layer to be used.

7, a mask 600 is formed using an oxide, a nitride, or a metal through patterning in a part of the n-type nitride semiconductor layer 330, and an ion implantation apparatus Type dopant (ion implantation).

At this time, the n-type dopant included in the n-type nitride semiconductor layer 330 is compensated by the injected p-type dopant, so that the region where the mask 600 is not formed is insulated to form the current diffusion layer 500 .

Thereafter, as shown in FIG. 9, the mask 600 is removed and heat treatment is performed at a temperature of 900 占 폚 or more for crystallization recovery of the current spreading layer 500 and the surface of the n-type nitride semiconductor layer 330 and dopant activation . More specifically, a heat treatment process may be applied in a range of 900 ° C to 1300 ° C. However, in the absence of such a heat treatment process, a similar effect to the heat treatment process may be achieved through the high temperature operation in the MOCVD chamber for semiconductor growth.

11, the active layer 320 and the p-type nitride semiconductor layer (not shown) are grown on the n-type nitride semiconductor layer 330, 310).

Next, as shown in FIG. 12, a p-type electrode 200 is formed on the p-type nitride semiconductor layer 310. The p-type electrode 200 may include a reflective electrode. A conductive substrate 100 may be formed on the p-type electrode 200. The conductive substrate 100 may be formed using a metal.

The sapphire substrate 110 may be separated by a substrate separation method such as a laser lift-off while supporting the semiconductor light emitting device using the conductive substrate 100. In this case, .

When the n-type electrode 400 is formed on the separated surface of the sapphire substrate 110, a vertical light emitting device structure as shown in FIG. 4 is formed.

As shown in Fig. 14, a semiconductor 120 may be used as the conductive substrate 100 instead of a metal. That is, as the conductive substrate 100, the semiconductor 120 in which the contact metal 130 is located on the upper and lower sides may be used.

On the other hand, in the process of forming the current dispersion layer in the n-type nitride semiconductor layer 330, a current dispersion layer can be formed by a method other than the method using the mask 600 pattern shown in FIGS. 7 to 9 have.

That is, after an insulating nitride semiconductor thin film is formed entirely on the n-type nitride semiconductor layer 330, an n-type dopant is formed in a certain region of the insulating nitride semiconductor layer to a certain depth using an ion implantation apparatus, And the manufacturing method thereafter is the same as the above-described example. In this case, the structure of the light emitting device becomes the structure shown in FIG.

In this structure, as shown in the figure, the current dispersion layer 510 made of the insulating nitride semiconductor layer formed on the n-type nitride semiconductor layer 330 is located below the n-type electrode 400, The n-type nitride semiconductor layer 520 formed by ion implantation of the n-type dopant is located around the layer 510.

That is, the current dispersion structure includes a current spreading layer 510 made of an insulating layer located under the n-type electrode 400 and an n-type nitride semiconductor layer 520 disposed around the current spreading layer 510 Lt; / RTI >

16, the electrons supplied to the n-type nitride semiconductor layer 330 in the n-type electrode 400 are separated from the current dispersion layer Type nitride semiconductor layer 520 formed by ion implantation around the n-type nitride semiconductor layer 510, thereby providing a uniform current path.

Therefore, the structure shown in FIG. 4 or the structure shown in FIG. 15 can be selectively considered in consideration of the insulating property and the n-type property of the nitride semiconductor layer by the ion implantation process.

Further, the composite current diffusion layers 530, 540, 550, and 560 shown in FIG. 17 may be formed through the ion implantation process described above and the repetitive operation of forming the n-type nitride semiconductor layer.

That is, two current spreading layers 530 and 560 spaced apart from each other in the vertical direction from the n-type electrode 400 and two current spreading layers 530 and 560 located at the same distance from the n-type electrode 400 and horizontally spaced from each other Layers 540 and 550, and optionally may be located there or more current spreading layers.

By optimizing the path of the electrons supplied from the n-type electrode 400 in consideration of various design factors of the vertical type nitride semiconductor light emitting device, uniform light distribution characteristics of the light emitting device can be maximized.

18, the transparent electrode layer 410 may be positioned between the n-type electrode 400 and the n-type nitride semiconductor layer 330. [ The transparent electrode layer 410 may be formed of a transparent conductive oxide such as ITO or ZnO having excellent electrical conductivity, and the current diffusion effect may be further improved by the transparent electrode layer 410.

That is, the electrons injected through the n-type electrode 400 can be uniformly dispersed through the transparent electrode layer 410 having substantially the same width as the n-type nitride semiconductor layer 330, The effect of current dispersion by the transparent electrode layer 410 can be maximized.

In some cases, as shown in FIG. 19, the current-spreading layer 570 may be placed in contact with the transparent electrode layer 410. The current spreading layer 570 positioned to be in contact with the transparent electrode layer 410 is capable of inducing dispersion of current at a position above the light emitting device structure.

The light emitting device as described above can freely control the current flowing path by controlling the current flow between the n-type electrode and the p-type electrode by applying a current dispersion layer in the vertical type nitride semiconductor light emitting device (LED).

Thus, ultimately, the current dispersion effect of the light emitting device can be maximized, and the light output can be improved through the uniform light distribution of the vertical light emitting device.

The application of such a current-spreading layer allows a wide variety of structures (patterns and depths) to be freely applied by the design elements, making it possible to effectively utilize the active layer region and to maximize light output through effective current path control of the light- You can.

100: conductive substrate 200: p-type electrode
300: semiconductor structure 310: p-type semiconductor layer
320: active layer 330: n- type semiconductor layer
400: n-type electrode 500: current dispersion layer

Claims (15)

A conductive substrate;
A p-type electrode located on the substrate;
A p-type nitride semiconductor layer located on the p-type electrode;
An active layer located on the p-type nitride semiconductor layer;
An n-type nitride semiconductor layer disposed on the active layer;
A current spreading layer located in the n-type nitride semiconductor layer; And
An n-type electrode located on the n-type nitride semiconductor layer;
And a transparent electrode layer which is located between the n-type nitride semiconductor layer and the n-type electrode and covers the n-type nitride semiconductor layer,
The current dispersion layer is provided on the current flow path between the p-type electrode and the n-type electrode, and the plurality of current dispersion layers are formed between the p-type electrode and the n- Wherein the first and second semiconductor light emitting devices are spaced apart from each other. delete The vertical type semiconductor light emitting device according to claim 1, wherein the current dispersion layer is an insulated semiconductor layer. The vertical semiconductor light emitting device of claim 3, wherein the insulated semiconductor layer includes an n-type dopant and a p-type dopant. The vertical semiconductor light emitting device according to claim 1, wherein the thickness of the current spreading layer is 10 nm or more and is equal to or less than the thickness of the n-type nitride semiconductor layer. The vertical type semiconductor light emitting device according to claim 1, wherein an area of the current dispersion layer is larger than an area of the n-type electrode. The vertical semiconductor light emitting device according to claim 1, wherein the transparent electrode layer is formed of a transparent conductive oxide including ITO or ZnO. The vertical type semiconductor light emitting device according to claim 1, wherein the current spreading layer is in contact with the transparent electrode layer. delete delete The vertical-type semiconductor light-emitting device according to claim 1, wherein the plurality of current-spreading layers further include a current-spreading layer disposed between the p-type electrode and the n- . The device according to claim 1, wherein the current-
An insulating layer located under the n-type electrode;
And an n-type nitride semiconductor layer located in a peripheral region of the insulating layer. The vertical semiconductor light emitting device according to claim 1, wherein the conductive substrate is a metal or a semiconductor. The vertical semiconductor light emitting device according to claim 1, wherein the p-type electrode comprises a reflective electrode. The vertical type semiconductor light emitting device according to claim 1, wherein the current dispersion layer is spaced apart from the n-type electrode.

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