WO2017185773A1

WO2017185773A1 - Light-emitting diode and manufacturing method therefor

Info

Publication number: WO2017185773A1
Application number: PCT/CN2016/111668
Authority: WO
Inventors: 林忠宝; 程虎; 林兓兓; 张家宏
Original assignee: 厦门市三安光电科技有限公司
Priority date: 2016-04-25
Filing date: 2016-12-23
Publication date: 2017-11-02
Also published as: CN105702817A; CN105702817B

Abstract

Provided are a light-emitting diode and a manufacturing method therefor, comprising an underlayment (100), performing a cleaning process on a surface of the underlayment (100); growing a buffer layer (200) and an N-type semiconductor layer (300) on the surface of the underlayment (100) in sequence; growing a quantum well layer (400) on a surface of the N-type semiconductor layer (300), wherein the growth of the quantum well layer (400) comprises: the growth of a defect layer (410), a recovered layer (420) and a light-emitting layer (430); and growing a first P-type semiconductor layer (510), an electron blocking layer (520) and a second P-type semiconductor layer (530) on a surface of the quantum well layer (400). Increasing In composition on the premise of improving the quality of the quantum well and meanwhile using the high pressure and lightly doped first P-type layer structure, improve the light-emitting brightness of the light-emitting diode.

Description

Light emitting diode and preparation method thereof

Technical field

The invention belongs to the technical field of semiconductor manufacturing, and in particular relates to a light emitting diode and a preparation method thereof.

Background technique

In recent years, the research of InGaN/GaN multiple quantum well layers as active regions of blue-green light-emitting diodes has become more and more extensive. In the conventional LED epitaxial structure, a buffer layer, an N-type layer, a stress releasing layer, a light-emitting layer and a P-type layer are generally included, and the stress releasing layer can only serve to release the growth stress of the light-emitting layer. The improvement of luminous efficiency is limited.

In order to better solve the influence of the stress existing between the N-type layer and the luminescent layer on the luminous efficiency of the LED device, the multi-quantum well layer structure of the gradation structure is often added in the prior art to increase the luminous efficiency of the LED device. For example, in CN201300008579.1, a low-temperature shallow quantum well layer having a gradient of In doping gradient is disposed under a low temperature multiple quantum well layer, and an aluminum-containing layer is used as a barrier layer, and the amount of aluminum is also gradually changed. However, the epitaxial layer structure of the LED prepared by the method has limited performance in all aspects of the LED chip, and can only partially improve the luminous efficiency, and has little effect on other aspects of the LED chip.

technical problem

Problem solution

Technical solution

In view of the above problems, the present invention provides a light emitting diode and a method for fabricating the same, which can increase the In composition and improve the light emitting brightness of the light emitting diode under the premise of improving the quality of the quantum well.

The technical solution of the present invention is: a method for preparing a light emitting diode, comprising the steps of: providing a substrate, performing a cleaning process on the surface of the substrate; sequentially growing a buffer layer, an N-type semiconductor layer, and a quantum on the surface of the substrate a well layer, a first P-type semiconductor layer, an electron blocking layer and a second P-type semiconductor layer; the step of growing the quantum well layer is specifically: first adjusting the temperature of the reaction chamber to a first temperature T1, and growing by an In/Ga content a defect layer formed by cyclically laminating a C1 InGaN well layer and a GaN barrier layer; subsequently adjusting a reaction chamber temperature to a second temperature T2, and growing an InGaN well layer having an In/Ga content ratio of C2 and a GaN barrier layer cyclically stacked a repair layer; wherein, C2<C1;T2>T1; finally adjusting the temperature of the reaction chamber to a third temperature T3, and growing a light-emitting layer formed by cyclically laminating an InGaN well layer having an In/Ga content ratio of C3 and a GaN barrier layer; After the growth of the quantum well layer is completed, the first P-type doped layer is grown under high pressure conditions, the growth pressure is 350-500 mbar, and the first P-type layer is a low-concentration doped layer, and the doping concentration is 1×. 10 ¹⁷ cm ^-3 to 3 × 10 ¹⁷ cm ^-3 .

Preferably, the first temperature T1 of the defect layer ranges from 700 to 780 ° C; and the In/Ga content ratio of the InGaN well layer is 50% to 80%.

Preferably, the second temperature T2 of the repair layer ranges from 780 to 900 ° C; and the InGaN ratio of the InGaN well layer ranges from 45% to 60%.

Preferably, the third temperature T3 of the light-emitting layer ranges from 650 to 850 ° C; and the In/Ga content ratio of the InGaN well layer is 50% to 60%.

Preferably, the lattice defect density is 5 × 10 ¹⁷ cm ^-2 to 5 × 10 ¹⁸ cm ^-2 .

Preferably, the defect layer has a total thickness of 40 nm to 115 nm, a cycle period of 15 to 25, and a thickness ratio of the well layer to the barrier layer per cycle of 1:2 to 1:5.

Preferably, the repair layer has a total thickness of 150 nm to 200 nm, a cycle period of 2 to 5, and a thickness ratio of the well layer to the barrier layer per cycle of 1:6 to 1:10.

Preferably, the total thickness of the light-emitting layer is 140 nm to 345 nm, the cycle period is 8-15, and the thickness ratio of the well layer to the barrier layer is 1:5.5 to 1:10 per cycle.

Preferably, the defect layer, the repair layer and the light-emitting layer are n-type doped layers.

Preferably, the defect layer and the repair layer have a doping concentration of 1×10 ¹⁸ cm ⁻³ to 5×10 ¹⁸ cm ⁻³ .

Preferably, the light-emitting layer has a doping concentration of 1×10 ¹⁷ cm ⁻³ to 5×10 ¹⁷ cm ⁻³ .

The invention also provides a light emitting diode, which is, in order from bottom to top, a substrate, a buffer layer, an N-type semiconductor layer, a quantum well layer, a first P-type semiconductor layer, an electron blocking layer and a second P-type semiconductor layer, The quantum well layer is composed of a defect layer, a repair layer, and a light-emitting layer;

The defect layer is formed by cyclically laminating an InGaN well layer having an In/Ga content ratio of C1 and a GaN barrier layer;

The repair layer is formed by cyclically laminating an InGaN well layer having an In/Ga content ratio of C2 and a GaN barrier layer, wherein C2<C1;

The light emitting layer is formed by cyclically laminating an InGaN well layer having an In/Ga content ratio of C3 and a GaN barrier layer;

The first P-type doped layer on the surface of the quantum well layer is a low concentration doped layer, and the doping concentration is 1×10 ¹⁷ cm ⁻³ to 3×10 ¹⁷ cm ⁻³ .

Advantageous effects of the invention

Beneficial effect

The invention has at least the following beneficial effects:

In the quantum well structure of the present invention, a defect layer is first formed by using low temperature and high indium gallium content to form a high-density "V"-shaped lattice defect, which better releases stress during subsequent growth, and increases electron injection. Efficiency, providing a basis for the radiation composite of the subsequent luminescent layer;

Then, using a higher growth temperature and a low indium gallium content ratio, a repair layer having excellent crystal quality is obtained, and the non-"V" shaped defect of the defect layer is blocked from extending to the subsequent layer, thereby increasing the antistatic capability of the LED and reducing the leakage phenomenon; And providing an excellent growth interface for the subsequent layers;

Finally, a light-emitting layer is grown on the defect layer and the repair layer structure. Since the defect layer has a high-density "V"-shaped defect extending into the light-emitting layer, a sufficient base point is provided for the recombination of electrons and holes, and holes are added. And the effective combination probability of electrons, improve the external quantum efficiency of the light-emitting diode, and increase the brightness of the light.

[0018] and based on the quantum well structure, the first P-type layer is grown at a high voltage to reduce the content of carbon impurities during the growth process, thereby reducing the activation energy of Mg in the GaN material, increasing the doping efficiency of Mg, and thus the growth process. The medium can reduce the access of the Mg source, improve the lattice quality, and further improve the brightness of the light.

[0019] The light-emitting diode obtained by the invention has a brightness increase of 3% to 6%, and the antistatic ability is improved from a 90% pass rate before the improvement to a pass rate of 98% (the test condition is a human body mode of 4000V).

Brief description of the drawing

DRAWINGS

The drawings are intended to provide a further understanding of the invention, and are intended to be a In addition, the drawing figures are a summary of the description and are not drawn to scale.

1 is a flow chart of a method of a specific embodiment of the present invention.

2 is a schematic view of a light emitting diode according to an embodiment of the present invention.

In the figure: 100. substrate; 200. buffer layer; 210. low temperature buffer layer; 220. high temperature buffer layer; 300. N type semiconductor layer; 400. quantum well layer; 410. defect layer; 420. repair layer; Light-emitting layer; 500. P-type semiconductor layer; 510. First P-type semiconductor layer; 520. Electron blocking layer; 530. Second P-type semiconductor layer.

Invention embodiment

Embodiments of the invention

The specific embodiments of the present invention will be described in detail below with reference to the drawings and embodiments.

Referring to FIG. 1, a light emitting diode is sequentially from bottom to top: a substrate 100, a buffer layer 200, an N-type semiconductor layer 300, a quantum well layer 400, and a P-type semiconductor layer 500, wherein the P-type semiconductor layer 500 includes the first A P-type semiconductor layer 510, an electron blocking layer 520, and a second P-type semiconductor layer 530; the quantum well layer 400 is composed of a defect layer 410, a repair layer 420, and a light-emitting layer 430. The defect layer 410 is formed by cyclically laminating an InGaN well layer having an In/Ga content ratio of 50% to 80% and a GaN barrier layer. The repair layer 420 is formed by cyclically laminating an InGaN well layer having an In/Ga content ratio of 45% to 60% and a GaN barrier layer. The thickness of each layer of the repair layer 420 is greater than the thickness of each period of the defect layer 410, but In/Ga The content ratio C2 is smaller than the In/Ga content ratio C1 of the defect layer 410. The light-emitting layer 430 is formed by cyclically laminating an InGaN well layer having an In/Ga content ratio of 50% to 60% and a GaN barrier layer. A quantum well layer of the surface 400 of the first P-type doped layer 510 is a low concentration impurity layer, a doping concentration of ^{^{1 × 10 17 cm -3 ~ 3}} × 10 17 cm -3.

Referring to Figures 1 and 2, in order to realize the structure of the above light-emitting diode, the present invention provides a method for preparing a light-emitting diode, comprising the following steps:

A substrate 100 is provided to clean the surface of the substrate 100, and the surface of the substrate 100 is usually purged under a hydrogen atmosphere or a mixed atmosphere of hydrogen and nitrogen at 1000 to 1200 ° C to remove oxide impurities on the surface of the substrate 100. .

Then, the chamber temperature, the pressure and the atmosphere are adjusted, the gallium source and the nitrogen source are passed, and the buffer layer 200 is grown. In this embodiment, the buffer layer 200 includes a low temperature buffer layer 210 and a high temperature buffer layer 220; the low temperature buffer layer 210 is mainly followed. The growth provides a nucleation point while reducing the lattice difference between the substrate 100 and subsequent layers, and releasing stress during subsequent deposition to improve crystal quality. The high temperature buffer layer 220 mainly provides an excellent growth interface for the growth of the subsequent N-type semiconductor layer 300, reduces crystal defects, and improves the electrical performance of the light emitting diode.

After the n-type impurity source is introduced into the chamber, the chamber environment is grown to grow the N-type semiconductor layer 300.

Then, adjusting the chamber environment to the conditions required for quantum well growth, the quantum well layer 400 is grown, specifically:

First, the temperature of the reaction chamber is adjusted to a first temperature T1 of 700 to 780 ° C, and an Indium source, a gallium source, a nitrogen source, and an n-type impurity source are introduced, and InGaN having an In/Ga content ratio of C1 of 50% to 80% is grown. The defect layer 410 formed by cyclically laminating the well layer and the GaN barrier layer has a cycle period of 15 to 25 and a total thickness of 150 nm to 200 nm, wherein the ratio of the thickness of the well layer to the barrier layer in each cycle is 1:2 to 1:6; And the growth temperature of the well layer and the barrier layer is the same or different, and the present embodiment preferably grows at the same temperature. The n-type doping concentration in the defect layer 410 is 1 × 10 ¹⁸ cm ^-3 to 5 × 10 ¹⁸ cm ^-3 . The defect layer 410 is formed by using low temperature and high indium gallium content to form a high density "V" shape and a non-"V" shape lattice defect, and the defect density is as high as 5×10 ¹⁷ cm ^-2 to 5×10 ¹⁸ cm. ^-2 , better release of stress during subsequent growth, and because electrons pass through the GaN material layer through the "V" shaped defect, thereby increasing electron injection efficiency and improving light emission brightness.

Subsequently, the reaction chamber temperature is adjusted to a second temperature T2 of 780 to 900 ° C, and a repair layer 420 formed by cyclically laminating an InGaN well layer and a GaN barrier layer having an In/Ga content ratio of 45% to 60% is grown. 2 to 5, the total thickness is 40 nm to 115 nm, wherein the ratio of the thickness of the well layer to the barrier layer in each period is 1:6 to 1:10; and the growth temperature of the well layer and the barrier layer is the same or different, this embodiment It is preferred to grow at different temperatures, and the temperature difference between the barrier layer temperature and the well layer is 80 to 110 °C. The defect layer has a doping concentration of 1 × 10 ¹⁸ cm ^-3 to 5 × 10 ¹⁸ cm ^-3 . The repair layer 420 utilizes an In/Ga content ratio lower than the defect layer and a high growth temperature to lower the In source effectively incorporated into the layer, thereby obtaining excellent crystal quality; meanwhile, the thickness of each layer of the repair layer 420 is greater than The thickness of each period of the defect layer 410, especially the thickness of the barrier layer, thereby better blocking the non-"V" shaped defect in the defect layer 410 from extending to the subsequent layer, increasing the antistatic capability of the LED and reducing the leakage phenomenon; C2<C1, T2>T1 further enhances the crystal quality and provides an excellent growth interface for the subsequent growth layer.

Next, the reaction chamber temperature is adjusted to a third temperature T3 of 650 to 850 ° C, and a light-emitting layer 430 formed by cyclically laminating an InGaN well layer and a GaN barrier layer having an In/Ga content ratio C3 of 50% to 60% is grown. 8 to 15, the total thickness is 135 nm to 345 nm, wherein the ratio of the thickness of the well layer to the barrier layer in each period is 1:5.5 to 1:10; and the growth temperature of the well layer and the barrier layer is the same or different, this embodiment It is preferred to grow at different temperatures, and the temperature difference between the barrier layer temperature and the well layer is 80 to 110 °C. The defect layer is doped with a concentration of ^{^{1 × 10 17 cm -3 ~ 5}} × 10 17 cm -3. Because the light-emitting layer 430 is based on the structure of the defect layer 410 and the repair layer 420, it has a high-density "V"-shaped defect, which provides a base point for the recombination of electrons and holes, increases the probability of recombination, and improves the brightness of the light.

In the present invention, the quantum well structure employs a defect layer 410 having a high density defect in combination with a high crystal quality repair layer 420 to improve the stress release capability while avoiding affecting the crystal quality of the subsequent light emitting layer 430; The extension of the non-V-type defect is broken and the side of the "V"-shaped defect is micro-repaired to make it more effective for subsequent effective recombination of electrons and holes. The long light-emitting layer 430 is then regenerated on the surface of the repair layer 420 to finally form the quantum well layer 400. In the present invention, the repair layer 420 and the light-emitting layer 430 are both thick film structures, most The low thickness is 20 nm and 17 nm, respectively (conventional structures are 15 nm and 13 nm, respectively), and if the thick film structure is used in the conventional quantum well structure, the brightness thereof is remarkably lowered, but the brightness is increased by 3% in accordance with the growth conditions of the present invention. ~5% or so, and the antistatic ability is increased from the previous 90% pass rate to 98% pass rate (test condition is human body mode 4000V).

Finally, the chamber conditions are adjusted, wherein the pressure is 350-450 mbar, and the first P-type semiconductor layer 510 is grown by using high-voltage conditions; and the pressure is changed to a conventional condition to continue growing the electron blocking layer 520 and the second P-type semiconductor layer 530 to form a P-type semiconductor. Layer 500, ultimately forming a light emitting diode. Here, the first P-type semiconductor layer 510 is grown using high-voltage conditions, which reduces the content of carbon impurities during the growth process, thereby reducing the activation energy of Mg in the GaN material, thereby increasing the doping efficiency of Mg, and thus can be reduced during growth. For the introduction of the Mg source, the Mg doping concentration of the present invention is 1 × 10 ¹⁷ cm ^-3 to 3 × 10 ¹⁷ cm ^-3 , which is only 1/5 of the Mg concentration of the conventional first P-type layer, which is extremely large. The crystal quality is improved, the light absorption effect due to the poor crystal lattice quality of the material is reduced, and the luminance of the light is further improved.

It is to be understood that the above-described embodiments are a preferred embodiment of the invention, and the scope of the invention is not limited to the embodiment, and any modifications made in accordance with the invention are within the scope of the invention.

Claims

A method for preparing a light emitting diode includes the following steps:

Providing a substrate for performing a cleaning process on the surface of the substrate;

Forming a buffer layer, an N-type semiconductor layer, a quantum well layer, a first P-type semiconductor layer, an electron blocking layer, and a second P-type semiconductor layer sequentially on the surface of the substrate;

The step of growing the quantum well layer is specifically

First, adjusting the temperature of the reaction chamber to a first temperature T1, and growing a defect layer formed by cyclically laminating an InGaN well layer having an In/Ga content ratio of C1 and a GaN barrier layer;

Subsequently, the reaction chamber temperature is adjusted to a second temperature T2, and a repair layer formed by cyclically laminating an InGaN well layer having an In/Ga content ratio of C2 and a GaN barrier layer is grown; wherein C2<C1; T2>T1;

Finally, the reaction chamber temperature is adjusted to a third temperature T3, and a light-emitting layer formed by cyclically laminating an InGaN well layer having an In/Ga content ratio of C3 and a GaN barrier layer is grown;

After the growth of the quantum well layer is completed, the first P-type doped layer is grown under high pressure conditions, the growth pressure is 350-500 mbar, and the first P-type layer is a low-concentration doped layer, and the doping concentration is 1×. 10 17 cm -3 to 3 × 10 17 cm -3 .
The method for fabricating a light emitting diode according to claim 1, wherein the first temperature T1 of the defect layer ranges from 700 to 780 ° C; and the In/Ga content ratio of the InGaN well layer is 50 %~80%.
The method for preparing a light emitting diode according to claim 1, wherein the second temperature T2 of the repair layer ranges from 780 to 900 ° C; and the In/Ga content ratio of the InGaN well layer is 45 %~60%.
The method for fabricating a light emitting diode according to claim 1, wherein the third temperature T3 of the light emitting layer ranges from 650 to 850 ° C; and the In/Ga content ratio of the InGaN well layer is 50 %~60%.
The method of fabricating a light emitting diode according to claim 1, wherein the defect layer has a defect density of 5 × 10 17 cm -2 to 5 × 10 18 cm -2 .
A method of fabricating a light emitting diode according to claim 1, wherein: The defect layer has a total thickness of 40 nm to 115 nm, a cycle period of 15 to 25, and a thickness ratio of the well layer to the barrier layer per cycle of 1:2 to 1:5.
The method for preparing a light emitting diode according to claim 1, wherein the repair layer has a total thickness of 150 nm to 200 nm, a cycle period of 2 to 5, and a ratio of a well layer to a barrier layer thickness of 1 per cycle. : 6 to 1:10.
The method for fabricating a light emitting diode according to claim 1, wherein the total thickness of the light emitting layer is 140 nm to 345 nm, the cycle period is 8 to 15, and the ratio of the thickness of the well layer to the barrier layer is 1 per cycle. : 5.5 to 1:10.
The method of manufacturing a light emitting diode according to claim 1, wherein the defect layer, the repair layer and the light emitting layer are both n-type doped layers.
A method of fabricating a light emitting diode according to claim 9, wherein the defect layer and the repair layer have a doping concentration of 1 × 10 18 cm -3 to 5 × 10 18 cm -3 .
The method for producing a light emitting diode according to claim 9, wherein: said light emitting layer is doped at a concentration of 1 × 10 17 cm -3 ~ 5 × 10 17 cm -3.
A light emitting diode, from bottom to top, is a substrate, a buffer layer, an N-type semiconductor layer, a quantum well layer, a first P-type semiconductor layer, an electron blocking layer, and a second P-type semiconductor layer, wherein: The quantum well layer is composed of a defect layer, a repair layer and a light-emitting layer;

among them,

The defect layer is formed by cyclically laminating an InGaN well layer having an In/Ga content ratio of C1 and a GaN barrier layer;

The repair layer is formed by cyclically laminating an InGaN well layer having an In/Ga content ratio of C2 and a GaN barrier layer, wherein C2<C1;

The light emitting layer is formed by cyclically laminating an InGaN well layer having an In/Ga content ratio of C3 and a GaN barrier layer;

The first P-type doped layer on the surface of the quantum well layer is a low concentration doped layer, and the doping concentration is 1×10 17 cm −3 to 3×10 17 cm −3 .