A method for cleaning the In on the sidewalls of the V-shaped pits in InGaN-based LEDs

Abstract

The application discloses a method for cleaning In of V-shaped pit sidewall of InGaN-based LED, which is composed of a substrate, an N layer, a preparation layer, a quantum well InGaN / GaN light-emitting layer, and a P layer; the quantum well InGaN / GaN light-emitting layer is divided into a quantum well InGaN layer, a GaN cover layer, and a quantum barrier GaN; the GaN cover layer comprises a platform region and a V-shaped pit region; and the GaN cover layer is divided into two growth stages, that is, a first growth stage for growing the GaN cover layer by inputting a gas without H2, and a second growth stage for cleaning by inputting a gas containing H2. The growth method can clean In in the V-shaped pit sidewall of the quantum well InGaN layer and protect In in the platform region of the quantum well InGaN layer at the same time. After the In in the V-shaped pit sidewall of the quantum well InGaN layer is cleaned, the band gap of the V-shaped pit sidewall is increased, the electron leakage to the V-shaped pit is reduced, and the light-emitting efficiency of the LED is improved.

Description

Technical Field

[0001] This invention relates to the field of semiconductors, and more particularly to a method for cleaning the In on the V-shaped pit sidewalls of InGaN-based LEDs. Background Technology

[0002] GaN materials possess direct wide bandgap, good thermal stability, and chemical stability, making them important for applications in light-emitting diodes, lasers, detectors, and high electron mobility transistors. However, due to the large lattice and thermal mismatches between heteroepitaxial GaN and its substrate (e.g., 17% lattice mismatch and 46% thermal mismatch between Si substrate and GaN), high-density defects exist when growing GaN on Si substrates. These defects easily become nonradiative recombination centers, carrier scattering centers, and leakage current channels in GaN materials, reducing the efficiency and lifetime of GaN-based devices and hindering their further development and application.

[0003] V-shaped pits are a common defect in GaN-based materials. Unlike other types of defects, V-shaped pits play a role in improving the luminous efficiency of LEDs in InGaN / GaN quantum wells. Although the presence of V-shaped pits sacrifices some plateau, the sidewalls of the V-shaped pits are semi-polar surfaces, resulting in a lower polarization charge density at the quantum well interface compared to the plateau quantum well. The potential barrier that needs to be overcome for hole injection from the sidewalls of the V-shaped pits is lower than that for injection from the plateau, making hole injection from the sidewalls easier and further improving luminous efficiency.

[0004] The V-shaped pit sidewalls or V-points are rich in elements such as In. Since the band gap of InN material is smaller than that of GaN material, electrons tend to flow into the V-shaped pit sidewalls or V-points because the band gap of InN or InGaN material is smaller than that of plateau GaN. This leads to electron leakage and reduces the luminous efficiency of LED devices. Summary of the Invention

[0005] The purpose of this invention is to provide a method for cleaning the In of the V-shaped pit sidewalls of InGaN-based LEDs. This method can increase the bandgap of the V-shaped pit sidewalls after cleaning the In, reduce electron leakage into the V-shaped pits, and improve the luminous efficiency of the LEDs.

[0006] A method for cleaning the V-shaped pit sidewalls (In) of an InGaN-based LED, wherein the LED comprises a substrate, an N-layer, a preparation layer, a quantum well InGaN / GaN light-emitting layer, and a P-layer. The quantum well InGaN / GaN light-emitting layer is divided into a quantum well InGaN layer, a GaN capping layer, and a quantum barrier GaN layer. The GaN capping layer is located between the quantum well InGaN layer and the quantum barrier GaN layer. The GaN capping layer includes a platform region and a V-shaped pit region parallel to the substrate, which are disposed at the same location. The method is characterized by the following: the GaN capping layer is grown in two stages, namely: in the first growth stage, a gas without H2 is introduced to grow the GaN capping layer, and in the second growth stage, a gas containing H2 is introduced for cleaning.

[0007] In the first growth stage, the growth temperature T1 of the GaN capping layer is the same as the temperature T0 of the quantum well InGaN layer.

[0008] In the first growth stage, the growth rate of the GaN capping layer V1 is greater than the growth rate of the quantum well InGaN layer V0, and the growth range of V0 is 0.4 A / s ≤ V0 ≤ 1 A / s.

[0009] In the first growth stage, the growth thickness of the GaN capping layer platform is D0, and the growth thickness of the GaN capping layer V-shaped pit sidewall is D1, where D1 ≤ D0.

[0010] Furthermore, the range of D1 is: 0A <D1≤10A。

[0011] In the second growth stage, a gas containing H2 is introduced, and the growth temperature of the GaN capping layer is T2, where T1≤T2≤950℃.

[0012] The flow rate of H2 introduced in the second growth stage is less than 30% of the total gas flow rate in the first growth stage.

[0013] Compared with the prior art, the effective effects of the present invention are as follows:

[0014] This invention provides a method for cleaning the InV-shaped pit sidewalls of InGaN-based LEDs. The GaN capping layer is located between a quantum well InGaN layer and a quantum barrier GaN layer. After growing the quantum well InGaN layer, a GaN capping layer of appropriate thickness is grown. The GaN capping layer is divided into a plateau region and a V-shaped pit region, with different growth thicknesses in the two regions. The GaN capping layer growth consists of two stages: a first growth stage using a gas without H2, and a second growth stage using a gas containing H2 for cleaning. The growth process involves two stages: First, a gas without H2 is introduced to grow a GaN layer at the same temperature as the quantum well InGaN layer. This GaN layer protects the surface of the quantum well InGaN layer from decomposition. The GaN capping layer on the V-shaped pit sidewalls is thinner than the GaN capping layer on the platform. Second, a gas containing H2 is introduced. The H2 cleans the V-shaped pit sidewalls. Due to the thinner GaN capping layer on the V-shaped pit sidewalls, H2 decomposes the In in the V-shaped pit sidewalls of the quantum well InGaN layer, removing the In. However, the platform GaN capping layer is thicker, so H2 does not clean the In in the platform region of the quantum well InGaN layer. This growth method achieves the goal of cleaning the In in the V-shaped pit sidewalls of the quantum well InGaN layer while protecting the In in the platform region. After cleaning the In in the V-shaped pit sidewalls, the bandgap of the V-shaped pit sidewalls increases, reducing electron leakage into the V-shaped pits and improving the LED luminous efficiency. Attached Figure Description

[0015] Figure 1 A schematic diagram of the structure of the quantum well InGaN / GaN light-emitting layer provided in an embodiment of the present invention;

[0016] Figure 2 This is a schematic diagram of the structure after the first growth stage of the GaN capping layer is completed, as provided in an embodiment of the present invention.

[0017] Figure 3 This is a schematic diagram of the structure after the second growth stage of the GaN capping layer is completed, as provided in an embodiment of the present invention. Detailed Implementation

[0018] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the specific embodiments or the prior art are described clearly and completely below. However, those skilled in the art will understand that the embodiments described below are only some embodiments of the present invention, not all embodiments, and are only used to illustrate the present invention, and should not be regarded as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0019] Example 1:

[0020] This invention provides a method for cleaning the V-shaped pit sidewalls (In) of an InGaN-based LED. The LED comprises a substrate, an N-layer, a preparation layer, a quantum well InGaN / GaN light-emitting layer, and a P-layer. The structure of the InGaN / GaN light-emitting layer includes a quantum well InGaN layer 10, a GaN capping layer 20, and a quantum barrier GaN layer 30, which are sequentially stacked from bottom to top and periodically grown. The GaN capping layer 20 is located between the quantum well InGaN layer 10 and the quantum barrier GaN layer 30. The GaN capping layer 20 includes a platform region and a V-shaped pit region parallel to the substrate, both located at the same position. The growth process of the GaN capping layer 20 includes a first growth stage 201 and a second growth stage 202. Please refer to [reference needed]. Figure 1 , Figure 2 as well as Figure 3 The specific steps are as follows:

[0021] TEG source, indium source, ammonia and nitrogen are introduced into MOCVD. The growth temperature of quantum well InGaN layer 10 is 760 degrees, the growth pressure is 50 torr, and the growth rate is 0.2 A / s.

[0022] A first growth stage 201 of GaN capping layer is grown on the surface of quantum well InGaN layer 10. The growth temperature and pressure of the first growth stage 201 of GaN capping layer are the same as those of the upper quantum well InGaN layer 10. The indium source is turned off before growth. The growth rate of the first growth stage 201 of GaN capping layer is 0.4 A / s. The platform growth thickness of the first growth stage 201 of GaN capping layer is 30 Å GaN. The V-shaped pit sidewall growth thickness of the first growth stage 201 of GaN capping layer is 10 AGaN. The structural diagram is shown in Figure 2.

[0023] A second growth stage 202 of GaN capping layer is grown on the surface of the first growth stage 201 of GaN capping layer. The flow rate of H2 is 1 sccm / min, the TEG source is turned off, the growth temperature of the second growth stage 202 of GaN capping layer is 900 degrees, and the cleaning time is 200s. The structural diagram is shown in Figure 3.

[0024] In the second growth stage 202 of the GaN capping layer after H2 cleaning, a quantum barrier GaN layer 30 is grown. The growth temperature of the quantum barrier GaN layer 30 is increased to 950 degrees, the growth rate is 0.15 A / s, and the growth thickness is 130 Å.

[0025] Repeat the steps described above in this embodiment and periodically grow the quantum well InGaN layer 10, the GaN capping layer 20, and the quantum barrier GaN layer 30 in sequence, with a cycle number of 8.

[0026] Example 2:

[0027] This invention provides a method for cleaning the In-type pit sidewalls of an InGaN-based LED. The LED comprises a substrate, an N-layer, a preparation layer, a quantum well InGaN / GaN light-emitting layer, and a P-layer. The structure of the InGaN / GaN light-emitting layer includes a quantum well InGaN layer 10, a GaN capping layer 20, and a quantum barrier GaN layer 30, which are sequentially stacked from bottom to top and periodically grown. The GaN capping layer 20 is located between the quantum well InGaN layer 10 and the quantum barrier GaN layer 30. The GaN capping layer 20 includes a platform region and a V-type pit region parallel to the substrate, both disposed at the same location. Please refer to [reference needed]. Figure 1 The specific steps are as follows;

[0028] TEG source, indium source, ammonia and nitrogen were introduced into MOCVD. The growth temperature of quantum well InGaN layer 10 was 760 degrees, the growth pressure was 50 torr, and the growth rate was 0.2 A / s.

[0029] A GaN capping layer first growth stage 201 is grown on the surface of the quantum well InGaN layer 10. The growth temperature and pressure of the GaN capping layer first growth stage 201 are the same as those of the upper quantum well InGaN layer 10. The indium source is turned off before growth. The growth rate is 1A / s. The platform growth thickness of the GaN capping layer first growth stage 201 is 10A GaN. The V-shaped pit sidewall thickness of the GaN capping layer first growth stage 201 is 3A. The structural diagram is shown in Figure 2.

[0030] A second growth stage 202 of GaN capping layer is grown on the surface of the first growth stage 201 of GaN capping layer. The flow rate of H2 is 1 sccm / min. The TEG source is not turned off. The growth temperature of the second growth stage 202 of GaN capping layer is higher than that of the first growth stage 201 of GaN capping layer. The cleaning is performed at a temperature of 900 degrees Celsius for 200 seconds. The structural diagram is shown in Figure 3.

[0031] In the second growth stage 202 of the GaN capping layer after H2 cleaning, a quantum barrier GaN layer 30 is grown. The growth temperature of the quantum barrier GaN layer 30 is increased to 950 degrees, the growth rate is 0.15 A / s, and the growth thickness is 130 Å.

[0032] Repeat the steps described above in this embodiment and periodically grow the quantum well InGaN layer 10, the GaN capping layer 20, and the quantum barrier GaN layer 30 in sequence, with a cycle number of 8.

[0033] Obviously, the description of the present invention should not be construed as being limited to the above embodiments, but rather includes all possible implementations utilizing the inventive concept.

Claims

1. A method for cleaning the V-shaped pit sidewalls (In) of an InGaN-based LED, the LED comprising a substrate, an N-layer, a preparation layer, a quantum well InGaN / GaN light-emitting layer, and a P-layer, wherein the quantum well InGaN / GaN light-emitting layer is divided into a quantum well InGaN layer, a GaN capping layer, and a quantum barrier GaN layer, the GaN capping layer being located between the quantum well InGaN layer and the quantum barrier GaN layer, and the GaN capping layer including a platform region and a V-shaped pit region parallel to the substrate disposed at the same location, characterized in that: The GaN capping layer is grown in two stages: the first stage introduces a gas without H2 to grow the GaN capping layer, and the second stage introduces a gas containing H2 for cleaning. In the first stage, the growth thickness of the GaN capping layer platform is D0, and the growth thickness of the V-shaped pit sidewall of the GaN capping layer is D1, where D1 < D0. The growth thickness D1 of the V-shaped pit sidewall of the GaN capping layer ranges from 1 to 10 Å. In the second stage, a gas containing H2 is introduced, and the growth temperature T2 of the GaN capping layer in the second stage is greater than or equal to the growth temperature T1 of the GaN capping layer in the first stage.

2. The method for cleaning the In-type pit sidewalls of InGaN-based LEDs according to claim 1, characterized in that: In the first growth stage, the growth temperature T1 of the GaN capping layer is the same as the temperature T0 of the quantum well InGaN layer.

3. The method for cleaning the In-type sidewalls of the V-shaped pits in InGaN-based LEDs according to claim 1, characterized in that: In the first growth stage, the growth rate V1 of the GaN capping layer is greater than the growth rate V0 of the quantum well InGaN layer.

4. The method for cleaning the In-type sidewalls of the V-shaped pits in InGaN-based LEDs according to claim 3, characterized in that: 0.4A / s≤V0≤1A / s.

5. The method for cleaning the In-type pit sidewalls of InGaN-based LEDs according to claim 1, characterized in that: The thickness D0 of the GaN capping layer platform ranges from 5 to 30 Å.

6. The method for cleaning the In-type pit sidewalls of InGaN-based LEDs according to claim 1, characterized in that: 600≤T1≤900℃。 7. The method for cleaning the In-type pit sidewalls of InGaN-based LEDs according to claim 1, characterized in that: The flow rate of H2 introduced during the second growth stage is less than 30% of the total gas flow rate introduced during the first growth stage of the GaN capping layer.

Images