LED Epitaxial Wafer, Preparation Method and Semiconductor Device

Abstract

The present invention discloses a method for preparing an LED epitaxial wafer, comprising: S1, providing a substrate; S2, growing a nitride buffer layer on the substrate; S3, growing an undoped nitride layer on the nitride buffer layer; S4, growing an n-type nitride layer on the undoped nitride layer; S5, growing an insertion layer unit on the n-type nitride layer, the insertion layer unit comprising a pre-nitride insertion layer, an oxide insertion layer, and a post-nitride insertion layer grown in sequence; S6, growing a quantum well light-emitting layer on the insertion layer unit; S7, growing a p-type layer on the quantum well light-emitting layer. The method for preparing the LED epitaxial wafer of the present invention decelerates electrons through the high potential barrier of the oxide insertion layer, buffers the injection of electrons into the light-emitting layer, reduces the recombination of electrons crossing the light-emitting layer with holes in the p-type layer, improves the droop effect under high current, and at the same time, the electron diffusion is more uniform after passing through the oxide insertion layer, improves the uniformity of the electron distribution in the light-emitting layer, increases the light-emitting efficiency, and improves the epitaxial optoelectronic uniformity and consistency.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and particularly to an LED epitaxial wafer, a preparation method thereof, and a semiconductor device. Background Art

[0002] The GaN-based light-emitting diode (LED) is a semiconductor light-emitting device, which has the advantages of long life, low energy consumption, small size, high reliability, etc., and plays an increasingly important role in the fields of large-screen color display, traffic signal lights, and lighting.

[0003] Currently, GaN-based LEDs generally grow an epitaxial layer on a sapphire substrate, which successively includes a low-temperature GaN buffer layer, a high-temperature undoped GaN layer, an n-type doped layer, an InGaN / GaN multi-quantum well (MQW) light-emitting layer, a p-type AlGaN electron blocking layer, and a p-type layer. On the one hand, since the mobility of electrons is faster than that of holes, and the concentration of free electrons is higher than that of holes, it is easy to cause uneven distribution of electrons and holes in the MQW. The holes are concentrated in the MQW closer to the p-type layer and gradually attenuate in the n-type direction, which is not conducive to the recombination of electrons and holes. On the other hand, due to the high electron concentration and fast migration, electrons are prone to overflow into the p-type layer and recombine with the ionized holes in the p-type layer, reducing the ionization efficiency of holes, generating non-radiative recombination, reducing the injection efficiency of holes, and causing the efficiency droop effect, which is more serious under high-current working conditions.

[0004] Currently, generally, the Al composition of the p-type AlGaN electron blocking layer is increased to block the overflow of electrons between the active region and the hole supply layer. The high Al composition can limit the overflow of some electrons to the p-type layer. However, as the Al composition of AlGaN increases, the ionization energy of Mg increases rapidly and the crystal quality will decrease significantly, resulting in a sharp decrease in the hole ionization efficiency and concentration, and then causing a decrease in brightness and efficiency. The internal polarization field at the interface between the last quantum barrier of the light-emitting layer and the p-type AlGaN electron blocking layer and at the interface between the electron blocking layer and the p-type layer. The electron blocking layer with a high Al composition will cause severe band bending, and a peak appears at the interface, preventing holes from effectively injecting into the active region. In addition, under the condition of high-current injection, a large number of electrons in the AlGaN EBL structure with a high Al composition will still overflow into the p-type layer, causing problems such as efficiency droop effect, aging, and light decay. At the same time, as the Al composition increases, the crystal quality of the p-type AlGaN electron blocking layer decreases, and dislocations are amplified in the p-type layer to form a leakage channel, resulting in an increase in LED leakage and poor electrostatic resistance, and a reduction in lifespan. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a preparation method of an LED epitaxial wafer that can improve the droop effect under high current and increase the light-emitting efficiency.

[0006] To solve the above problems, the present invention provides a method for preparing an LED epitaxial wafer, and the method for preparing the LED epitaxial wafer includes the following steps:

[0007] S1. Provide a substrate;

[0008] S2. Grow a nitride buffer layer on the substrate;

[0009] S3. Grow an undoped nitride layer on the nitride buffer layer;

[0010] S4. Grow an n-type nitride layer on the undoped nitride layer;

[0011] S5. Grow an insertion layer unit on the n-type nitride layer, and the insertion layer unit includes a pre-nitride insertion layer, an oxide insertion layer, and a post-nitride insertion layer grown in sequence;

[0012] S6. Grow a quantum well light-emitting layer on the insertion layer unit;

[0013] S7. Grow a p-type layer on the quantum well light-emitting layer.

[0014] As a further improvement of the present invention, in step S5, the oxide insertion layer is grown by the following method:

[0015] On the pre-nitride insertion layer, grow the oxide insertion layer using an oxygen-containing MO source; then turn off the oxygen-containing MO source, raise the temperature and anneal to obtain the oxide insertion layer.

[0016] As a further improvement of the present invention, the oxygen-containing MO source is one or two of trimethylgallium oxide and triethylgallium oxide.

[0017] As a further improvement of the present invention, the thickness of the post-nitride insertion layer is greater than that of the pre-nitride insertion layer.

[0018] As a further improvement of the present invention, the oxide insertion layer is Ga 2 O 3 .

[0019] As a further improvement of the present invention, the thickness of the oxide insertion layer is 1-10 nm.

[0020] As a further improvement of the present invention, the pre-nitride insertion layer is GaN, AlGaN or InGaN.

[0021] As a further improvement of the present invention, the post-nitride insertion layer is GaN, AlGaN or InGaN.

[0022] As a further improvement of the present invention, the thickness of the post-nitride is 20-200 nm.

[0023] The present invention also provides an LED epitaxial wafer, which is prepared by using the preparation method of the LED epitaxial wafer described in any one of the above.

[0024] The present invention also provides a semiconductor device, including the above-mentioned LED epitaxial wafer.

[0025] Advantages of the present invention:

[0026] In the preparation method of the LED epitaxial wafer of the present invention, by setting the insertion layer unit, wherein the high potential barrier of the oxide insertion layer can decelerate electrons, buffer the injection of electrons into the light-emitting layer, reduce the recombination of electrons with holes in the p-type layer across the light-emitting layer, improve the droop effect under high current, and at the same time, the electron diffusion is more uniform after passing through the oxide insertion layer, improve the uniformity of the electron distribution in the light-emitting layer, improve the luminous efficiency, and improve the epitaxial optoelectronic uniformity and consistency, which meets the requirements of high uniformity for Micro-LED.

[0027] Among them, the front nitride insertion layer is used to achieve lattice matching between the oxide insertion layer and the n-type nitride layer, and the rear nitride insertion layer is used to achieve lattice matching between the oxide insertion layer and the quantum well light-emitting layer, reducing the stress of the quantum well light-emitting layer. At the same time, by controlling the growth process of the front nitride insertion layer and the rear nitride insertion layer, the V defects in the quantum well light-emitting layer can be modulated to play a role beneficial to light emission.

[0028] The above description is only an overview of the technical solution of the present invention. In order to be able to understand the technical means of the present invention more clearly, it can be implemented according to the content of the specification. And in order to make the above and other purposes, features and advantages of the present invention more obvious and understandable, the following specific preferred embodiments are given, and in conjunction with the drawings, the details are described as follows. Description of the Drawings

[0029] Figure 1 It is a structural diagram of the LED epitaxial wafer in the embodiment of the present invention.

[0030] Marking Explanation:

[0031] 10. Substrate; 20. GaN buffer layer; 30. Undoped GaN layer; 40. nGaN layer; 51. Front GaN insertion layer; 52. Ga 2 O 3 Insertion layer; 53. Rear GaN insertion layer; 60. InGaN / GaN multi-quantum well light-emitting layer; 71. First pGaN layer; 72. Second pGaN layer; Detailed Embodiments

[0032] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, so that those skilled in the art can better understand the present invention and be able to implement it, but the embodiments cited do not limit the present invention.

[0033] Embodiment 1

[0034] This embodiment discloses a method for preparing an LED epitaxial wafer for preparing an LED epitaxial wafer as shown in Figure 1 The method for preparing the LED epitaxial wafer includes the following steps:

[0035] S1. Provide a substrate 10;

[0036] S2. On the substrate 10, at a temperature of 540 °C and a growth pressure of 300 torr, grow a 25-nm GaN buffer layer 20. The Ga source required for growth is a TMG source, and the growth atmosphere is an H 2 atmosphere;

[0037] S3. On the GaN buffer layer 20, at a temperature of 1080 °C and a growth pressure of 200 torr, grow a 3-μm undoped GaN layer 30. The required Ga source for growth is a TMG source, and the growth atmosphere is an H 2 atmosphere;

[0038] S4. On the undoped GaN layer 30, at a temperature of 1060 °C and a growth pressure of 200 torr, grow a 3-μm nGaN layer 40. The doping concentration of Si is 8×10 18 cm -3 The required Ga source for growth is a TMG source, and the growth atmosphere is an H 2 atmosphere;

[0039] S5. On the nGaN 40 layer, grow an insertion layer unit, including:

[0040] S51. At a temperature of 760 °C and a growth pressure of 250 torr, grow a 20-nm pre-GaN insertion layer 51. The required Ga source for growth is a TMG source, and the growth atmosphere is an H 2 atmosphere;

[0041] S52. At a temperature of 620 °C and a growth pressure of 250 torr, switch to an oxygen-containing TMG source and grow a Ga 2 O 3 insertion layer 52. Turn off the oxygen-containing TMG source and raise the temperature to 720 °C for annealing to obtain a 1-nm-thick Ga 2 O 3 insertion layer 52. The growth atmosphere is an N 2 atmosphere;

[0042] S53. At a temperature of 760 °C and a growth pressure of 250 torr, a 100-nm post-GaN insertion layer 53 is grown. The Ga source required for growth is a TMG source, and the growth atmosphere is H 2 atmosphere;

[0043] S6. On the post-GaN insertion layer 53, an InGaN / GaN multiple quantum well light-emitting layer 60 is grown at a temperature of 750 °C and a growth pressure of 250 torr. It is a periodically repeated and alternately grown InGaN quantum well layer and GaN quantum barrier layer. The repetition period of the InGaN / GaN multiple quantum well light-emitting layer 60 is 9. The growth temperature of the InGaN quantum well layer is 750 °C, and the thickness is 3 nm. The growth temperature of the GaN quantum barrier layer is 850 °C, and the thickness is 12 nm. In other embodiments of the present invention, the repetition period of the InGaN / GaN multiple quantum well light-emitting layer 60 can be set as required, and specific values are not limited.

[0044] S71. On the InGaN / GaN multiple quantum well light-emitting layer 60, a first p-GaN layer 71 with a thickness of 40 nm is grown at a temperature of 770 °C and a growth pressure of 200 torr. The Mg doping concentration is 5×10 19 cm -3 , the Ga source required for growth is a TMG source, and the Mg source is Cp 2 Mg, and the growth atmosphere is H 2 atmosphere;

[0045] S72. On the first p-GaN layer 71, a 150-nm second p-GaN layer 72 is grown at a temperature of 930 °C and a growth pressure of 200 torr. The Mg doping concentration is 5×10 19 cm -3 , the Ga source required for growth is a TMG source, and the Mg source is Cp 2 Mg, and the growth atmosphere is switched to H 2 atmosphere.

[0046] In this embodiment, the first p-GaN layer 71 and the second p-GaN layer 72 constitute the p-type layer. The thickness, growth temperature and other parameters of the first p-GaN layer 71 and the second p-GaN layer 72 can be set as required,

[0047] wherein, the first p-GaN layer 71 is used to protect the InGaN / GaN multiple quantum well light-emitting layer 60. In another embodiment of the present invention, the first p-GaN layer 71 can be omitted, that is, the second p-GaN layer 72 is directly grown on the InGaN / GaN multiple quantum well light-emitting layer 60.

[0048] In the present invention, Ga 2 O 3The high barrier of the insertion layer 52 can decelerate electrons, buffer the injection of electrons into the light-emitting layer, reduce the recombination of electrons with holes in the p-type layer across the light-emitting layer, improve the droop effect under high current, and at the same time pass through Ga 2 O 3 The electron diffusion of the insertion layer 52 is more uniform, improving the uniformity of the electron distribution in the light-emitting layer, increasing the light-emitting efficiency, improving the epitaxial optoelectronic uniformity and consistency, and meeting the requirements of high uniformity for Micro-LEDs.

[0049] The front nitride insertion layer is used to achieve lattice matching between the oxide insertion layer and the n-type nitride layer, and the rear nitride insertion layer is used to achieve lattice matching between the oxide insertion layer and the quantum well light-emitting layer, reducing the stress of the quantum well light-emitting layer. At the same time, by controlling the growth process of the front nitride insertion layer and the rear nitride insertion layer, the V defects in the quantum well light-emitting layer can play a role beneficial to light emission.

[0050] Among them, V defects are a characteristic defect in the GaN-based material system. On the one hand, retaining an appropriate amount of V defects in the InGaN / GaN quantum well light-emitting layer is beneficial to using the barrier effect at the V defects to block the leakage of electrons, confine the electron-hole pairs to the defect-free region for recombination and light emission, and is beneficial to the injection of holes into the quantum wells farther from the p-type layer, increasing the recombination efficiency of carriers in the quantum wells. On the other hand, V defects are also non-radiative recombination centers, which can reduce the radiative recombination light emission of carriers, reduce the effective light-emitting area at the same time, and thus reduce the light-emitting efficiency. Therefore, there are two competing mechanisms for V defects in the quantum well light-emitting layer.

[0051] Among them, when growing the oxide insertion layer, by switching the oxygen-containing MO source to provide the O source, there is no need to additionally increase the O source pipeline. After flowing out of the source bottle, the oxygen-containing MO source can share the pipeline with other MO sources before entering the reaction chamber.

[0052] Among them, Ga 2 O 3 The growth temperature of the insertion layer 52 is lower than that of the front GaN insertion layer 51 and the rear GaN insertion layer 53, which can prevent the diffusion of O atoms to the front-end epitaxial layer, reduce the growth quality, form a leakage channel, and reduce the performance such as ESD.

[0053] Among them, the rear GaN insertion layer 53 is set relatively thicker than the front GaN insertion layer 51, which can prevent the oxygen participating in the reaction chamber from diffusing into the light-emitting layer, affecting the growth quality of the light-emitting layer, reducing the light-emitting efficiency, and having a relatively low growth temperature to prevent the diffusion of O atoms to the front-end epitaxial layer, reduce the growth quality, form a leakage channel, and reduce the performance such as ESD.

[0054] Example Two

[0055] This example discloses a method for preparing an LED epitaxial wafer for preparing such asFigure 1 The LED epitaxial wafer shown, the preparation method of the LED epitaxial wafer includes the following steps:

[0056] S1. Provide a substrate 10;

[0057] S2. On the substrate 10, under the conditions of a temperature of 540 °C and a growth pressure of 300 torr, grow a 25-nm GaN buffer layer 20. The Ga source required for growth is a TMG source, and the growth atmosphere is H 2 atmosphere;

[0058] S3. On the GaN buffer layer 20, under the conditions of a temperature of 1080 °C and a growth pressure of 200 torr, grow a 3-μm undoped GaN layer 30. The required Ga source for growth is a TMG source, and the growth atmosphere is H 2 atmosphere;

[0059] S4. On the undoped GaN layer 30, under the conditions of a temperature of 1060 °C and a growth pressure of 200 torr, grow a 3-μm nGaN layer 40. The doping concentration of Si is 8×10 18 cm -3 , the required Ga source for growth is a TMG source, and the growth atmosphere is H 2 atmosphere;

[0060] S5. On the nGaN 40 layer, grow an insertion layer unit; including:

[0061] S51. Under the conditions of a temperature of 760 °C and a growth pressure of 250 torr, grow a 20-nm pre-GaN insertion layer 51. The required Ga source for growth is a TMG source, and the growth atmosphere is H 2 atmosphere;

[0062] S52. Under the conditions of a temperature of 620 °C and a growth pressure of 250 torr, switch to an oxygen-containing TMG source and grow a Ga 2 O 3 insertion layer 52. Turn off the oxygen-containing TMG source and raise the temperature to 720 °C for annealing to obtain a 5-nm-thick Ga 2 O 3 insertion layer 52. The growth atmosphere is N 2 atmosphere;

[0063] S53. Under the conditions of a temperature of 760 °C and a growth pressure of 250 torr, grow a 100-nm post-GaN insertion layer 53. The required Ga source for growth is a TMG source, and the growth atmosphere is H 2 atmosphere;

[0064] S6. On the post - GaN insertion layer 53, under the conditions of a temperature of 750 °C and a growth pressure of 250 torr, grow an InGaN / GaN multi - quantum well light - emitting layer 60, which is a periodically repeated and alternately grown InGaN quantum well layer and GaN quantum barrier layer. The repetition period of the InGaN / GaN multi - quantum well light - emitting layer 60 is 9. The growth temperature of the InGaN quantum well layer is 750 °C and its thickness is 3 nm. The growth temperature of the GaN quantum barrier layer is 850 °C and its thickness is 12 nm;

[0065] S71. On the InGaN / GaN multi - quantum well light - emitting layer 60, under the conditions of a temperature of 770 °C and a growth pressure of 200 torr, grow a first p - GaN layer 71 with a thickness of 40 nm. The Mg doping concentration is 5×10 19 cm -3 . The Ga source required for growth is TMG source, and the Mg source is Cp 2 Mg. The growth atmosphere is H 2 atmosphere;

[0066] S72. On the first p - GaN layer 71, under the conditions of a temperature of 930 °C and a growth pressure of 200 torr, grow a second p - GaN layer 72 with a thickness of 150 nm. The Mg doping concentration is 5×10 19 cm -3 . The Ga source required for growth is TMG source, and the Mg source is Cp 2 Mg. The growth atmosphere is switched to H 2 atmosphere.

[0067] Example 3

[0068] This example discloses a method for preparing an LED epitaxial wafer for preparing an LED epitaxial wafer as shown in Figure 1 . The method for preparing the LED epitaxial wafer includes the following steps:

[0069] S1. Provide a substrate 10;

[0070] S2. On the substrate 10, under the conditions of a temperature of 540 °C and a growth pressure of 300 torr, grow a GaN buffer layer 20 with a thickness of 25 nm. The Ga source required for growth is TMG source, and the growth atmosphere is H 2 atmosphere;

[0071] S3. On the GaN buffer layer 20, under the conditions of a temperature of 1080 °C and a growth pressure of 200 torr, grow an undoped GaN layer 30 with a thickness of 3 μm. The required Ga source is TMG source, and the growth atmosphere is H 2 atmosphere;

[0072] S4. On the undoped GaN layer 30, grow a 3-μm nGaN layer 40 at a temperature of 1060 °C and a growth pressure of 200 torr, with a Si doping concentration of 8×10 18 cm -3 , where the Ga source required for growth is the TMG source and the growth atmosphere is an H 2 atmosphere;

[0073] S5. On the nGaN 40 layer, grow an insertion layer unit, including:

[0074] S51. Grow a 20-nm pre-GaN insertion layer 51 at a temperature of 760 °C and a growth pressure of 250 torr, where the Ga source required for growth is the TMG source and the growth atmosphere is an H 2 atmosphere;

[0075] S52. At a temperature of 620 °C and a growth pressure of 250 torr, switch to an oxygen-containing TMG source and grow a Ga 2 O 3 insertion layer 52. Turn off the oxygen-containing TMG source and anneal by raising the temperature to 720 °C to obtain a 10-nm-thick Ga 2 O 3 insertion layer 52, and the growth atmosphere is an N 2 atmosphere;

[0076] S53. Grow a 100-nm post-GaN insertion layer 53 at a temperature of 760 °C and a growth pressure of 250 torr, where the Ga source required for growth is the TMG source and the growth atmosphere is an H 2 atmosphere;

[0077] S6. On the post-GaN insertion layer 53, grow an InGaN / GaN multiple quantum well light-emitting layer 60 at a temperature of 750 °C and a growth pressure of 250 torr. The InGaN / GaN multiple quantum well light-emitting layer 60 is a periodically repeated alternating growth of InGaN quantum well layers and GaN quantum barrier layers. The repetition period of the InGaN / GaN multiple quantum well light-emitting layer 60 is 9. The growth temperature of the InGaN quantum well layer is 750 °C and the thickness is 3 nm. The growth temperature of the GaN quantum barrier layer is 850 °C and the thickness is 12 nm;

[0078] S71. On the InGaN / GaN multiple quantum well light-emitting layer 60, grow a first pGaN layer 71 with a thickness of 40 nm at a temperature of 770 °C and a growth pressure of 200 torr, with an Mg doping concentration of 5×10 19 cm -3 , where the Ga source required for growth is the TMG source and the Mg source is Cp 2 Mg, and the growth atmosphere is an H 2 atmosphere;

[0079] S72. On the first pGaN layer 71, a second pGaN layer 72 with a thickness of 150 nm is grown under the conditions of a temperature of 930 °C and a growth pressure of 200 torr. The Mg doping concentration is 5×10 19 cm -3 , and the Ga source required for growth is the TMG source, and the Mg source is Cp 2 Mg. The growth atmosphere is switched to H 2 atmosphere.

[0080] Example 4

[0081] This example discloses a method for preparing an LED epitaxial wafer for preparing an LED epitaxial wafer as shown in Figure 1 . The method for preparing the LED epitaxial wafer includes the following steps:

[0082] S1. Provide a substrate 10;

[0083] S2. On the substrate 10, a GaN buffer layer 20 with a thickness of 25 nm is grown under the conditions of a temperature of 540 °C and a growth pressure of 300 torr. The Ga source required for growth is the TMG source, and the growth atmosphere is H 2 atmosphere;

[0084] S3. On the GaN buffer layer 20, an undoped GaN layer 30 with a thickness of 3 μm is grown under the conditions of a temperature of 1080 °C and a growth pressure of 200 torr. The required Ga source is the TMG source, and the growth atmosphere is H 2 atmosphere;

[0085] S4. On the undoped GaN layer 30, an nGaN layer 40 with a thickness of 3 μm is grown under the conditions of a temperature of 1060 °C and a growth pressure of 200 torr. The doping concentration of Si is 8×10 18 cm -3 , and the Ga source required for growth is the TMG source, and the growth atmosphere is H 2 atmosphere;

[0086] S5. On the nGaN 40 layer, an insertion layer unit is grown, including:

[0087] S51. At a temperature of 740 °C and a growth pressure of 250 torr, a pre - GaN insertion layer 51 with a thickness of 20 nm is grown. The Ga source required for growth is the TMG source, and the growth atmosphere is H 2 atmosphere;

[0088] S52. At a temperature of 620 °C and a growth pressure of 250 torr, the oxygen - containing TMG source is switched, and Ga 2 O 3 insertion layer 52 is grown. The oxygen - containing TMG source is turned off, and the temperature is raised to 720 °C for annealing to obtain a Ga 2 O3 Insert layer 52, with the growth atmosphere being N 2 atmosphere;

[0089] S53. At a temperature of 760 °C and a growth pressure of 250 torr, grow a 100-nm post-GaN insert layer 53. The Ga source required for growth is the TMG source, and the growth atmosphere is H 2 atmosphere;

[0090] S6. On the post-GaN insert layer 53, at a temperature of 750 °C and a growth pressure of 250 torr, grow an InGaN / GaN multi-quantum well light-emitting layer 60, which is a periodically repeated and alternately grown InGaN quantum well layer and GaN quantum barrier layer. The repetition period of the InGaN / GaN multi-quantum well light-emitting layer 60 is 9. The growth temperature of the InGaN quantum well layer is 750 °C, and the thickness is 3 nm. The growth temperature of the GaN quantum barrier layer is 850 °C, and the thickness is 12 nm;

[0091] S71. On the InGaN / GaN multi-quantum well light-emitting layer 60, at a temperature of 770 °C and a growth pressure of 200 torr, grow a first p-GaN layer 71 with a thickness of 40 nm. The Mg doping concentration is 5×10 19 cm -3 , and the Ga source required for growth is the TMG source, and the Mg source is Cp 2 Mg, and the growth atmosphere is H 2 atmosphere;

[0092] S72. On the first p-GaN layer 71, at a temperature of 930 °C and a growth pressure of 200 torr, grow a 150-nm second p-GaN layer 72. The Mg doping concentration is 5×10 19 cm -3 , and the Ga source required for growth is the TMG source, and the Mg source is Cp 2 Mg, and the growth atmosphere is switched to H 2 atmosphere.

[0093] Example 5

[0094] This example discloses a method for preparing an LED epitaxial wafer for preparing an LED epitaxial wafer as shown in Figure 1 . The method for preparing the LED epitaxial wafer includes the following steps:

[0095] S1. Provide a substrate 10;

[0096] S2. On the substrate 10, at a temperature of 540 °C and a growth pressure of 300 torr, grow a 25-nm GaN buffer layer 20. The Ga source required for growth is the TMG source, and the growth atmosphere is H 2 atmosphere;

[0097] S3. On the GaN buffer layer 20, a 3-μm undoped GaN layer 30 is grown at a temperature of 1080 °C and a growth pressure of 200 torr. The Ga source required is the TMG source, and the growth atmosphere is H 2 atmosphere;

[0098] S4. On the undoped GaN layer 30, a 3-μm nGaN layer 40 is grown at a temperature of 1060 °C and a growth pressure of 200 torr. The doping concentration of Si is 8×10 18 cm -3 , and the Ga source required for growth is the TMG source, and the growth atmosphere is H 2 atmosphere;

[0099] S5. On the nGaN 40 layer, an insertion layer unit is grown, including:

[0100] S51. At a temperature of 760 °C and a growth pressure of 250 torr, a 40-nm pre-GaN insertion layer 51 is grown. The Ga source required for growth is the TMG source, and the growth atmosphere is H 2 atmosphere;

[0101] S52. At a temperature of 620 °C and a growth pressure of 250 torr, the oxygen-containing TMG source is switched to grow the Ga 2 O 3 insertion layer 52. The oxygen-containing TMG source is turned off, and the temperature is raised to 720 °C for annealing to obtain a 1-nm-thick Ga 2 O 3 insertion layer 52. The growth atmosphere is N 2 atmosphere;

[0102] S53. At a temperature of 760 °C and a growth pressure of 250 torr, a 160-nm post-GaN insertion layer 53 is grown. The Ga source required for growth is the TMG source, and the growth atmosphere is H 2 atmosphere;

[0103] S6. On the post-GaN insertion layer 53, an InGaN / GaN multiple quantum well light-emitting layer 60 is grown at a temperature of 750 °C and a growth pressure of 250 torr. It is a periodically repeated and alternately grown InGaN quantum well layer and GaN quantum barrier layer. The repetition period of the InGaN / GaN multiple quantum well light-emitting layer 60 is 9. The growth temperature of the InGaN quantum well layer is 750 °C, and the thickness is 3 nm. The growth temperature of the GaN quantum barrier layer is 850 °C, and the thickness is 12 nm;

[0104] S71. On the InGaN / GaN multiple quantum well light-emitting layer 60, a first pGaN layer 71 with a thickness of 40 nm is grown at a temperature of 770 °C and a growth pressure of 200 torr. The Mg doping concentration is 5×1019 cm -3 The Ga source required for growth is the TMG source, and the Mg source is Cp 2 Mg, and the growth atmosphere is H 2 atmosphere;

[0105] S72. On the first pGaN layer 71, at a temperature of 930 °C and a growth pressure of 200 torr, a second pGaN layer 72 with a thickness of 150 nm is grown, and the Mg doping concentration is 5×10 19 cm -3 The Ga source required for growth is the TMG source, and the Mg source is Cp 2 Mg, and the growth atmosphere is switched to H 2 atmosphere.

[0106] Example 6

[0107] As Figure 1 shown, this example discloses an LED epitaxial wafer, which is prepared by using the preparation method of the LED epitaxial wafer described in any one of Examples 1 to 5, and includes a substrate 10, and a GaN buffer layer 20, an undoped GaN layer 30, an nGaN layer 40, a front GaN insertion layer 51, Ga 2 O 3 insertion layer 52, a rear GaN insertion layer 53, an InGaN / GaN multiple quantum well light-emitting layer 60, a first pGaN layer 71, and a second pGaN layer 72 grown in sequence on the substrate 10.

[0108] Example 7

[0109] This example discloses a semiconductor device, including the LED epitaxial wafer in Example 6.

[0110] Comparative Example 1

[0111] This comparative example discloses a preparation method of an LED epitaxial wafer, and the preparation method of the LED epitaxial wafer includes the following steps:

[0112] S1. Provide a substrate;

[0113] S2. On the substrate, at a temperature of 540 °C and a growth pressure of 300 torr, a GaN buffer layer with a thickness of 25 nm is grown. The Ga source required for growth is the TMG source, and the growth atmosphere is H 2 atmosphere;

[0114] S3. On the GaN buffer layer, at a temperature of 1080 °C and a growth pressure of 200 torr, an undoped GaN layer with a thickness of 3 μm is grown. The required Ga source is the TMG source, and the growth atmosphere is H 2 atmosphere;

[0115] S4. On the undoped GaN layer, a 3-μm nGaN layer is grown at a temperature of 1060 °C and a growth pressure of 200 torr, with a Si doping concentration of 8×10 18 cm -3 , and the Ga source required for growth is the TMG source, and the growth atmosphere is H 2 atmosphere;

[0116] S5. On the nGaN layer, a 120-nm GaN insertion layer is grown at a temperature of 760 °C and a growth pressure of 250 torr, and the Ga source required for growth is the TMG source, and the growth atmosphere is H 2 atmosphere;

[0117] S6. On the GaN insertion layer, an InGaN / GaN multiple quantum well light-emitting layer is grown at a temperature of 750 °C and a growth pressure of 250 torr. It is a periodically repeated and alternately grown InGaN quantum well layer and GaN quantum barrier layer. The repetition period of the InGaN / GaN multiple quantum well light-emitting layer is 9. The growth temperature of the InGaN quantum well layer is 750 °C, and the thickness is 3 nm. The growth temperature of the GaN quantum barrier layer is 850 °C, and the thickness is 12 nm.

[0118] S71. On the InGaN / GaN multiple quantum well light-emitting layer, a 40-nm-thick first pGaN layer is grown at a temperature of 770 °C and a growth pressure of 200 torr, with a Mg doping concentration of 5×10 19 cm -3 , and the Ga source required for growth is the TMG source, and the Mg source is Cp 2 Mg, and the growth atmosphere is H 2 atmosphere;

[0119] S72. On the first pGaN layer, a 150-nm-thick second pGaN layer is grown at a temperature of 930 °C and a growth pressure of 200 torr, with a Mg doping concentration of 5×10 19 cm -3 , and the Ga source required for growth is the TMG source, and the Mg source is Cp 2 Mg, and the growth atmosphere is switched to H 2 atmosphere.

[0120] Comparative Example 2

[0121] This comparative example discloses a method for preparing an LED epitaxial wafer, and the method for preparing the LED epitaxial wafer includes the following steps:

[0122] S1. Provide a substrate;

[0123] S2. On the substrate, a 25-nm GaN buffer layer is grown at a temperature of 540 °C and a growth pressure of 300 torr. The Ga source required for growth is the TMG source, and the growth atmosphere is H 2 atmosphere;

[0124] S3. On the GaN buffer layer, a 3-μm undoped GaN layer is grown at a temperature of 1080 °C and a growth pressure of 200 torr. The required Ga source is the TMG source, and the growth atmosphere is H 2 atmosphere;

[0125] S4. On the undoped GaN layer, a 3-μm nGaN layer is grown at a temperature of 1060 °C and a growth pressure of 200 torr. The doping concentration of Si is 8×10 18 cm -3 , and the required Ga source for growth is the TMG source, and the growth atmosphere is H 2 atmosphere;

[0126] S5. On the nGaN layer, an InGaN / GaN multiple quantum well light-emitting layer is grown at a temperature of 750 °C and a growth pressure of 250 torr. It is a periodically repeated and alternately grown InGaN quantum well layer and GaN quantum barrier layer. The repetition period of the InGaN / GaN multiple quantum well light-emitting layer is 9. The growth temperature of the InGaN quantum well layer is 750 °C, and the thickness is 3 nm. The growth temperature of the GaN quantum barrier layer is 850 °C, and the thickness is 12 nm;

[0127] S6. On the InGaN / GaN multiple quantum well light-emitting layer, a first pGaN layer with a thickness of 40 nm is grown at a temperature of 770 °C and a growth pressure of 200 torr. The Mg doping concentration is 5×10 19 cm -3 , and the required Ga source for growth is the TMG source, and the Mg source is Cp 2 Mg, and the growth atmosphere is H 2 atmosphere;

[0128] S7. On the first pGaN layer, a pAlGaN layer with a thickness of 25 nm is grown at a temperature of 950 °C and a growth pressure of 100 torr. The Mg doping concentration is 5×10 19 cm -3 , and the required Ga source for growth is the TMG source, and the Mg source is Cp 2 Mg, and the growth atmosphere is H 2 atmosphere;

[0129] S8. On the pAlGaN layer, a second pGaN layer with a thickness of 150 nm is grown at a temperature of 930 °C and a growth pressure of 200 torr. The Mg doping concentration is 5×10 19 cm -3, the Ga source required for growth is the TMG source, and the Mg source is Cp 2 Mg, and the growth atmosphere is switched to H 2 atmosphere.

[0130] This comparative example is the preparation method of the existing LED epitaxial wafer mentioned in the background art.

[0131] Comparative Example 3

[0132] This comparative example discloses a method for preparing an LED epitaxial wafer, and the method for preparing the LED epitaxial wafer includes the following steps:

[0133] S1. Provide a substrate;

[0134] S2. On the substrate, at a temperature of 540 °C and a growth pressure of 300 torr, grow a 25-nm GaN buffer layer. The Ga source required for growth is the TMG source, and the growth atmosphere is H 2 atmosphere;

[0135] S3. On the GaN buffer layer, at a temperature of 1080 °C and a growth pressure of 200 torr, grow a 3-μm undoped GaN layer. The required Ga source is the TMG source, and the growth atmosphere is H 2 atmosphere;

[0136] S4. On the undoped GaN layer, at a temperature of 1060 °C and a growth pressure of 200 torr, grow a 3-μm n-GaN layer with a Si doping concentration of 8×10 18 cm -3 , the Ga source required for growth is the TMG source, and the growth atmosphere is H 2 atmosphere;

[0137] S5. On the n-GaN layer, grow an insertion layer unit; including:

[0138] S51. At a temperature of 760 °C and a growth pressure of 250 torr, grow a 20-nm pre-GaN insertion layer. The Ga source required for growth is the TMG source, and the growth atmosphere is H 2 atmosphere;

[0139] S52. At a temperature of 620 °C and a growth pressure of 250 torr, switch to an oxygen-containing TMG source and grow a Ga 2 O 3 insertion layer. Turn off the oxygen-containing TMG source and heat up the temperature to 720 °C for annealing to obtain a Ga 2 O 3 insertion layer with a thickness of 1 nm. The growth atmosphere is N 2 atmosphere;

[0140] S53. Grow a 100 - nm post - GaN insertion layer at a temperature of 760 °C and a growth pressure of 250 torr. The Ga source required for growth is TMG source, and the growth atmosphere is H 2 atmosphere;

[0141] S6. On the post - GaN insertion layer, grow an InGaN / GaN multi - quantum well light - emitting layer at a temperature of 750 °C and a growth pressure of 250 torr. It is a periodic repetition of alternating growth of InGaN quantum well layers and GaN quantum barrier layers. The repetition period of the InGaN / GaN multi - quantum well light - emitting layer is 9. The growth temperature of the InGaN quantum well layer is 750 °C, and the thickness is 3 nm. The growth temperature of the GaN quantum barrier layer is 850 °C, and the thickness is 12 nm;

[0142] S7. On the InGaN / GaN multi - quantum well light - emitting layer, grow a first pGaN layer with a thickness of 40 nm at a temperature of 770 °C and a growth pressure of 200 torr. The Mg doping concentration is 5×10 19 cm -3 , the Ga source required for growth is TMG source, and the Mg source is Cp 2 Mg, and the growth atmosphere is H 2 atmosphere;

[0143] S8. On the first pGaN layer, grow a pAlGaN layer with a thickness of 25 nm at a temperature of 950 °C and a growth pressure of 100 torr. The Mg doping concentration is 5×10 19 cm -3 , the Ga source required for growth is TMG source, and the Mg source is Cp 2 Mg, and the growth atmosphere is H 2 atmosphere;

[0144] S8. On the pAlGaN layer, grow a second pGaN layer with a thickness of 150 nm at a temperature of 930 °C and a growth pressure of 200 torr. The Mg doping concentration is 5×10 19 cm -3 , the Ga source required for growth is TMG source, and the Mg source is Cp 2 Mg, and the growth atmosphere is switched to H 2 atmosphere.

[0145] That is, in the preparation method of the existing LED epitaxial wafer in Comparative Example 2, add the insertion layer unit in Example 1.

[0146] After testing, the PL test brightness (unitless) of the LED epitaxial wafers obtained in Example 1, Example 2, Example 3 and Comparative Example 1 were 125, 138, 132 and 119 respectively. Compared with Comparative Example 1, the brightness of the epitaxial wafers obtained by the preparation method of the present invention was significantly improved, which could be increased by 5% to 15%. At the same time, it shows that Ga 2 O 3 The thickness of the insertion layer is not the lower the better, nor the higher the better.

[0147] For the same chip preparation process, a chip area of 1mm 2 Under the test condition of 1000 mA current:

[0148] The droop ratio (test value at 1000 mA: IQE peak value) of Example 1, Example 2, Example 3 and Comparative Example 1 were 42.2%, 38.8%, 35.4% and 46.5% respectively. Compared with Comparative Example 1, the droop effect of the epitaxial wafers of the present invention was improved. At the same time, it shows that Ga 2 O 3 The higher the thickness of the Ga 2 O 3 insertion layer, the more obvious the improvement of the droop effect, but the brightness decreases. Preferably, the optimal thickness of the Ga

[0149] O insertion layer is 5 nm - 10 nm. While ensuring better brightness, the droop effect can also be significantly reduced. 2 O 3 It should be noted that when the thickness of the Ga

[0150] insertion layer of the present invention is too large, the brightness of the corresponding epitaxial wafer decreases, but the droop ratio is significantly improved. Therefore, the specific thickness should be adjusted according to the actual process and specific application performance requirements.

[0151] By adjusting the growth temperature of the pre - GaN insertion layer in Example 4, compared with Example 1, the chip voltage decreased by 0.02 V, but the brightness of the epitaxial wafer decreased.

[0152] By comparing Example 1, Comparative Example 2 and Comparative Example 3, Comparative Example 2 had the lowest brightness and the largest droop. The droop of Comparative Example 3 was basically equivalent to that of Example 1, but the brightness was low and the voltage increased. Therefore, there is no need to grow a traditional pAlGaN layer in the present invention.

[0153] The above embodiments are only preferred embodiments cited to fully illustrate the present invention, and the protection scope of the present invention is not limited thereto. Equivalent substitutions or transformations made by those skilled in the art in the technical field on the basis of the present invention are all within the protection scope of the present invention. The protection scope of the present invention shall be subject to the claims.

Claims

1. Method for preparing LED epitaxial wafer, Characterized in that, Comprising the following steps: S1. Provide a substrate; S2. Grow a nitride buffer layer on the substrate; S3. Grow an undoped nitride layer on the nitride buffer layer; S4. Grow an n-type nitride layer on the undoped nitride layer; S5. Grow an insertion layer unit on the n-type nitride layer. The insertion layer unit includes a pre-nitride insertion layer, an oxide insertion layer, and a post-nitride insertion layer grown in sequence. Among them, the oxide insertion layer is Ga 2 O 3 , and the thickness of the oxide insertion layer is 1 to 10 nm; S6. Grow a quantum well light-emitting layer on the insertion layer unit; S7. Grow a p-type layer on the quantum well light-emitting layer.

2. The method for preparing an LED epitaxial wafer according to claim 1, Characterized in that, In step S5, the oxide insertion layer is grown by the following method: On the pre-nitride insertion layer, use an oxygen-containing MO source to grow an oxide insertion layer; then turn off the oxygen-containing MO source, raise the temperature and anneal to obtain the oxide insertion layer.

3. The method for preparing an LED epitaxial wafer according to claim 2, Characterized in that, The oxygen-containing MO source is one or two of oxygen-containing trimethylgallium and oxygen-containing triethylgallium.

4. The method for preparing an LED epitaxial wafer according to claim 1, Characterized in that, The thickness of the post-nitride insertion layer is greater than that of the pre-nitride insertion layer.

5. The method for preparing an LED epitaxial wafer according to claim 1, Characterized in that, The pre-nitride insertion layer is GaN, AlGaN or InGaN.

6. The method for preparing an LED epitaxial wafer according to claim 1, Characterized in that, The post-nitride insertion layer is GaN, AlGaN or InGaN.

7. LED epitaxial wafer, Characterized in that, Prepared by using the method for preparing an LED epitaxial wafer according to any one of claims 1-6.

8. Semiconductor device, Characterized in that: Comprises the LED epitaxial wafer according to claim 7.

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