CN117766652A - Light-emitting diode epitaxial wafer, preparation method thereof and light-emitting diode - Google Patents

Abstract

The invention discloses a light-emitting diode epitaxial wafer, a preparation method thereof and a light-emitting diode, and relates to the field of semiconductor photoelectric devices. The epitaxial wafer sequentially comprises a substrate, a buffer layer, an undoped GaN layer, an N-type GaN layer, a multiple quantum well layer, an electron blocking layer, a P-type GaN layer and a P-type contact layer; the multi-quantum well layer is of a periodic structure, and each period also comprises a quantum well layer, an insertion layer, a carrier regulating layer and a quantum barrier layer which are sequentially laminated; the quantum well layer is an InGaN layer, the insertion layer is a GaSe layer, the thickness of the insertion layer is less than or equal to 1.5nm, the carrier regulating layer is a P-type AlGaN layer, and the quantum barrier layer is a GaN layer. By implementing the invention, the luminous efficiency of the light-emitting diode can be improved.

Description

Light-emitting diode epitaxial wafer, preparation method thereof and light-emitting diode

Technical Field

The invention relates to the field of semiconductor photoelectric devices, in particular to a light-emitting diode epitaxial wafer, a preparation method thereof and a light-emitting diode.

Background

The multi-quantum well layer in the GaN-based LED epitaxial structure obtained by the MOCVD method at present is usually composed of InGaN/GaN, the InGaN is used as a well layer, the GaN is used as a barrier layer, a larger polarized electric field exists between the InGaN and the GaN due to lattice mismatch, so that the energy band between the well barriers is inclined, and the overlapping rate of electron hole wave functions in the quantum well is not high; because electrons are light in weight and high in migration rate, the GaN barrier layer is difficult to limit electrons in the quantum well, and electrons in the quantum well easily overflow the barrier layer to the p-type layer; however, an electron blocking layer EBL is usually disposed between the quantum wells and the p-type layer to block electrons from overflowing to the p-type layer, and due to the mismatch of electron and hole migration rates, the electron holes undergoing radiative recombination are mainly concentrated in a few quantum wells close to the p-type layer, while the quantum wells close to the n-type layer contribute little or hardly participate in luminescence, resulting in poor luminescence uniformity of the multiple quantum wells, and thus the final internal quantum efficiency is reduced; in addition, the In component In the quantum well is very sensitive to temperature, when the low-temperature InGaN quantum well is grown, and then the high-temperature GaN barrier layer is grown, the In component In the quantum well is separated out, so that the internal quantum efficiency is reduced, and the phenomenon is more serious for a green LED with high In component.

Disclosure of Invention

The invention aims to solve the technical problem of providing a light-emitting diode epitaxial wafer and a preparation method thereof, which can improve the luminous efficiency of a light-emitting diode.

In order to solve the problems, the invention discloses a light-emitting diode epitaxial wafer, which comprises a substrate, a buffer layer, an undoped GaN layer, an N-type GaN layer, a multiple quantum well layer, an electron blocking layer, a P-type GaN layer and a P-type contact layer which are sequentially laminated on the substrate; the multi-quantum well structure is characterized in that the multi-quantum well layer is of a periodic structure, and each period also comprises a quantum well layer, an insertion layer, a carrier regulating layer and a quantum barrier layer which are sequentially stacked;

the quantum well layer is an InGaN layer, the insertion layer is a GaSe layer, the thickness of the insertion layer is less than or equal to 1.5nm, the carrier regulating layer is a P-type AlGaN layer, and the quantum barrier layer is a GaN layer.

As an improvement of the technical scheme, the thickness of the InGaN layer is 2 nm-4 nm, and the in component accounts for 0.15-0.45;

the thickness of the GaSe layer is 0.7 nm-1.4 nm;

the thickness of the P-type AlGaN layer is 0.5 nm-3 nm, the Al component ratio is 0-1, and the doping concentration is 1 multiplied by 10 ¹⁶ cm ^-3 ～1×10 ¹⁸ cm ^-3 ；

The thickness of the GaN layer is 8 nm-15 nm.

As an improvement of the technical scheme, the Al composition of the P-type AlGaN layer in the multiple quantum well layers of different periods is changed in a decreasing manner along the growth direction of the light-emitting diode epitaxial wafer.

As an improvement of the technical scheme, the In component In the InGaN layer accounts for 0.25-0.45;

the thickness of the GaSe layer is 1 nm-1.4 nm.

As an improvement of the technical scheme, the Al composition of the P-type AlGaN layer in each multiple quantum well layer is changed in a decreasing manner along the growth direction of the LED epitaxial wafer.

As an improvement of the technical scheme, in the multiple quantum well layers of two adjacent periods, the maximum value of the Al component in the P-type AlGaN layer in the n-th multiple quantum well layer is larger than the maximum value of the Al component in the P-type AlGaN layer in the n+1-th multiple quantum well layer,

the minimum value of the Al composition in the P-type AlGaN layer in the n-th multiple quantum well layer is larger than the minimum value of the Al composition in the P-type AlGaN layer in the n+1-th multiple quantum well layer.

As an improvement of the technical scheme, the maximum value of the Al component of the P-type AlGaN layer in the first multiple quantum well layer is 0.8-1, and the minimum value is 0.2-0.4; the maximum value of the Al component in the last multi-quantum well layer is 0.3-0.5, and the minimum value is 0-0.1.

Correspondingly, the invention also discloses a preparation method of the light-emitting diode epitaxial wafer, which is used for preparing the light-emitting diode epitaxial wafer and comprises the following steps:

providing a substrate, and sequentially growing a buffer layer, an undoped GaN layer, an N-type GaN layer, a multiple quantum well layer, an electron blocking layer, a P-type GaN layer and a P-type contact layer on the substrate; the multi-quantum well layer is of a periodic structure, and each period also comprises a quantum well layer, an insertion layer, a carrier regulating layer and a quantum barrier layer which are sequentially laminated;

the quantum well layer is an InGaN layer, the insertion layer is a GaSe layer, the thickness of the insertion layer is less than or equal to 1.5nm, the carrier regulating layer is a P-type AlGaN layer, and the quantum barrier layer is a GaN layer.

As improvement of the technical scheme, the growth temperature of the InGaN layer is 720-820 ℃ and the growth pressure is 100-200 torr;

the growth temperature of the GaSe layer is 620-720 ℃, and the growth pressure is 1-5 torr;

the growth temperature of the P-type AlGaN layer is 850-950 ℃ and the growth pressure is 50-100 torr;

the growth temperature of the GaN layer is 850-950 ℃, and the growth pressure is 100-300 torr.

Correspondingly, the invention also discloses a light-emitting diode, which comprises the light-emitting diode epitaxial wafer.

The implementation of the invention has the following beneficial effects:

1. in the LED epitaxial wafer, the multi-quantum well layer in each period comprises the InGaN layer, the GaSe layer, the P-type AlGaN layer and the GaN layer, wherein the GaSe layer is made of a two-dimensional layered material, and the P-type AlGaN layer and the GaN layer grown on the GaSe layer are mainly subjected to the van der Waals force effect, so that the polarized electric field generated by lattice mismatch between well barriers can be greatly reduced, the wave function overlapping rate of electron holes in the quantum well can be improved, and the internal quantum efficiency of the LED can be improved. The P-type AlGaN layer not only can provide a certain amount of holes, but also can effectively limit the current of electrons in the multiple quantum well layers, so that the electrons are prevented from overflowing to the P-type GaN layer, the distribution of the electrons and the holes in the multiple quantum well layers is more uniform, and the luminous efficiency is improved.

2. The GaSe layer grows between the P-type AlGaN layer and the InGaN layer, and the precipitation of In components In the quantum well layer (InGaN layer) is reduced due to low growth temperature, so that the In components are distributed more uniformly. The method is more suitable for the growth of the high In component type LED, and In addition, the GaSe layer can also effectively prevent the doped element Mg In the P-type AlGaN layer from entering the quantum well layer, so that the crystal quality of the quantum well layer is reduced.

3. In the multiple quantum well layers with different periods, the maximum value of the Al component in the P-type AlGaN layer in the n-th multiple quantum well layer is controlled to be larger than the maximum value of the Al component in the P-type AlGaN layer in the n+1th multiple quantum well layer, and the minimum value of the Al component in the P-type AlGaN layer in the n-th multiple quantum well layer is controlled to be larger than the minimum value of the Al component in the P-type AlGaN layer in the n+1th multiple quantum well layer. Based on the control, the polarization field between the high In component quantum well layer and the quantum barrier layer can be further weakened, and the energy band inclination is reduced; meanwhile, a step blocking effect can be formed on electrons, so that the distribution uniformity of electrons in the whole multi-quantum well layer area is further optimized, and the luminous efficiency is further effectively improved.

Drawings

Fig. 1 is a schematic structural diagram of an led epitaxial wafer according to an embodiment of the present invention;

FIG. 2 is a schematic diagram of a multi-quantum well layer according to an embodiment of the present invention;

fig. 3 is a flowchart of a method for manufacturing an led epitaxial wafer according to an embodiment of the present invention.

Detailed Description

The present invention will be described in further detail below in order to make the objects, technical solutions and advantages of the present invention more apparent.

Referring to fig. 1 and 2, the present invention discloses a light emitting diode epitaxial wafer, which includes a substrate 100, a buffer layer 200, an undoped GaN layer 300, an N-type GaN layer 400, a multiple quantum well layer 500, an electron blocking layer 600, a P-type GaN layer 700, and a P-type contact layer 800, which are sequentially stacked on the substrate 100. Wherein the multiple quantum well layer is of a periodic structure, and the period number of the multiple quantum well layer is 3-15. The multiple quantum well layer 500 of each period includes a quantum well layer 510, an insertion layer 520, a carrier regulating layer 530, and a quantum barrier layer 540, which are sequentially stacked. The quantum well layer 510 is an InGaN layer, and the insertion layer 520 is a GaSe layer with a thickness less than or equal to 1.5nm, so that the layers are stacked in layers to form a two-dimensional stacked structure. The carrier regulating layer 530 is a P-type AlGaN layer, and the quantum barrier layer 540 is a GaN layer. Based on the structure, one can weaken the polarization field caused by the lattice mismatch of the well barrier; holes can be introduced into the quantum well layer 500, so that electron and hole distribution in the quantum well layer is optimized; the three can form effective blocking to electrons, and further optimize the electron and hole distribution in the multi-quantum well layer 500, thereby effectively improving the luminous efficiency of the light emitting diode based on the invention.

Specifically, the thickness of the InGaN layer is 2nm to 5nm, preferably 2nm to 4nm. The InGaN layer has an In component ratio (i.e. the ratio of the molar content of In to the sum of the molar contents of In and Ga) of 0.15-0.5, and the multi-quantum well layer can be applied to blue light, yellow light and green light type light emitting diode epitaxial wafers. Preferably, the In composition of the InGaN layer is 0.15 to 0.45.

Specifically, the thickness of the GaSe layer is 0.7 nm-1.5 nm, and when the thickness is less than 0.7nm, a continuous film structure is difficult to form, mg cannot be blocked, and stress is buffered. When the thickness is more than 1.5nm, the band gap is narrow (about 2.02 eV), and the effect on the carrier confinement is poor, so that the carrier distribution is uneven. Preferably, the thickness of the GaSe layer is 0.7nm to 1.4nm.

Specifically, the thickness of the P-type AlGaN layer is 0.5nm to 3.5nm, preferably 0.5nm to 3nm. The ratio of the Al component in the P-type AlGaN layer is 0to 1, preferably 0.05 to 0.95. The doping element in the P-type AlGaN layer is Mg, and the doping concentration is 1 multiplied by 10 ¹⁶ cm ^-3 ～1×10 ¹⁸ cm ^-3 . Preferably 5X 10 ¹⁶ cm ^-3 ～5×10 ¹⁷ cm ^-3 Lower doping concentrations may enhance the crystalline quality of the layer.

Specifically, the GaN layer has a thickness of 8nm to 15nm, preferably 10nm to 15nm.

Preferably, in one embodiment of the present invention, the Al composition of the P-type AlGaN layer in the multiple quantum well layers of different periods is changed in a decreasing manner along the growth direction of the light emitting diode epitaxial wafer. Specifically, the decreasing change may be a continuous decreasing change or a discontinuous decreasing change, but is not limited thereto. Based on this arrangement, blocking of electrons can be gradually reduced, so that electrons are distributed more uniformly in the multiple quantum well layer 500, thereby improving luminous efficiency.

Preferably, in one embodiment of the present invention, when the quantum well layer 510 uses InGaN with a high In composition, i.e. the In composition ratio In the InGaN layer is 0.25-0.45, the thickness of the GaSe layer is controlled to be 1 nm-1.4 nm, so as to further weaken the polarization field caused by the mismatch of the well barriers, improve the uniformity of the distribution of the In composition, and further improve the light emitting efficiency. The InGaN well layer with high In composition has a large lattice mismatch with the GaN barrier layer, resulting In a stronger polarization electric field and reduced light emission efficiency. In addition, inN has poor miscibility with GaN, resulting In easy precipitation of In components In InGaN of high In components and non-uniformity of In. By thickening the thickness of the GaSe layer, not only the polarization field can be weakened, but also the distribution uniformity of the In component can be improved.

Further, when the quantum well layer 510 with high In composition is used, the Al composition In each P-type AlGaN layer is controlled to change gradually along the growth direction of the epitaxial wafer. Based on the change trend, partial tensile stress can be introduced, so that compressive stress generated by mismatch of the well barriers is effectively buffered, a polarization field is weakened, and luminous efficiency is improved.

Further, when the quantum well layer 510 of high In composition is employed, in the multiple quantum well layers 500 of adjacent two periods are controlled, the maximum value of Al composition In the P-type AlGaN layer In the n-th multiple quantum well layer 500 is greater than the maximum value of Al composition In the P-type AlGaN layer In the n+1th multiple quantum well layer 500, and the minimum value of Al composition In the P-type AlGaN layer In the n-th multiple quantum well layer 500 is greater than the minimum value of Al composition In the P-type AlGaN layer In the n+1th multiple quantum well layer 500. But the minimum value of the Al composition in the P-type AlGaN layer in the nth multiple quantum well layer 500 is smaller than the maximum value of the Al composition in the P-type AlGaN layer in the n+1th multiple quantum well layer 500. Based on the control, the polarization field can be further weakened, the distribution uniformity of electrons is improved, and the luminous efficiency is improved.

Specifically, in one embodiment, the maximum value of the Al composition of the P-type AlGaN layer in the first multiple quantum well layer 500 is controlled to be 0.8 to 1, and the minimum value is controlled to be 0.2 to 0.4; the maximum value of the Al component in the last multi-quantum well layer 500 is 0.3-0.5, and the minimum value is 0-0.1.

Among them, the substrate 100 is a sapphire substrate, a silicon substrate, or a carbonized substrate, but is not limited thereto.

The buffer layer 200 is an AlN layer or an AlGaN layer, but is not limited thereto. An AlN layer is preferred. The thickness of the buffer layer 200 is 15nm to 50nm.

Wherein the thickness of the undoped GaN layer 300 is 1 μm to 3 μm. The thickness of the N-type GaN layer 400 is 1 μm to 3 μm, and the Si doping concentration thereof is 5×10 ¹⁸ cm ^-3 ～1×10 ²⁰ cm ^-3 。

The electron blocking layer 600 is an AlGaN layer or an AlInGaN layer, but is not limited thereto. Preferably, in one embodiment of the present invention, the electron blocking layer 600 is an AlGaN layer having an Al composition ratio of 0.1 to 0.5 and a thickness of 20nm to 100nm.

Wherein the thickness of the P-type GaN layer 700 is 30 nm-100 nm, and the Mg doping concentration is 1×10 ¹⁹ cm ^-3 ～5×10 ²⁰ cm ^-3 。

The P-type contact layer 800 is a heavily doped Mg-type GaN layer or a P-type InGaN layer, but is not limited thereto. Preferably, in one embodiment of the present invention, the P-type contact layer is a heavily doped Mg-type GaN layer having a Mg doping concentration of 5×10 ¹⁹ cm ^-3 ～1×10 ²¹ cm ^-3 The thickness is 10 nm-50 nm.

Correspondingly, referring to fig. 3, the invention also provides a preparation method of the light-emitting diode epitaxial wafer, which is used for preparing the light-emitting diode epitaxial wafer and specifically comprises the following steps:

s1: providing a substrate;

s2: sequentially growing a buffer layer, an undoped GaN layer, an N-type GaN layer, a multiple quantum well layer, an electron blocking layer, a P-type GaN layer and a P-type contact layer on a substrate;

preferably, in some embodiments of the present invention, step S2 includes:

s21: growing a buffer layer on a substrate;

wherein in one embodiment of the invention, an AlN layer is grown by PVD as a buffer layer; the growth temperature is 400-650 ℃, the growth pressure is 1-10 torr, and the sputtering power is 2000-4000W.

After sputtering, loading the substrate into MOCVD, and carrying out in-situ annealing treatment under hydrogen atmosphere, wherein the annealing temperature is 1000-1200 ℃, the annealing pressure is 150-500 torr, and the annealing time is 5-10 min.

S22: growing an undoped GaN layer on the buffer layer;

wherein in one embodiment of the invention, the undoped GaN layer is grown by MOCVD. The growth temperature is 1050-1200 deg.c and the growth pressure is 100-300 torr.

S23: growing an N-type GaN layer on the undoped GaN layer;

in one embodiment of the invention, the N-type GaN layer is grown by MOCVD at 1100-1200 deg.C under 100-300 torr.

S24: growing a multi-quantum well layer on the N-type GaN layer;

wherein, in one embodiment of the present invention, step S24 includes:

s241: growing a quantum well layer;

in one embodiment of the present invention, the InGaN layer is grown by MOCVD, and the growth temperature is 720 ℃ to 820 ℃ and the growth pressure is 100torr to 200torr as the quantum well layer.

S242: growing an insertion layer on the quantum well layer;

in one embodiment of the invention, the GaSe layer is grown by MOCVD and used as an insertion layer, wherein the growth temperature is 620-720 ℃ and the growth pressure is 1-5 torr.

S243: growing a carrier regulating layer on the insertion layer;

wherein in one embodiment of the present invention, a P-type AlGaN layer is grown by MOCVD as a carrier modulation layer. The growth temperature is 850-950 deg.c and the growth pressure is 50-100 torr.

S244: growing a quantum barrier layer on the carrier regulating layer;

wherein in one embodiment of the invention, the GaN layer is grown by MOCVD as a quantum barrier layer. The growth temperature is 850-950 deg.c and the growth pressure is 100-300 torr.

S245: steps S241 to S244 are periodically repeated until a multi-quantum well layer is obtained.

S25: growing an electron blocking layer on the multiple quantum well layer;

in one embodiment of the invention, the AlGaN layer is grown by MOCVD and used as an electron blocking layer, wherein the growth temperature is 1000-1100 ℃ and the growth pressure is 50-300 torr.

S26: growing a P-type GaN layer on the electron blocking layer;

specifically, in one embodiment of the present invention, the P-type GaN layer is grown by MOCVD at a growth temperature of 950 ℃ to 1050 ℃ and a growth pressure of 100torr to 500torr.

S27: growing a P-type contact layer on the P-type GaN layer;

specifically, in one embodiment of the present invention, a heavily doped Mg-type GaN layer is grown by MOCVD, and the growth temperature is 950 ℃ to 1050 ℃ and the growth pressure is 100torr to 300torr as a P-type contact layer.

The invention is further illustrated by the following examples:

example 1

Referring to fig. 1 and 2, the present embodiment provides a light emitting diode epitaxial wafer, which includes a substrate 100, a buffer layer 200, an undoped GaN layer 300, an N-type GaN layer 400, a multiple quantum well layer 500, an electron blocking layer 600, a P-type GaN layer 700, and a P-type contact layer 800 sequentially stacked on the substrate 100.

The substrate 100 is a sapphire substrate, and the buffer layer 200 is an AlN layer, and has a thickness of 30nm. The thickness of the undoped GaN layer 300 was 2.5 μm. The doping concentration of the N-type GaN layer 400 is 1.5X10 ¹⁹ cm ^-3 The thickness thereof was 2.5. Mu.m.

The multi-quantum well layer 500 has a periodic structure, and the number of periods is 10, and each period includes a quantum well layer 510, an insertion layer 520, a carrier regulating layer 530, and a quantum barrier layer 540, which are sequentially stacked. Wherein the quantum well layer 510 is In _0.3 Ga _0.7 N layer with thickness of 3.4nm. The intercalating layer 520 is a GaSe layer with a thickness of 0.7nm. Carrier regulationLayer 530 is a P-type AlGaN layer having a thickness of 2nm and a Mg doping concentration of 1 x 10 ¹⁸ cm ^-3 The Al composition ratio was 0.3 and was maintained constant in each layer. The quantum barrier layer 540 is a GaN layer with a thickness of 14nm.

Wherein the electron blocking layer 600 is Al _0.4 Ga _0.6 N layer with thickness of 50nm. The thickness of the P-type GaN layer 700 was 80nm, and the Mg doping concentration was 8×10 ¹⁹ cm ^-3 . The P-type contact layer 800 is a heavily doped Mg-type GaN layer with a thickness of 40nm and a Mg doping concentration of 5×10 ²⁰ cm ^-3 。

The preparation method of the light-emitting diode epitaxial wafer in the embodiment comprises the following steps:

(1) A substrate is provided.

(2) Growing a buffer layer on a substrate;

wherein, growing an AlN layer by PVD as a buffer layer; the growth temperature is 500 ℃, the growth pressure is 5torr, and the sputtering power is 2800W.

After sputtering, the substrate was loaded into MOCVD, and in-situ annealing was performed under a hydrogen atmosphere at 1080℃under 300torr for 8 minutes.

(3) Growing an undoped GaN layer on the buffer layer;

wherein the undoped GaN layer is grown by MOCVD. The growth temperature is 1100 ℃ and the growth pressure is 200torr.

(4) Growing an N-type GaN layer on the undoped GaN layer;

wherein, the growth temperature of the N-type GaN layer is 1150 ℃ and the growth pressure is 200torr by MOCVD.

(5) Growing a quantum well layer;

wherein In is grown by MOCVD _0.3 Ga _0.7 And an N layer serving as a quantum well layer. The growth temperature is 750 ℃ and the growth pressure is 150torr;

(6) Growing an insertion layer on the quantum well layer;

wherein, the growth temperature of the GaSe layer is 650 ℃ and the growth pressure is 1torr by MOCVD as the insertion layer.

(7) Growing a carrier regulating layer on the insertion layer;

wherein, the P-type AlGaN layer is grown by MOCVD and is used as a carrier regulating layer. The growth temperature is 900 ℃ and the growth pressure is 80torr.

(8) Growing a quantum barrier layer on the carrier regulating layer;

wherein, the GaN layer is grown by MOCVD as a quantum barrier layer. The growth temperature is 920 ℃, and the growth pressure is 150torr.

(9) And (5) periodically repeating the steps (5) to (8) until a multi-quantum well layer is obtained.

(10) Growing an electron blocking layer on the multiple quantum well layer;

wherein Al is grown by MOCVD _0.4 Ga _0.6 The N layer is used as an electron blocking layer, the growth temperature is 1020 ℃, and the growth pressure is 150torr.

(11) Growing a P-type GaN layer on the electron blocking layer;

specifically, the P-type GaN layer is grown by MOCVD at a growth temperature of 1000 ℃ and a growth pressure of 300torr.

(12) Growing a P-type contact layer on the P-type GaN layer;

wherein, the heavily doped Mg-type GaN layer is grown by MOCVD, and is used as a P-type contact layer, the growth temperature is 1020 ℃, and the growth pressure is 200torr.

Example 2

The present embodiment provides a light emitting diode epitaxial wafer, which is different from embodiment 1 in that:

the thickness of the GaSe layer was 1.4nm.

The remainder was the same as in example 1.

Example 3

The present embodiment provides a light emitting diode epitaxial wafer, which is different from embodiment 2 in that:

along the growth direction of the light emitting diode epitaxial wafer, the Al composition of the P-type AlGaN layer in the multiple quantum well layers 500 in different periods is continuously and progressively changed. I.e., the ratio of the Al composition in the P-type AlGaN layer in the n-th period > the ratio of the Al composition in the P-type AlGaN layer in the n+1th period. The Al composition in the P-type AlGaN layer in the multiple quantum well layer is maintained constant for each period.

In the first period of the multiple quantum well layer 500, the ratio of the Al component in the P-type AlGaN layer is 0.78, and in the last period of the multiple quantum well layer 500, the ratio of the Al component in the P-type AlGaN layer is 0.1.

The remainder was the same as in example 2.

Example 4

The present embodiment provides a light emitting diode epitaxial wafer, which is different from embodiment 2 in that:

in the multiple quantum well layers 500 with different periods, the Al component ratio of the P-type AlGaN layer in the multiple quantum well layers 500 with different periods continuously decreases along the growth direction of the light emitting diode epitaxial wafer, and in the single-layer P-type AlGaN layer, the Al component also continuously decreases along the thickness increasing direction. That is, the minimum value of the ratio of Al composition in the P-type AlGaN layer in the n-th period multiple quantum well layer 500 is the same as the maximum value of the ratio of Al composition in the P-type AlGaN layer in the n+1-th period multiple quantum well layer 500.

In the first period of the multiple quantum well layer 500, the maximum value of the Al composition ratio in the P-type AlGaN layer is 0.78, and in the last period of the multiple quantum well layer 500, the minimum value of the Al composition ratio in the P-type AlGaN layer is 0.1.

The remainder was the same as in example 2.

Example 5

The present embodiment provides a light emitting diode epitaxial wafer, which is different from embodiment 2 in that:

in the multiple quantum well layers 500 of different periods, the Al composition ratio of the P-type AlGaN layer in the multiple quantum well layers 500 of different periods changes gradually but does not change continuously along the growth direction of the light emitting diode epitaxial wafer. In the single-layer P-type AlGaN layer, the Al component also continuously and progressively changes along the thickness increasing direction. That is, the minimum value of the ratio of Al composition in the P-type AlGaN layer in the n-th period multiple quantum well layer 500 is different from the maximum value of the ratio of Al composition in the P-type AlGaN layer in the n+1-th period multiple quantum well layer 500.

In the 1 st to 10 th periods, the maximum values of the Al component proportion of the P-type AlGaN layer are respectively 0.9, 0.83, 0.77, 0.7, 0.64, 0.57, 0.51, 0.45, 0.4 and 0.33; the minimum values are 0.38, 0.34, 0.28, 0.24, 0.2, 0.16, 0.12, 0.08, 0.04 and 0, respectively.

The remainder was the same as in example 2.

Comparative example 1

This comparative example provides a light emitting diode epitaxial wafer, which differs from example 1 in that:

the preparation method does not comprise an inserting layer and a carrier regulating layer, and correspondingly, the preparation method also does not comprise the preparation steps of the two layers.

The remainder was the same as in example 1.

Comparative example 2

This comparative example provides a light emitting diode epitaxial wafer, which differs from example 1 in that:

the preparation method does not comprise a carrier regulating layer and correspondingly does not comprise the preparation step of the layer.

The remainder was the same as in example 1.

Comparative example 3

This comparative example provides a light emitting diode epitaxial wafer, which differs from example 1 in that:

the intervening layer is not included, and accordingly, the preparation process does not include the step of preparing the layer.

The remainder was the same as in example 1.

The light-emitting diode epitaxial wafers obtained in examples 1to 5 and comparative examples 1to 3 were fabricated into 10×25mil LEDs, and the brightness and operating voltage thereof were measured at 120mA current. The specific results are shown in the following table:

	brightness (mW)	Voltage (V)
			Example 1	124.6	2.78
Example 2	124.8	2.76
			Example 3	125.1	2.81
Example 4	125.9	2.82
			Example 5	126.7	2.80
Comparative example 1	120.6	2.82
			Comparative example 2	123.5	2.75
Comparative example 3	124.3	2.81

While the foregoing is directed to the preferred embodiments of the present invention, it will be appreciated by those skilled in the art that changes and modifications may be made without departing from the principles of the invention, such changes and modifications are also intended to be within the scope of the invention.

Claims (10)

1. The light-emitting diode epitaxial wafer is characterized by comprising a substrate, and a buffer layer, an undoped GaN layer, an N-type GaN layer, a multiple quantum well layer, an electron blocking layer, a P-type GaN layer and a P-type contact layer which are sequentially laminated on the substrate; the multi-quantum well structure is characterized in that the multi-quantum well layer is of a periodic structure, and each period also comprises a quantum well layer, an insertion layer, a carrier regulating layer and a quantum barrier layer which are sequentially stacked;

the quantum well layer is an InGaN layer, the insertion layer is a GaSe layer, the thickness of the insertion layer is less than or equal to 1.5nm, the carrier regulating layer is a P-type AlGaN layer, and the quantum barrier layer is a GaN layer.

2. The light-emitting diode epitaxial wafer of claim 1, wherein the InGaN layer has a thickness of 2nm to 4nm and an in composition ratio of 0.15 to 0.45;

the thickness of the GaSe layer is 0.7 nm-1.4 nm;

the thickness of the P-type AlGaN layer is 0.5 nm-3 nm, the Al component ratio is 0-1, and the doping concentration is 1 multiplied by 10 ¹⁶ cm ^-3 ～1×10 ¹⁸ cm ^-3 ；

The thickness of the GaN layer is 8 nm-15 nm.

3. The light-emitting diode epitaxial wafer of claim 1, wherein the Al composition of the P-type AlGaN layer in the multiple quantum well layers of different periods is progressively changed along the growth direction of the light-emitting diode epitaxial wafer.

4. The light-emitting diode epitaxial wafer of claim 1 or 3, wherein the In component In the InGaN layer is 0.25-0.45;

the thickness of the GaSe layer is 1 nm-1.4 nm.

5. The light-emitting diode epitaxial wafer of claim 4, wherein the Al composition of the P-type AlGaN layer in each multiple quantum well layer is progressively changed in the growth direction of the light-emitting diode epitaxial wafer.

6. The light-emitting diode epitaxial wafer of claim 5, wherein the maximum value of the Al composition in the P-type AlGaN layer in the n-th multiple quantum well layer is larger than the maximum value of the Al composition in the P-type AlGaN layer in the n+1-th multiple quantum well layer in the multiple quantum well layers of adjacent two periods,

the minimum value of the Al composition in the P-type AlGaN layer in the n-th multiple quantum well layer is larger than the minimum value of the Al composition in the P-type AlGaN layer in the n+1-th multiple quantum well layer.

7. The led epitaxial wafer of claim 6, wherein the Al composition of the P-type AlGaN layer in the first multiple quantum well layer has a maximum value of 0.8 to 1 and a minimum value of 0.2 to 0.4; the maximum value of the Al component in the last multi-quantum well layer is 0.3-0.5, and the minimum value is 0-0.1.

8. A method for preparing the light-emitting diode epitaxial wafer, which is used for preparing the light-emitting diode epitaxial wafer according to any one of claims 1to 7, and is characterized by comprising the following steps:

providing a substrate, and sequentially growing a buffer layer, an undoped GaN layer, an N-type GaN layer, a multiple quantum well layer, an electron blocking layer, a P-type GaN layer and a P-type contact layer on the substrate; the multi-quantum well layer is of a periodic structure, and each period also comprises a quantum well layer, an insertion layer, a carrier regulating layer and a quantum barrier layer which are sequentially laminated;

the quantum well layer is an InGaN layer, the insertion layer is a GaSe layer, the thickness of the insertion layer is less than or equal to 1.5nm, the carrier regulating layer is a P-type AlGaN layer, and the quantum barrier layer is a GaN layer.

9. The method for preparing a light-emitting diode epitaxial wafer according to claim 8, wherein the growth temperature of the InGaN layer is 720-820 ℃, and the growth pressure is 100-200 torr;

the growth temperature of the GaSe layer is 620-720 ℃, and the growth pressure is 1-5 torr;

the growth temperature of the P-type AlGaN layer is 850-950 ℃ and the growth pressure is 50-100 torr;

the growth temperature of the GaN layer is 850-950 ℃, and the growth pressure is 100-300 torr.

10. A light emitting diode comprising the light emitting diode epitaxial wafer according to any one of claims 1to 7.