CN105914273B - A kind of reddish yellow light-emitting diode epitaxial wafer and preparation method thereof - Google Patents

Abstract

The invention discloses a red-yellow light-emitting diode epitaxial wafer and a preparation method thereof, belonging to the technical field of semiconductors. The epitaxial wafer includes N-type substrate, N-type buffer layer, N-type reflective layer, N-type confinement layer, electron blocking layer, multiple quantum well layer, hole adjustment layer, P-type confinement layer, P-type current spreading layer, P-type Ohmic contact layer, the electron blocking layer includes an AlGaInP layer and an AlInP layer, the hole adjustment layer includes a first sublayer and at least two second sublayers, the first sublayer is an undoped AlInP layer, and the second sublayer includes P Type-doped AlInP layer and non-doped AlInP layer, the doping concentration of the P-type doped AlInP layer is smaller than the doping concentration of the P-type confinement layer. The invention delays electrons from reaching the multi-quantum well layer through the electron blocking layer, and the hole adjustment layer makes the holes evenly distributed in the area adjacent to the multi-quantum well layer, increases the recombination probability of electrons and holes, and improves the luminous efficiency of the light-emitting diode.

Description

A red-yellow light-emitting diode epitaxial wafer and its preparation method

technical field

The invention relates to the technical field of semiconductors, in particular to a red-yellow light-emitting diode epitaxial wafer and a preparation method thereof.

Background technique

Red and yellow high-brightness AlGaInP-based light-emitting diodes (Light Emitting Diode, referred to as LEDs) have the advantages of small size, long life, and low power consumption. Broad application prospects.

AlGaInP LED epitaxial wafer includes N-type substrate, N-type buffer layer, N-type reflective layer, N-type confinement layer, multiple quantum well layer, P-type confinement layer, P-type current spreading layer, P-type ohmic contact layer from bottom to top .

In the process of realizing the present invention, the inventor finds that there are at least the following problems in the prior art:

The volume and mass of electrons are smaller than holes, so the mobility and mobility of electrons are better than holes. Most of the recombination of electrons and holes occurs in the area adjacent to the P-type confinement layer, and the luminous efficiency is low.

Contents of the invention

In order to solve the problem of low luminous efficiency in the prior art, an embodiment of the present invention provides a red-yellow light-emitting diode epitaxial wafer and a preparation method thereof. Described technical scheme is as follows:

In the first aspect, an embodiment of the present invention provides a red-yellow light-emitting diode epitaxial wafer. The red-yellow light-emitting diode epitaxial wafer includes an N-type substrate and an N-type buffer stacked sequentially on the N-type substrate. layer, N-type reflective layer, N-type confinement layer, multi-quantum well layer, P-type confinement layer, P-type current spreading layer, P-type ohmic contact layer, the red and yellow light emitting diode epitaxial wafer also includes layers stacked on the N An electron blocking layer between the multiple quantum well layer and the multiple quantum well layer, and a hole adjustment layer stacked between the multiple quantum well layer and the P type confinement layer, the electron blocking layer includes an AlGaInP layer and AlInP layer, the hole adjustment layer includes a first sublayer and at least two second sublayers, the first sublayer is arranged on the multi-quantum well layer, and the first sublayer is non-doped An AlInP layer, the second sublayer includes a P-type doped AlInP layer and a non-doped AlInP layer, and the doping concentration of the P-type doped AlInP layer is lower than that of the P-type confinement layer.

Optionally, the thickness of the AlGaInP layer is 20-50 nm.

Optionally, the AlInP layer in the electron blocking layer has a thickness of 8-15 nm.

Optionally, the thickness of the first sublayer is 90-220 nm.

Optionally, the number of layers of the second sub-layer is 2-9 layers.

Optionally, the thickness of the P-type doped AlInP layer is the same as that of the non-doped AlInP layer.

Optionally, the thickness of the P-type doped AlInP layer is 10-20 nm.

Optionally, the thickness of the non-doped AlInP layer is 10-20 nm.

Optionally, the doping impurity of the P-type doped AlInP layer is magnesium element, and the doping concentration of the P-type doped AlInP layer is 10 ^-17 ~5*10 ^-17 cm ^-3 .

In the second aspect, the embodiment of the present invention provides a method for preparing the red-yellow light-emitting diode epitaxial wafer as described in the first aspect, the preparation method comprising:

forming an N-type buffer layer on an N-type substrate;

forming an N-type reflective layer on the N-type buffer layer;

forming an N-type confinement layer on the N-type reflection layer;

forming an electron blocking layer on the N-type confinement layer, the electron blocking layer comprising an AlGaInP layer and an AlInP layer;

forming a multiple quantum well layer on the electron blocking layer;

A hole adjustment layer is formed on the multiple quantum well layer, the hole adjustment layer includes a first sublayer and at least two second sublayers, the first sublayer is formed on the multiple quantum well layer, The first sublayer is an undoped AlInP layer, the second sublayer includes a P-type doped AlInP layer and an undoped AlInP layer, and the doping concentration of the P-type doped AlInP layer is less than The doping concentration of the P-type confinement layer;

forming a P-type confinement layer on the hole adjustment layer;

forming a P-type current spreading layer on the P-type confinement layer;

A P-type ohmic contact layer is formed on the P-type current spreading layer.

The beneficial effects brought by the technical solution provided by the embodiments of the present invention are:

By stacking an electron blocking layer between the N-type confinement layer and the multi-quantum well layer, the electrons are delayed from reaching the multi-quantum well layer, and a hole adjustment layer is stacked between the multi-quantum well layer and the P-type confinement layer, so that the holes are evenly distributed in the The region adjacent to the multi-quantum well layer increases the recombination probability of electrons and holes and improves the luminous efficiency of the light-emitting diode. At the same time, the doping concentration of the hole adjustment layer is relatively low, which can effectively prevent doping impurities from diffusing into the multi-quantum well layer and enhance the probability of non-radiative recombination.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings that need to be used in the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For those skilled in the art, other drawings can also be obtained based on these drawings without creative effort.

FIG. 1 is a schematic structural view of a red-yellow light-emitting diode epitaxial wafer provided in Embodiment 1 of the present invention;

Figure 2a is a schematic diagram of the energy bands of the N-type confinement layer, the electron blocking layer, the multiple quantum well layer, and the P-type confinement layer provided by Embodiment 1 of the present invention;

Fig. 2b is a schematic diagram of the doping concentration distribution of the hole adjustment layer and the P-type confinement layer provided by Embodiment 1 of the present invention;

FIG. 3 is a flow chart of a method for preparing a red-yellow light-emitting diode epitaxial wafer provided by Embodiment 2 of the present invention.

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the implementation manner of the present invention will be further described in detail below in conjunction with the accompanying drawings.

Embodiment one

An embodiment of the present invention provides a red-yellow light-emitting diode epitaxial wafer, as shown in FIG. 1 , the red-yellow light-emitting diode epitaxial wafer includes an N-type substrate 1 and an N-type buffer layer sequentially stacked on the N-type substrate 1 2. N-type reflection layer 3, N-type confinement layer 4, electron blocking layer 5, multiple quantum well layer 6, hole adjustment layer 7, P-type confinement layer 8, P-type current spreading layer 9, P-type ohmic contact layer 10 .

In this embodiment, the N-type substrate 1 is a GaAs substrate; the N-type buffer layer 2 is a GaAs layer; the N-type reflective layer 3 includes alternately stacked AlAs layers 31 and AlGaAs layers 32; the N-type confinement layer 4 is an AlInP layer The electron blocking layer 5 includes AlGaInP layers 51 and AlInP layers 52; the multi-quantum well layer 6 includes alternately stacked quantum well layers 61 and quantum barrier layers 62 (the quantum well layers and the quantum barrier layers are respectively AlGaInP layers with different Al compositions) The hole adjustment layer 7 includes a first sublayer 71 and at least two second sublayers 72, the first sublayer 71 is a non-doped AlInP layer, and the second sublayer includes a P-type doped AlInP layer 72a and a non-doped AlInP layer Doped AlInP layer 72b, the doping concentration of the P-type doped AlInP layer 72a is less than the doping concentration of the P-type confinement layer 8; the P-type confinement layer 8 is an AlInP layer; the P-type current spreading layer 9 is a GaP layer; P Type ohmic contact layer 10 is a GaP layer.

FIG. 2 a is a schematic diagram of the energy bands of the N-type confinement layer 4 , the electron blocking layer 5 , the multi-quantum well layer 6 , and the P-type confinement layer 8 . As shown in Figure 2a, the energy band of the material AlInP used in the N-type confinement layer 4, the AlInP layer 52, and the P-type confinement layer 8 is higher than the energy band of the material AlGaInP used in the AlGaInP layer 51 and the multi-quantum well layer 6, so some electrons It can be blocked in the AlGaInP layer 51 by the AlInP layer 52 to delay electrons from reaching the multi-quantum well layer 6 .

FIG. 2 b is a schematic diagram of the doping concentration distribution of the hole adjustment layer 7 and the P-type confinement layer 8 . As shown in Figure 2b, the doping concentration of the undoped AlInP layer, low-doped AlInP layer, and highly doped AlInP layer gradually increases, and the doping concentration of the P-type doped AlInP layer 72a is lower than that of the P-type confinement layer The doping concentration of 8 is conducive to hole injection into the hole adjustment layer 7; at the same time, considering the easy diffusion of Mg, P-type doped AlInP layers 72a and non-doped AlInP layers 72b are alternately stacked, which can make the holes evenly Distributed in the hole adjustment layer 7; in addition, the first layer adjacent to the multi-quantum well layer 6 adopts a non-doped AlInP layer, which can prevent Mg from diffusing into the multi-quantum well layer 6 to cause non-radiative recombination.

Specifically, the N-type substrate 1 may be a 2 or 4-inch 100-plane-offset <111>A+5° GaAs substrate.

Optionally, the thickness of the N-type substrate 1 may be 340-360 μm.

Optionally, the doping impurity of the N-type substrate 1 may be silicon element, and the doping concentration of the N-type substrate 1 may be 10 ^-18 ~ 2*10 ^-18 cm ^-3 .

Optionally, the thickness of the N-type buffer layer 2 may be 150-250 nm. When the thickness of the N-type buffer layer is less than 150 nm, the defects of the N-type substrate 1 cannot be covered; when the thickness of the N-type buffer layer is greater than 250 nm, it will cause waste.

Optionally, the doping impurity of the N-type buffer layer 2 may be silicon element, and the doping concentration of the N-type buffer layer 2 may be 10 ^-18 ~ 2*10 ^-18 cm ^-3 .

Preferably, the doping concentration of the N-type buffer layer 2 may be 10 ⁻¹⁸ cm ⁻³ .

Optionally, the doping impurity of the N-type reflective layer 3 may be silicon element, and the doping concentration of the N-type reflective layer 3 may be 2*10 ^-18 ~8*10 ^-18 cm ^-3 . When the doping concentration of the N-type reflective layer 3 is less than 2*10 ^-18 cm ^-3 , the forward voltage is higher; when the doping concentration of the N-type reflective layer 3 is greater than 8*10 ^-18 cm ^-3 , too much Impurities in the quantum well cause photons to scatter, which affects the brightness of the chip.

In practical applications, the AlAs layer 31 and the AlGaAs layer 32 are implanted with the same amount of dopants but with different doping concentrations, and the doping concentration of the AlAs layer 31 is lower than that of the AlGaAs layer 32 . Specifically, the doping concentration of the AlAs layer 31 is 2*10 ^-18 ~ 4.5*10 ^-18 cm ^-3 , and the doping concentration of the AlGaAs layer 32 is 4.5*10 ^-18 ~ 8*10 ^-18 cm ^-3 .

Optionally, the sum of the numbers of the AlAs layer 31 and the AlGaAs layer 32 may be 30-60.

It can be understood that the sum of the numbers of the AlAs layer 31 and the AlGaAs layer 32 mainly affects the brightness of the chip. When the number of layers of the AlAs layer 31 and the AlGaAs layer 32 reaches 60, the reflectivity of the outgoing light is basically 100%, and increasing the sum of the layers of the AlAs layer 31 and the AlGaAs layer 32 has little effect, and it will also affect the chip voltage . In practical applications, the sum of the layers of the AlAs layer 31 and the AlGaAs layer 32 can be determined according to product requirements.

Optionally, the thickness of the AlAs layer 31 may be 42-55 nm.

Optionally, the thickness of the AlGaAs layer 32 may be 40-50 nm.

It should be noted that the thickness ranges of the AlAs layer 31 and the AlGaAs layer 32 are determined according to the reflection spectrum, and the reflection effect cannot be obtained beyond the above range. In practical applications, the specific thickness can be determined according to the wavelength of the product produced, and different wavelengths require different thicknesses.

Optionally, the doping impurity of the N-type confinement layer 4 may be silicon element, and the doping concentration of the N-type confinement layer 4 may be 7*10 ^-17 to 2*10 ^-18 cm ^-3 .

Optionally, the thickness of the N-type confinement layer 4 may be 200-500 nm.

Optionally, the thickness of the AlGaInP layer 51 may be 20-50 nm. When the thickness of the AlGaInP layer is less than 20nm, it cannot effectively accommodate enough electrons; when the thickness of the AlGaInP layer is greater than 50nm, there are fewer electrons that cause recombination and light emission.

Preferably, the thickness of the AlGaInP layer 51 may be 35 nm.

Optionally, the thickness of the AlInP layer 52 may be 8-15 nm. When the thickness of the AlInP layer is less than 8nm, it cannot effectively prevent electrons from being injected into the MQW layer; when the thickness of the AlInP layer is greater than 15nm, there are fewer electrons tunneling, resulting in fewer electrons recombined to emit light.

Preferably, the thickness of the AlInP layer 52 may be 12 nm.

Optionally, the thickness of the quantum well layer 61 may be 3-5 nm.

Optionally, the thickness of the quantum barrier layer 62 may be 5-7 nm.

Optionally, the thickness of the first sub-layer 71 may be 90-220 nm. When the thickness of the first sublayer is less than 90nm, doping impurities may diffuse into the multiple quantum wells, causing non-radiative recombination and affecting hole injection; when the thickness of the first sublayer is greater than 220nm, the holes injected into the multiple quantum well layer There are fewer holes.

Preferably, the thickness of the first sub-layer 71 may be 140 nm.

In practical applications, the thickness of the first sublayer can be determined according to the number of layers and the doping concentration of the second sublayer 72 .

Optionally, the number of layers of the second sub-layer 72 may be 2-9 layers. When the number of layers of the second sublayer 72 is less than 2 layers, the distribution of holes cannot be effectively adjusted; when the number of layers of the second sublayer 72 is greater than 9 layers, the number of holes injected into the MQW layer by the P-type confinement layer is less.

Preferably, the number of layers of the second sub-layer 72 may be 5-6 layers.

Optionally, the thickness of the P-type doped AlInP layer 72a and the thickness of the non-doped AlInP layer 72b may be the same, which is beneficial to the uniform distribution of holes.

Optionally, the thickness of the P-type doped AlInP layer 72a may be 10-20 nm. When the thickness of the P-type doped AlInP layer is less than 10 nm, the distribution of holes cannot be effectively adjusted; when the thickness of the hole adjustment layer is greater than 20 nm, the injection of holes is affected.

Preferably, the thickness of the P-type doped AlInP layer 72a may be 14nm.

Optionally, the thickness of the non-doped AlInP layer 72b may be 10-20 nm. When the thickness of the non-doped AlInP layer is less than 10 nm, the distribution of holes cannot be effectively adjusted; when the thickness of the non-doped AlInP layer is greater than 20 nm, the injection of holes is affected.

Preferably, the thickness of the non-doped AlInP layer 72b may be 14nm.

Optionally, the doping impurity of the P-type doped AlInP layer 72a may be magnesium element, and the doping concentration of the P-type doped AlInP layer 72a may be 10 ⁻¹⁷ ~5*10 ⁻¹⁷ cm ⁻³ . When the doping concentration of the P-type doped AlInP layer is less than 10 ^-17 cm ^-3 , the distribution of holes cannot be effectively adjusted; when the doping concentration of the P-type doped AlInP layer is greater than 5*10 ^-17 cm ^-3 When , it causes doping impurities to diffuse into the multi-quantum well layer and enhance the probability of non-radiative recombination.

Preferably, the doping concentration of the P-type doped AlInP layer may be 3*10 ⁻¹⁷ cm ⁻³ .

Optionally, the doping impurity of the P-type confinement layer 8 may be magnesium element, and the doping concentration of the P-type confinement layer 8 may be 7*10 ^-17 ~10 ^-18 cm ^-3 .

Optionally, the thickness of the P-type confinement layer 8 may be 400-600 nm.

Optionally, the doping impurity of the P-type current spreading layer 9 may be magnesium element, and the doping concentration of the P-type current spreading layer 9 may be 2*10 ^-18 ~8*10 ^-18 cm ^-3 . When the doping concentration of the P-type current spreading layer is less than 2*10 ^-18 , the voltage is affected; when the doping concentration of the P-type current spreading layer is greater than 8*10 ^-18 cm ^-3 , the lattice quality is poor, which affects the luminous brightness .

Optionally, the thickness of the P-type current spreading layer 9 may be 8-10 μm. When the thickness of the P-type current spreading layer is less than 8 μm, the current spread is affected; when the thickness of the P-type current spreading layer is greater than 10 μm, the warpage of the epitaxial wafer will increase, resulting in adverse consequences such as flying pieces.

Optionally, the doping impurity of the P-type ohmic contact layer 10 may be carbon element to achieve a higher doping concentration and adapt to a lower growth temperature, and the doping concentration of the P-type ohmic contact layer 10 may be 3*10 ^-19 ~ 10 ^-20 cm ^-3 . When the doping concentration of the P-type ohmic contact layer is less than 3*10 ^-19 cm ^-3 , poor ohmic contact leads to high voltage; when the doping concentration of the P-type ohmic contact layer is greater than 10 ^-20 cm ^-3 , the lattice The quality deteriorates.

Optionally, the thickness of the P-type ohmic contact layer 10 may be 30-100 nm. When the thickness of the P-type ohmic contact layer is less than 30nm, the voltage is difficult to control; when the thickness of the P-type ohmic contact layer is greater than 100nm, the brightness is affected.

In the embodiment of the present invention, an electron blocking layer is stacked between the N-type confinement layer and the multi-quantum well layer to delay electrons from reaching the multi-quantum well layer, and a hole adjustment layer is stacked between the multi-quantum well layer and the P-type confinement layer, so that the holes The holes are evenly distributed in the area adjacent to the multi-quantum well layer, which increases the recombination probability of electrons and holes and improves the luminous efficiency of the light-emitting diode. At the same time, the doping concentration of the hole adjustment layer is relatively low, which can effectively prevent doping impurities from diffusing into the multi-quantum well layer and enhance the probability of non-radiative recombination.

Embodiment two

An embodiment of the present invention provides a method for preparing a red-yellow light-emitting diode epitaxial wafer, which is suitable for preparing the red-yellow light-emitting diode epitaxial wafer provided in Example 1, see FIG. 3 , the preparation method includes:

Step 201: forming an N-type buffer layer on an N-type substrate.

In this embodiment, the N-type substrate is a GaAs substrate; the N-type buffer layer is a GaAs layer.

Specifically, the N-type substrate can be a 2 or 4-inch 100-plane-offset <111>A+5° GaAs substrate.

Optionally, the thickness of the N-type substrate may be 340-360 μm.

Optionally, the doping impurity of the N-type substrate may be silicon element, and the doping concentration of the N-type substrate 1 may be 10 ^-18 ~ 2*10 ^-18 cm ^-3 .

Specifically, the growth conditions of the N-type buffer layer may be as follows: the growth temperature is 640-660° C., the flow rate of TMGa (trimethylgallium) is 80-100 sccm, the flow rate of AsH ₃ (arsine hydrogen) is 400-450 sccm, and the impurity It is silicon element, the doping concentration is 10 ^-18 ~ 2*10 ^-18 cm ^-3 , and the thickness is 150 ~ 250nm.

Step 202: forming an N-type reflective layer on the N-type buffer layer.

In this embodiment, the N-type reflective layer includes alternately stacked AlAs layers and AlGaAs layers.

Specifically, the growth conditions of the N-type reflective layer may be as follows: the growth temperature is 640-660° C., the flow rate of TMGa is 80-120 sccm, the flow rate of TMAl (trimethylaluminum) is 180-320 sccm, the flow rate of AsH ₃ is 400-500 sccm, AlAs The thickness of the layer is 42-55nm, the thickness of the AlGaAs layer is 40-50nm, the sum of the layers of the AlAs layer and the AlGaAs layer is 30-60, the doping impurity is silicon element, and the doping concentration is 2* ^10-18-8 * ^10-18 cm ^-3 .

Step 203: forming an N-type confinement layer on the N-type reflection layer.

In this embodiment, the N-type confinement layer is an AlInP layer.

Specifically, the growth conditions of the N-type confinement layer may be as follows: the growth temperature is 660-680° C., the flow rate of TMAl is 100-120 sccm, the flow rate of TMIn (trimethyl indium) is 800-850 sccm, the flow rate of PH ₃ is 900-1100 sccm, and the flow rate of doped The impurity is silicon element, the doping concentration is 7*10 ^-17 ~ 2*10 ^-18 cm ^-3 , and the thickness is 200 ~ 500nm.

Step 204: forming an electron blocking layer on the N-type confinement layer.

In this embodiment, the electron blocking layer includes an AlGaInP layer and an AlInP layer.

Specifically, the growth conditions of the electron blocking layer may be as follows: the growth temperature is 660-680° C., the TMIn flow rate is 800-850 sccm, and the pH ₃ flow rate is 900-1100 sccm; the TMAl flow rate of the AlGaInP layer is 6-35 sccm, and the TMGa flow rate is 26-26 sccm. 40 sccm; the TMAl flow rate of the AlInP layer is 100-120 sccm; the thickness of the AlGaInP layer is 20-50 nm, and the thickness of the AlInP layer is 8-15 nm.

Step 205: forming a multi-quantum well layer on the electron blocking layer.

In this embodiment, the multi-quantum well layer includes alternately stacked quantum well layers and quantum barrier layers (the quantum well layers and the quantum barrier layers are respectively AlGaInP layers with different Al compositions).

Specifically, the growth conditions of the quantum well layer may be as follows: the growth temperature is 660-680° C., the flow rate of TMGa is 26-40 sccm, the flow rate of TMAl is 6-35 sccm, the flow rate of TMIn is 800-850 sccm, the flow rate of PH ₃ is 900-1100 sccm, the thickness It is 3~5nm.

The growth conditions of the quantum barrier layer can be as follows: the growth temperature is 660-680 ℃, the flow rate of TMGa is 5-18 sccm, the flow rate of TMAl is 70-100 sccm, the flow rate of TMIn is 800-850 sccm, the flow rate of PH ₃ is 900-1100 sccm, and the thickness is 5-100 sccm. 7nm.

Step 206: forming a hole adjustment layer on the multiple quantum well layer.

In this embodiment, the hole adjustment layer includes a first sublayer and at least two second sublayers, the first sublayer is a non-doped AlInP layer, and the second sublayer includes a P-type doped AlInP layer and a non-doped AlInP layer. For the doped AlInP layer, the doping concentration of the P-type doped AlInP layer is lower than the doping concentration of the P-type confinement layer.

Specifically, the growth conditions of the hole adjustment layer may be as follows: the growth temperature is 660-680° C., the flow rate of TMAl is 100-120 sccm, the flow rate of TMIn is 800-850 sccm, the flow rate of PH ₃ is 900-1100 sccm, and the thickness of the first sublayer is 90-220nm, the number of layers of the second sub-layer is 2-9 layers, the thickness of the P-type doped AlInP layer is 10-20nm, the thickness of the non-doped AlInP layer is 10-20nm, the P-type doped AlInP layer The doping impurity of the layer is magnesium element, and the doping concentration of the P-type doped AlInP layer is 10 ^-17 ~ 5*10 ^-17 cm ^-3 .

Step 207: forming a P-type confinement layer on the hole adjustment layer.

In this embodiment, the P-type confinement layer is an AlInP layer.

Specifically, the growth conditions of the P-type confinement layer may be as follows: the growth temperature is 660-680° C., the flow rate of TMAl is 100-120 sccm, the flow rate of TMIn is 800-850 sccm, the flow rate of PH ₃ is 900-1100 sccm, and the doping impurity is magnesium element. The doping concentration is 7*10 ^-17 to 10 ^-18 cm ^-3 , and the thickness is 400 to 600 nm.

Step 208: forming a P-type current spreading layer on the P-type confinement layer.

In this embodiment, the P-type current spreading layer is a GaP layer.

Specifically, the growth conditions of the P-type current spreading layer may be as follows: the growth temperature is 690-710° C., the flow rate of TMGa is 400-600 sccm, the flow rate of PH ₃ is 200-500 sccm, the doping impurity is magnesium element, and the doping concentration is 2* 10 ^-18 to 8*10 ^{- 18} cm ^-3 , with a thickness of 8 to 10 μm.

Step 209: forming a P-type ohmic contact layer on the P-type current spreading layer.

In this embodiment, the P-type ohmic contact layer is a GaP layer.

Specifically, the growth conditions of the P-type ohmic contact layer can be as follows: the growth temperature is 630-650° C., the flow rate of TMGa is 400-600 sccm, the flow rate of PH ₃ is 200-500 sccm, the doping impurity is carbon element, and the doping concentration is 3* 10 ^-19 to 10 ^-20 cm ^-3 , with a thickness of 30 to 100 nm.

In the embodiment of the present invention, an electron blocking layer is stacked between the N-type confinement layer and the multi-quantum well layer to delay electrons from reaching the multi-quantum well layer, and a hole adjustment layer is stacked between the multi-quantum well layer and the P-type confinement layer, so that the holes The holes are evenly distributed in the area adjacent to the multi-quantum well layer, which increases the recombination probability of electrons and holes and improves the luminous efficiency of the light-emitting diode. At the same time, the doping concentration of the hole adjustment layer is relatively low, which can effectively prevent doping impurities from diffusing into the multi-quantum well layer and enhance the probability of non-radiative recombination.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection of the present invention. within range.

Claims (10)

1. A red-yellow light-emitting diode epitaxial wafer, said red-yellow light-emitting diode epitaxial wafer comprising an N-type substrate, and an N-type buffer layer, an N-type reflection layer, and an N-type layer stacked sequentially on said N-type substrate. Type confinement layer, multi-quantum well layer, P-type confinement layer, P-type current spreading layer, P-type ohmic contact layer, characterized in that, the red and yellow light emitting diode epitaxial wafer also includes layers stacked on the N-type confinement layer and The electron blocking layer between the multiple quantum well layers, and the hole adjustment layer laminated between the multiple quantum well layer and the P-type confinement layer, the electron blocking layer includes an AlGaInP layer and an AlInP layer, so The hole adjustment layer includes a first sublayer and at least two second sublayers, the first sublayer is arranged on the multi-quantum well layer, the first sublayer is an undoped AlInP layer, so The second sublayer includes a P-type doped AlInP layer and a non-doped AlInP layer, and the doping concentration of the P-type doped AlInP layer is smaller than that of the P-type confinement layer. 2 . The red and yellow light emitting diode epitaxial wafer according to claim 1 , wherein the thickness of the AlGaInP layer is 20-50 nm. 3 . The red-yellow light-emitting diode epitaxial wafer according to claim 1 , wherein the thickness of the AlInP layer in the electron blocking layer is 8-15 nm. 4 . 4 . The red and yellow light emitting diode epitaxial wafer according to claim 1 , wherein the thickness of the first sub-layer is 90-220 nm. 5 . The red and yellow light emitting diode epitaxial wafer according to claim 1 , wherein the number of layers of the second sub-layer is 2-9 layers. 6 . The red and yellow light emitting diode epitaxial wafer according to claim 1 , wherein the thickness of the P-type doped AlInP layer is the same as that of the non-doped AlInP layer. 7 . The red and yellow light emitting diode epitaxial wafer according to claim 1 , wherein the thickness of the P-type doped AlInP layer is 10-20 nm. 8 . The red and yellow light emitting diode epitaxial wafer according to claim 1 , wherein the thickness of the non-doped AlInP layer is 10-20 nm. 9. The red-yellow light-emitting diode epitaxial wafer according to claim 1, wherein the doping impurity of the P-type doped AlInP layer is magnesium element, and the doping of the P-type doped AlInP layer The concentration is 10 ^-17 ~5*10 ^-17 cm ^-3 . 10. A preparation method of the red-yellow light-emitting diode epitaxial wafer according to any one of claims 1-9, wherein the preparation method comprises: forming an N-type buffer layer on an N-type substrate; forming an N-type reflective layer on the N-type buffer layer; forming an N-type confinement layer on the N-type reflection layer; forming an electron blocking layer on the N-type confinement layer, the electron blocking layer comprising an AlGaInP layer and an AlInP layer; forming a multiple quantum well layer on the electron blocking layer; A hole adjustment layer is formed on the multiple quantum well layer, the hole adjustment layer includes a first sublayer and at least two second sublayers, the first sublayer is formed on the multiple quantum well layer, The first sublayer is an undoped AlInP layer, the second sublayer includes a P-type doped AlInP layer and an undoped AlInP layer, and the doping concentration of the P-type doped AlInP layer is less than The doping concentration of the P-type confinement layer; forming a P-type confinement layer on the hole adjustment layer; forming a P-type current spreading layer on the P-type confinement layer; A P-type ohmic contact layer is formed on the P-type current spreading layer.