Preparation method of GaN-based light-emitting diode epitaxial wafer and epitaxial wafer

Abstract

The present disclosure provides a method for preparing a GaN-based light-emitting diode epitaxial wafer and an epitaxial wafer, belonging to the field of optoelectronic manufacturing technology. The method for preparing the GaN-based light-emitting diode epitaxial wafer includes: providing a substrate; epitaxially growing an n-type GaN layer on the substrate; epitaxially growing a multi-quantum well layer on the n-type GaN layer; intermittently introducing a Mg source into the reaction chamber in a pulsed manner to form a pretreatment layer on the multi-quantum well layer, wherein the pretreatment layer is a Mg metal layer; and epitaxially growing a p-type GaN layer on the pretreatment layer. The embodiments of the present disclosure can improve the problem of low doping concentration due to the memory effect of Mg when doping Mg in the p-type GaN layer, thereby improving the luminous efficiency of the light-emitting diode chip.

Description

Technical Field

[0001] The present invention relates to the field of optoelectronic manufacturing technology, and in particular to a preparation method of a GaN-based light-emitting diode epitaxial wafer and the epitaxial wafer. Background Art

[0002] Light Emitting Diode (Micro LED) is a semiconductor diode that can convert electrical energy into light energy. It has the advantages of small size, long life, and low power consumption. It is currently widely used in car signal lights, traffic lights, display screens, and lighting equipment. Epitaxial wafers are the basic structure for making light-emitting diodes. The structure of epitaxial wafers includes a substrate and an epitaxial layer grown on the substrate.

[0003] In the related art, GaN-based light-emitting diode epitaxial wafers include: substrate, AlN buffer layer, n-type GaN layer, multi-quantum well layer, p-type GaN layer, electron blocking layer and p-type contact layer. Among them, the p-type GaN layer is usually heavily doped with Mg to increase the hole concentration of the p-type GaN layer and improve the luminous efficiency.

[0004] However, in the process of introducing Mg source into the reaction chamber to dope the p-type GaN layer, especially in the GaN material system, Mg is easily attached to the cavity wall of the reaction chamber due to the memory effect of Mg, which in turn affects the actual doping concentration of Mg in the p-type GaN layer, reduces the hole concentration of the p-type GaN layer, and thus affects the luminous efficiency of the light-emitting diode chip. Summary of the invention

[0005] The disclosed embodiment provides a method for preparing a GaN-based light-emitting diode epitaxial wafer and an epitaxial wafer, which can improve the problem of low doping concentration due to the memory effect of Mg when doping Mg in a p-type GaN layer, and improve the luminous efficiency of the light-emitting diode chip. The technical solution is as follows:

[0006] On the one hand, an embodiment of the present disclosure provides a method for preparing a GaN-based light-emitting diode epitaxial wafer, the preparation method comprising: providing a substrate; epitaxially growing an n-type GaN layer on the substrate; epitaxially growing a multi-quantum well layer on the n-type GaN layer; intermittently introducing a Mg source into a reaction chamber in a pulsed manner to form a pretreatment layer on the multi-quantum well layer, wherein the pretreatment layer is a Mg metal layer; and epitaxially growing a p-type GaN layer on the pretreatment layer.

[0007] Optionally, when the Mg source is introduced in a pulsed manner, the ratio of the time for introducing the Mg source to the time for stopping the introduction of the Mg source is controlled to be 3:1 to 10:1.

[0008] Optionally, the total time for introducing the Mg source is 60 s to 1000 s.

[0009] Optionally, when the Mg source is introduced, the temperature in the reaction chamber is controlled to be 700° C. to 800° C.

[0010] Optionally, when the Mg source is introduced, the pressure in the reaction chamber is controlled to be 200 Torr to 600 Torr.

[0011] Optionally, the Mg concentration of the Mg source is 1×10 19 cm -3 Up to 1×10 21 cm -3 .

[0012] Optionally, before epitaxially growing the n-type GaN layer on the substrate, the method includes: growing an AlN buffer layer on the substrate; and heat-treating the AlN buffer layer in a pure hydrogen atmosphere at a temperature of 1100° C. to 1200° C.

[0013] Optionally, after heat treating the AlN buffer layer in a pure hydrogen atmosphere, the step includes: growing a three-dimensional GaN buffer layer at a growth temperature of 1000° C. to 1100° C. and a growth pressure of 100 Torr to 500 Torr.

[0014] Optionally, the epitaxial growth of a p-type GaN layer on the pretreatment layer includes: introducing a Mg source into a reaction chamber, and growing a first p-type GaN layer at a growth temperature of 600°C to 800°C and a growth pressure of 200Torr to 500Torr; growing an electron blocking layer on the first p-type GaN layer at a growth temperature of 700°C to 1000°C and a growth pressure of 100Torr to 500Torr; introducing a Mg source into the reaction chamber, and growing a second p-type GaN layer on the electron blocking layer at a growth temperature of 800°C to 1000°C and a growth pressure of 200Torr to 600Torr; and growing a p-type contact layer on the second p-type GaN layer at a growth temperature of 850°C to 1000°C and a growth pressure of 100Torr to 300Torr.

[0015] On the other hand, the embodiment of the present disclosure also provides a GaN-based light-emitting diode epitaxial wafer, which includes an n-type GaN layer, a multi-quantum well layer, a pretreatment layer and a p-type GaN layer stacked in sequence on a substrate; the pretreatment layer is formed by intermittently introducing a Mg source into a reaction chamber in a pulsed manner, and the pretreatment layer is a Mg metal layer.

[0016] The beneficial effects brought by the technical solution provided by the embodiments of the present disclosure include at least:

[0017] The method for preparing a GaN-based light-emitting diode epitaxial wafer provided in the embodiment of the present disclosure epitaxially grows an n-type GaN layer and a multi-quantum well layer on a substrate, and then intermittently introduces a Mg source into a reaction chamber on the multi-quantum well layer in a pulsed manner to form a pretreatment layer on the multi-quantum well layer, and then epitaxially grows a p-type GaN layer on the pretreatment layer.

[0018] In this way, before growing the p-type GaN layer, the Mg source is pre-passed, and a certain amount of Cp2Mg is pre-attached to the cavity wall of the reaction chamber, so that when growing the p-type GaN layer heavily doped with Mg, more Cp2Mg can be deposited on the p-type GaN layer, thereby increasing the Mg concentration in the p-type GaN layer heavily doped with Mg, that is, increasing the hole concentration to increase the quantum efficiency of the chip. The pretreatment layer is a Mg metal layer, which can effectively increase the Mg doping concentration in the area near the multi-quantum well layer in the p-type GaN layer. In addition, the increase in the hole concentration in the p-type GaN layer grown after the Mg source is pre-passed causes the carriers to mainly concentrate on the quantum wells near the P-type GaN layer with poor crystal quality to emit light, thereby improving the luminous efficiency of the light-emitting diode chip and increasing the luminous intensity of the light-emitting diode chip.

[0019] In addition, the Mg source is pulsed to allow the Mg source to be intermittently introduced into the reaction chamber. Since clusters are prone to form during the deposition of Cp2Mg, the Mg source is intermittently introduced to allow Cp2Mg time to diffuse during the time when the Mg source is stopped, which is beneficial for Mg to evenly cover the surface of the multi-quantum well layer and form a uniform pretreatment layer, thereby reducing the formation of impurities by Mg source clusters that affect the quality of epitaxial wafer crystals, facilitating the doping of Mg during the subsequent growth of a p-type GaN layer, effectively increasing the actual doping concentration of Mg, increasing the hole concentration of the p-type GaN layer, and improving the luminous efficiency of the light-emitting diode chip. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0021] Figure 1 It is a structural schematic diagram of a GaN-based light-emitting diode epitaxial wafer provided in an embodiment of the present disclosure;

[0022] Figure 2 It is a flow chart of a method for preparing a GaN-based light-emitting diode epitaxial wafer provided in an embodiment of the present disclosure;

[0023] Figure 3 It is a flow chart of another method for preparing a GaN-based light-emitting diode epitaxial wafer provided in an embodiment of the present disclosure.

[0024] The descriptions of the marks in the figure are as follows:

[0025] 10. Substrate;

[0026] 21. n-type GaN layer; 22. AlN buffer layer; 23. three-dimensional GaN buffer layer; 24. GaN recovery layer;

[0027] 30. Multiple quantum well layer;

[0028] 40. Preprocessing layer;

[0029] 50. p-type GaN layer; 51. first p-type GaN layer; 52. electron blocking layer; 53. second p-type GaN layer; 54. p-type contact layer. DETAILED DESCRIPTION

[0030] In order to make the objectives, technical solutions and advantages of the present disclosure more clear, the embodiments of the present disclosure will be further described in detail below with reference to the accompanying drawings.

[0031] In the related art, GaN-based light-emitting diode epitaxial wafers generally include a substrate, an AlN buffer layer, an n-type GaN layer, a multi-quantum well layer, a p-type GaN layer, an electron blocking layer, and a p-type contact layer stacked in sequence. In order to increase the hole concentration of the p-type GaN layer, a Mg source is also introduced into the reaction chamber when growing the p-type GaN layer, and the introduced Mg source can be CP2Mg.

[0032] In the process of CP2Mg being transported to the reaction chamber, Cp2Mg is easily adsorbed on the transport pipe and the wall of the reaction chamber, which is the memory effect of Mg. This results in a lower actual Mg doping concentration in the p-type GaN layer and reduces the hole concentration in the p-type GaN layer, affecting the luminous efficiency of the LED chip.

[0033] To this end, an embodiment of the present disclosure provides a GaN-based light emitting diode epitaxial wafer. Figure 1 Schematic diagram of the structure of a GaN-based light-emitting diode epitaxial wafer provided by the embodiment of the present disclosure. Figure 1 As shown, the GaN-based light-emitting diode epitaxial wafer includes an n-type GaN layer 21 , a multi-quantum well layer 30 , a pretreatment layer 40 and a p-type GaN layer 50 which are sequentially stacked on a substrate 10 .

[0034] The pretreatment layer 40 is formed by intermittently introducing a Mg source into the reaction chamber in a pulsed manner, and the pretreatment layer 40 is a Mg metal layer.

[0035] The GaN-based light-emitting diode epitaxial wafer provided in the embodiment of the present disclosure is provided with a pretreatment layer 40 between the multi-quantum well layer 30 and the p-type GaN layer 50. The pretreatment layer 40 is formed on the multi-quantum well layer 30 by intermittently introducing a Mg source into the reaction chamber in a pulsed manner. Thus, before forming the p-type GaN layer 50, the Mg source is introduced in advance to attach a certain amount of Cp2Mg to the cavity wall of the reaction chamber in advance, so that when growing the heavily Mg-doped p-type GaN layer 50, more Cp2Mg can be deposited on the p-type GaN layer 50, thereby increasing the Mg concentration in the highly heavily Mg-doped p-type GaN layer 50 in the subsequent growth of the p-type GaN layer 50, that is, increasing the hole concentration, so as to increase the quantum efficiency of the chip.

[0036] In the disclosed embodiment, the p-type GaN layer generally includes a first sublayer, a second sublayer, and a third sublayer, the Mg doping concentrations of which decrease in sequence, and the first sublayer with the largest Mg doping concentration is close to the multi-quantum well layer. Since the first sublayer requires a higher Mg doping concentration, a pretreatment layer is formed before growing the first sublayer, which can effectively increase the Mg doping concentration of the first sublayer, that is, increase the Mg doping concentration of the region near the multi-quantum well layer 30 in the p-type GaN layer 50. The increase in the hole concentration in the p-type GaN layer 50 grown after the Mg source is pre-passed causes the carriers to mainly emit light in the quantum wells near the p-type GaN layer 50 with poor crystal quality, thereby improving the luminous efficiency of the light-emitting diode chip and improving the luminous intensity of the light-emitting diode chip.

[0037] In addition, the Mg source is pulsed to allow the Mg source to be intermittently introduced into the reaction chamber. Since clusters are prone to form during the deposition process of Cp2Mg, the Mg source is intermittently introduced to allow Cp2Mg time to diffuse during the time when the Mg source is stopped, which is beneficial for Mg to evenly cover the surface of the multi-quantum well layer 30 and form a uniform pretreatment layer 40, thereby reducing the formation of impurities by Mg source clusters that affect the quality of epitaxial wafer crystals, facilitating the subsequent growth of p-type GaN layer 50 during Mg doping, effectively increasing the actual Mg doping concentration, increasing the hole concentration of the p-type GaN layer 50, and improving the luminous efficiency of the light-emitting diode chip.

[0038] Optionally, the substrate 10 may be a sapphire substrate 10 .

[0039] It should be noted that the substrate 10 may also be a GaN flat sheet, a SiC flat sheet, or a Si flat sheet, and the embodiments of the present disclosure do not limit this.

[0040] In the present disclosure, Figure 1 As shown, a three-dimensional GaN buffer layer 23 and an undoped GaN recovery layer 24 are further included between the substrate 10 and the n-type GaN layer 21 and are sequentially stacked on the substrate 10 .

[0041] For example, the thickness of the AlN buffer layer 22 may be 10 mm to 50 mm. As an example, in the embodiment of the present disclosure, the thickness of the AlN buffer layer 22 may be 30 nm.

[0042] For example, the thickness of the three-dimensional GaN buffer layer 23 may be 1 μm to 5 μm. As an example, in the embodiment of the present disclosure, the thickness of the three-dimensional GaN buffer layer 23 is 3 μm.

[0043] For example, the thickness of the undoped GaN recovery layer 24 may be 1 μm to 5 μm. As an example, in the embodiment of the present disclosure, the thickness of the undoped GaN recovery layer 24 is 3 μm.

[0044] For example, the n-type GaN layer 21 is doped with Si, and the concentration of Si doping may be 1×10 18 Up to 1×10 19c m -3 .

[0045] Optionally, the thickness of the n-type GaN layer 21 may be 1 μm to 5 μm. For example, the thickness of the n-type GaN layer 21 may be 3 μm.

[0046] Optionally, the multi-quantum well layer 30 may include 5 to 11 periods of InGaN quantum well layers and GaN quantum barrier layers. The InGaN quantum well layers may be grown to a thickness of 2 nm to 3 nm; and the GaN quantum barrier layers may be grown to a thickness of 9 nm to 20 nm.

[0047] Optionally, the thickness of the pretreatment layer 40 may be 1 nm to 20 nm. As an example, in the embodiment of the present disclosure, the thickness of the pretreatment layer 40 is 5 nm.

[0048] In the present disclosure, Figure 1 As shown, the p-type GaN layer 50 includes: a first p-type GaN layer 51 , an electron blocking layer 52 , a second p-type GaN layer 53 and a p-type contact layer 54 which are sequentially stacked on the multi-quantum well layer 30 .

[0049] The first p-type GaN layer 51 is a low-temperature p-type GaN layer heavily doped with Mg, and the thickness of the first p-type GaN layer 51 may be 50 nm to 100 nm.

[0050] As an example, in the embodiment of the present disclosure, the thickness of the first p-type GaN layer 51 is 80 nm.

[0051] The first p-type GaN layer 51 can ensure that there are enough holes entering the multi-quantum well layer 30 to recombine with electrons, so as to ensure the light emitting efficiency of the light emitting diode.

[0052] For example, in the first p-type GaN layer 51, the doping concentration of Mg is 1×1020 cm -3 Up to 2×10 20 cm -3 .

[0053] Alternatively, the electron blocking layer 52 may be a p-type AlGaN electron blocking layer 52. The electron blocking layer 52 may have a thickness of 20 nm to 100 nm.

[0054] As an example, in the embodiment of the present disclosure, the thickness of the electron blocking layer 52 may be 30 nm.

[0055] The doping element in the p-type AlGaN electron blocking layer 52 may be Mg, and the doping concentration of Mg is less than 10 19 cm -3 The effect and quality of the electron blocking layer 52 can be guaranteed.

[0056] For example, the composition of Al in the p-type AlGaN electron blocking layer 52 may be controlled to be 10% to 30%.

[0057] Optionally, a second p-type GaN layer 53 of good quality can be grown on the p-type AlGaN electron blocking layer 52 , which can provide sufficient holes and have a relatively slight light absorption effect, thereby facilitating the improvement of the light emitting efficiency of the light emitting diode.

[0058] For example, the thickness of the second p-type GaN layer 53 may be 100 nm to 200 nm. As an example, in the embodiment of the present disclosure, the thickness of the second p-type GaN layer 53 may be 150 nm.

[0059] The doping element in the second p-type GaN layer 53 is Mg, and the doping concentration of Mg in the second p-type GaN layer 53 is 1×10 19 Up to 1×10 20 cm -3 At this time, a light-emitting diode with good luminous efficiency can be obtained.

[0060] Optionally, the thickness of the p-type contact layer 54 may be 10 nm to 50 nm. As an example, in the embodiment of the present disclosure, the thickness of the p-type contact layer 54 may be 30 nm.

[0061] Figure 2 The present invention provides a method for preparing a GaN-based light-emitting diode epitaxial wafer. Figure 1 The GaN-based light-emitting diode epitaxial wafer shown in FIG. Figure 2 As shown, the preparation method comprises:

[0062] S11: providing a substrate 10.

[0063] S12 : epitaxially growing an n-type GaN layer 21 on the substrate 10 .

[0064] S13 : epitaxially growing the multi-quantum well layer 30 on the n-type GaN layer 21 .

[0065] S14 : introducing a Mg source into the reaction chamber intermittently in a pulsed manner to form a pretreatment layer 40 on the multi-quantum well layer 30 .

[0066] Wherein, the pretreatment layer is a Mg metal layer.

[0067] S15 : epitaxially growing a p-type GaN layer 50 on the pre-treatment layer 40 .

[0068] The method for preparing a GaN-based light-emitting diode epitaxial wafer provided in the embodiment of the present disclosure is to epitaxially grow an n-type GaN layer 21 and a multi-quantum well layer 30 on a substrate 10, and then intermittently introduce a Mg source into a reaction chamber on the multi-quantum well layer 30 in a pulsed manner to form a pretreatment layer 40 on the multi-quantum well layer 30, and then epitaxially grow a p-type GaN layer 50 on the pretreatment layer 40.

[0069] In this way, before growing the p-type GaN layer 50, the Mg source is pre-connected, and a certain amount of Cp2Mg is pre-attached to the cavity wall of the reaction chamber, so that when growing the heavily Mg-doped p-type GaN layer 50, more Cp2Mg can be deposited on the p-type GaN layer 50, thereby increasing the Mg concentration in the heavily Mg-doped p-type GaN layer 50, that is, increasing the hole concentration, so as to increase the quantum efficiency of the chip. In addition, the increase in the hole concentration in the p-type GaN layer 50 grown after the Mg source is pre-connected makes the carriers mainly concentrate in the quantum wells near the p-type GaN layer 50 with poor crystal quality to emit light, thereby improving the luminous efficiency of the light-emitting diode chip and improving the luminous intensity of the light-emitting diode chip.

[0070] In addition, the Mg source is pulsed so that the Mg source is intermittently introduced into the reaction chamber, which is beneficial for Mg to evenly cover the surface of the multi-quantum well layer 30, form a uniform pretreatment layer 40, reduce the influence of impurities formed by Mg source clusters on the crystal quality of the epitaxial wafer, and facilitate the subsequent growth of the p-type GaN layer 50. The doping of Mg effectively increases the actual doping concentration of Mg, increases the hole concentration of the p-type GaN layer 50, and improves the luminous efficiency of the light-emitting diode chip.

[0071] Figure 3 FIG. 1 is a flow chart of another method for preparing a GaN-based light-emitting diode epitaxial wafer provided by an embodiment of the present disclosure. Figure 3 As shown, the preparation method comprises:

[0072] S21: providing a substrate 10.

[0073] Optionally, the substrate 10 is a sapphire substrate 10. Sapphire has a relatively high light transmittance, that is, the substrate 10 is a transparent substrate 10. In addition, the sapphire material is relatively hard and has relatively stable chemical properties, so that the red light emitting diode has good light emitting effect and stability.

[0074] In step S21, the sapphire substrate 10 may be pre-treated by placing the sapphire substrate 10 in a MOCVD (Metal-organic Chemical Vapor Deposition) reaction chamber and baking the sapphire substrate 10 for 12 to 18 minutes. As an example, in the embodiment of the present disclosure, the sapphire substrate 10 is baked for 15 minutes.

[0075] Specifically, the baking temperature may be 1000° C. to 1200° C., and the pressure in the MOCVD reaction chamber during baking may be 100 mbar to 200 mbar.

[0076] Step S22 : growing an AlN buffer layer 22 on the substrate 10 .

[0077] The step S22 may include placing the substrate 10 into a magnetron sputtering device to form an AlN buffer layer 22. The AlN buffer layer 22 grown in this manner has better quality.

[0078] For example, the temperature of the AlN buffer layer 22 during sputtering may be 600° C. to 800° C. During the growth of the AlN buffer layer 22 , the sputtering temperature of the AlN buffer layer 22 within the above range can obtain a high-quality AlN buffer layer 22 , thereby ensuring the quality of the light-emitting diode.

[0079] Optionally, the pressure during sputtering of the AlN buffer layer 22 may be 4 mTorr to 10 mTorr. Setting the sputtering pressure of the AlN buffer layer 22 within the above range can ensure that the quality of the obtained AlN buffer layer 22 is good, thereby ensuring the quality of the epitaxial layer grown on the AlN buffer layer 22, and ultimately improving the luminous efficiency of the light-emitting diode.

[0080] Optionally, the thickness of the AlN buffer layer 22 may be 10 nm to 50 nm. As an example, in the embodiment of the present disclosure, the thickness of the AlN buffer layer 22 is 30 nm.

[0081] Step S23: heat-treating the AlN buffer layer 22 in a pure hydrogen atmosphere at a temperature of 1100° C. to 1200° C.

[0082] Before the n-type GaN layer 21 is grown on the AlN buffer layer 22, the substrate 10 is placed in a metal organic chemical vapor deposition MOCVD; hydrogen is introduced into the MOCVD to perform a heat treatment on the AlN buffer layer 22 for 10 to 15 minutes. After the substrate 10 on which the AlN buffer layer 22 is grown is transferred to the MOCVD, the AlN buffer layer 22 is first subjected to a high-temperature heat treatment in a hydrogen atmosphere, which can remove some unstable AlN crystals on the surface of the AlN buffer layer 22, ensure the cleanliness of the AlN layer surface, and further ensure the quality of the epitaxial layer grown on the AlN buffer layer 22.

[0083] The heat treatment temperature is 1100° C. to 1200° C. Under this temperature condition, the AlN buffer layer 22 is heat treated to remove unstable single-crystal AlN crystals in the AlN buffer layer 22, and pits are formed on the surface of the AlN film away from the substrate 10, which is beneficial to promote the subsequent growth of the three-dimensional GaN buffer layer 23 and obtain a high-quality epitaxial layer.

[0084] Step S24 : growing a three-dimensional GaN buffer layer 23 on the AlN buffer layer 22 .

[0085] When growing the three-dimensional GaN buffer layer 23 , the growth temperature is controlled to be 1000° C. to 1100° C., and the growth pressure is controlled to be 100 Torr to 500 Torr.

[0086] Exemplarily, the three-dimensional GaN buffer layer 23 is grown under the conditions of a growth temperature of 1000° C. and a growth pressure of 300 Torr.

[0087] Step S25 : growing an undoped GaN recovery layer 24 on the three-dimensional GaN buffer layer 23 .

[0088] The growth temperature of the three-dimensional GaN buffer layer 23 may be 1000° C. to 1100° C., and the growth pressure may be 100 Torr to 500 Torr. Under these conditions, the quality of the three-dimensional GaN buffer layer 23 grown is good.

[0089] For example, the thickness of the undoped GaN recovery layer 24 may be 1 μm to 5 μm. As an example, in the embodiment of the present disclosure, the thickness of the GaN recovery layer 24 may be 3 μm.

[0090] Step S26 : epitaxially growing an n-type GaN layer 21 on the GaN recovery layer 24 .

[0091] The growth temperature of the n-type GaN layer 21 may be 1000° C. to 1200° C., and the growth pressure may be 100 Torr to 500 Torr.

[0092] For example, the n-type GaN layer 21 may be doped with Si, and the concentration of Si doping may be 1×10 18 Up to 1×10 19 cm -3 .

[0093] For example, the growth thickness of the n-type GaN layer 21 may be 1 μm to 5 μm. As an example, in the embodiment of the present disclosure, the growth thickness of the n-type GaN layer 21 is 3 μm.

[0094] Step S27 : epitaxially growing a multi-quantum well layer 30 on the n-type GaN layer 21 .

[0095] Optionally, in step S27 , the multi-quantum well layer 30 may include 5 to 11 periods of InGaN quantum well layers and GaN quantum barrier layers.

[0096] Among them, the growth temperature of the InGaN quantum well layer can be 720℃ to 829℃, the growth pressure of the InGaN quantum well layer can be 100Torr to 500Torr, and the growth thickness of the InGaN quantum well layer can be 2min to 3nm; the growth temperature of the GaN quantum barrier layer can be 850℃ to 959℃, the growth pressure of the GaN quantum barrier layer can be 100Torr to 500Torr, and the growth thickness of the GaN quantum barrier layer can be 9nm to 20nm.

[0097] Step S28 : intermittently introducing a Mg source into the reaction chamber in a pulsed manner to form a pretreatment layer 40 on the multi-quantum well layer 30 .

[0098] The pretreatment layer 40 is a Mg metal layer.

[0099] Optionally, when the Mg source is introduced in a pulsed manner, the ratio of the time for introducing the Mg source to the time for stopping the introduction of the Mg source is controlled to be 3:1 to 10:1.

[0100] In this way, the ratio of the time for introducing the Mg source to the time for stopping the introduction of the Mg source is controlled to be within this range, so that the Mg source is intermittently introduced into the reaction chamber, which is conducive to uniform coverage of the surface of the multi-quantum well layer 30 by Mg, forming a uniform pretreatment layer 40, reducing the influence of impurities formed by Mg source clusters on the crystal quality of the epitaxial wafer, and facilitating the subsequent growth of the p-type GaN layer 50. The doping of Mg can effectively increase the actual doping concentration of Mg, increase the hole concentration of the p-type GaN layer 50, and improve the luminous efficiency of the light-emitting diode chip.

[0101] Exemplarily, when the Mg source is controlled to be introduced into the reaction chamber in a pulsed manner, when the ratio of the time of introducing the Mg source to the time of stopping the introduction of the Mg source is 5:1 to 8:1, a more uniform pretreatment layer 40 can be formed, so that Mg evenly covers the surface of the n-type GaN layer 21, reducing the influence of impurities formed by Mg source clusters on the crystal quality of the epitaxial wafer.

[0102] As an example, in the embodiment of the present disclosure, the ratio of the time for introducing the Mg source to the time for stopping the introduction of the Mg source may be 6:1.

[0103] In the embodiment of the present disclosure, the number of interruptions in introducing the Mg source may be no less than 2 times. In this way, when the Mg source is introduced, the Mg source is intermittently introduced into the reaction chamber through multiple intermittent pre-passes, which is beneficial for Mg to uniformly cover the surface of the multi-quantum well layer 30 and form a uniform pretreatment layer 40.

[0104] Optionally, the total time of introducing the Mg source is 60s to 1000s. The total time of introducing the Mg source is controlled within this range to avoid the total time of introducing the Mg source being too short to form a uniform pretreatment layer 40, which is not conducive to the subsequent growth of the p-type GaN layer 50. It can also avoid the total time of introducing the Mg source being too long, which will lead to an increase in the cost of the epitaxial wafer.

[0105] Exemplarily, the total time for the Mg source to be introduced into the reaction chamber may be 500 s to 600 s. For example, the total time for the Mg source to be introduced into the reaction chamber may be 600 s.

[0106] Optionally, when the Mg source is introduced, the temperature in the reaction chamber is controlled to be 700° C. to 800° C.

[0107] Exemplarily, when the temperature of the pre-Mg source passing into the reaction chamber is 700° C. to 780° C., a more uniform pre-treatment layer 40 can be formed, thereby reducing the influence of impurities formed by Mg source clusters on the crystal quality of the epitaxial wafer.

[0108] As an example, in the embodiment of the present disclosure, the temperature of the pre-Mg source to the reaction chamber is 750°C.

[0109] Optionally, when the Mg source is introduced, the pressure in the reaction chamber is controlled to be 200 Torr to 600 Torr.

[0110] Exemplarily, when the pressure of the Mg source pre-passed into the reaction chamber is 300 Torr to 500 Torr, a more uniform pre-treatment layer 40 can be formed, and the influence of impurities formed by Mg source clusters on the crystal quality of the epitaxial wafer can be reduced.

[0111] As an example, in the embodiment of the present disclosure, the pressure of the Mg source pre-passed into the reaction chamber is 500 Torr.

[0112] Optionally, the Mg concentration of the Mg source is 1×10 19 cm -3 Up to 1×10 21 cm -3 .

[0113] For example, the Mg concentration of the Mg source is 1×10 20 cm-3 Up to 1×10 21 cm -3 When the pretreatment layer 40 is formed more uniformly, the influence of impurities formed by Mg source clusters on the crystal quality of the epitaxial wafer is reduced.

[0114] As an example, in the embodiment of the present disclosure, the Mg concentration of the Mg source is 1×10 20 cm -3 .

[0115] Step S29 : epitaxially growing a p-type GaN layer 50 on the pretreatment layer 40 .

[0116] In the embodiment of the present disclosure, epitaxial growth of the p-type GaN layer 50 may include the following steps.

[0117] In the first step, a Mg source is introduced into the reaction chamber to grow the first p-type GaN layer 51 at a growth temperature of 600° C. to 800° C. and a growth pressure of 200 Torr to 500 Torr.

[0118] Exemplarily, the first p-type GaN layer 51 is grown under the conditions of a growth temperature of 700° C. and a growth pressure of 300 Torr.

[0119] The first p-type GaN layer 51 is a low-temperature p-type GaN layer heavily doped with Mg, and the thickness of the first p-type GaN layer 51 may be 50 nm to 100 nm.

[0120] As an example, in the embodiment of the present disclosure, the thickness of the first p-type GaN layer 51 is 80 nm.

[0121] The first p-type GaN layer 51 can ensure that there are enough holes entering the multi-quantum well layer 30 to recombine with electrons, so as to ensure the light emitting efficiency of the light emitting diode.

[0122] For example, in the first p-type GaN layer 51, the doping concentration of Mg is 1×10 20 cm -3 Up to 2×10 20 cm -3 .

[0123] In the second step, an electron blocking layer 52 is grown on the first p-type GaN layer 51 at a growth temperature of 700° C. to 1000° C. and a growth pressure of 100 Torr to 500 Torr.

[0124] Exemplarily, the electron blocking layer 52 is grown under the conditions of a growth temperature of 800° C. and a growth pressure of 300 Torr.

[0125] Alternatively, the electron blocking layer 52 may be a p-type AlGaN electron blocking layer 52. The electron blocking layer 52 may have a thickness of 20 nm to 100 nm.

[0126] As an example, in the embodiment of the present disclosure, the thickness of the electron blocking layer 52 may be 30 nm.

[0127] The doping element in the p-type AlGaN electron blocking layer 52 may be Mg, and the doping concentration of Mg is less than 10 19 cm -3 The effect and quality of the electron blocking layer 52 can be guaranteed.

[0128] For example, the composition of Al in the p-type AlGaN electron blocking layer 52 may be controlled to be 10% to 30%.

[0129] Optionally, a second p-type GaN layer 53 of good quality can be grown on the p-type AlGaN electron blocking layer 52 , which can provide sufficient holes and have a relatively slight light absorption effect, thereby facilitating the improvement of the light emitting efficiency of the light emitting diode.

[0130] In the third step, a Mg source is introduced into the reaction chamber, and a second p-type GaN layer 53 is grown on the electron blocking layer 52 at a growth temperature of 800° C. to 1000° C. and a growth pressure of 200 Torr to 600 Torr.

[0131] Exemplarily, the second p-type GaN layer 53 is grown under the conditions of a growth temperature of 900° C. and a growth pressure of 500 Torr.

[0132] For example, the thickness of the second p-type GaN layer 53 may be 100 nm to 200 nm. As an example, in the embodiment of the present disclosure, the thickness of the second p-type GaN layer 53 may be 150 nm.

[0133] The doping element in the second p-type GaN layer 53 is Mg, and the doping concentration of Mg in the second p-type GaN layer 53 is 1×10 19 Up to 1×10 20 cm -3 At this time, a light-emitting diode with good luminous efficiency can be obtained.

[0134] In the fourth step, a p-type contact layer 54 is grown on the second p-type GaN layer 53 at a growth temperature of 850° C. to 1000° C. and a growth pressure of 100 Torr to 300 Torr.

[0135] Exemplarily, the p-type contact layer 54 is grown under the conditions of a growth temperature of 900° C. and a growth pressure of 200 Torr.

[0136] Optionally, the thickness of the p-type contact layer 54 may be 10 nm to 50 nm. As an example, in the embodiment of the present disclosure, the thickness of the p-type contact layer 54 may be 30 nm.

[0137] After executing step S29, the epitaxial wafer may be annealed in a nitrogen atmosphere, wherein the annealing temperature is 650° C. to 850° C. and the annealing time is 5 min to 15 min.

[0138] The above description is only an optional embodiment of the present disclosure and is not intended to limit the present disclosure. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present disclosure shall be included in the protection scope of the present disclosure.

Claims

1. A method for preparing a GaN-based light-emitting diode epitaxial wafer, characterized in that: The preparation method comprises: providing a substrate; epitaxially growing an n-type GaN layer on the substrate; epitaxially growing a multi-quantum well layer on the n-type GaN layer; A Mg source is intermittently introduced into the reaction chamber in a pulsed manner to form a pretreatment layer on the multi-quantum well layer, wherein the pretreatment layer is a Mg metal layer; when the Mg source is introduced in a pulsed manner, the ratio of the time for introducing the Mg source to the time for stopping introducing the Mg source is controlled to be 3:1 to 10:1, the total time for introducing the Mg source is 60s to 1000s, when the Mg source is introduced, the temperature in the reaction chamber is controlled to be 700°C to 800°C, when the Mg source is introduced, the pressure in the reaction chamber is controlled to be 200Torr to 600Torr, and the Mg concentration of the introduced Mg source is 1×10 19 cm -3 Up to 1×10 21 cm -3 ; A p-type GaN layer is epitaxially grown on the pretreated layer.

2. The preparation method according to claim 1, characterized in that: Before epitaxially growing an n-type GaN layer on the substrate, the method comprises: growing an AlN buffer layer on the substrate; The AlN buffer layer is heat-treated in a pure hydrogen atmosphere at a temperature of 1100° C. to 1200° C.

3. The preparation method according to claim 2, characterized in that: After the AlN buffer layer is heat treated in a pure hydrogen atmosphere, the method further comprises: A three-dimensional GaN buffer layer is grown under the conditions of a growth temperature of 1000° C. to 1100° C. and a growth pressure of 100 Torr to 500 Torr.

4. The preparation method according to claim 1, characterized in that: The epitaxial growth of a p-type GaN layer on the pre-treated layer comprises: A Mg source is introduced into the reaction chamber to grow a first p-type GaN layer at a growth temperature of 600° C. to 800° C. and a growth pressure of 200 Torr to 500 Torr; Under the conditions of a growth temperature of 700° C. to 1000° C. and a growth pressure of 100 Torr to 500 Torr, growing an electron blocking layer on the first p-type GaN layer; Introducing a Mg source into a reaction chamber, and growing a second p-type GaN layer on the electron blocking layer at a growth temperature of 800° C. to 1000° C. and a growth pressure of 200 Torr to 600 Torr; A p-type contact layer is grown on the second p-type GaN layer at a growth temperature of 850° C. to 1000° C. and a growth pressure of 100 Torr to 300 Torr.

5. A GaN-based light-emitting diode epitaxial wafer, characterized in that: The GaN-based light-emitting diode epitaxial wafer is prepared by the preparation method according to any one of claims 1 to 4, and the GaN-based light-emitting diode epitaxial wafer comprises an n-type GaN layer (21), a multi-quantum well layer (30), a pretreatment layer (40) and a p-type GaN layer (50) which are sequentially stacked on a substrate (10); The pretreatment layer (40) is formed by intermittently introducing a Mg source into a reaction chamber in a pulsed manner, and the pretreatment layer (40) is a Mg metal layer.

Images