Preparation method of ultraviolet light-emitting diode epitaxial wafer with increased hole quantity and epitaxial wafer

Abstract

The present disclosure provides a method for preparing an ultraviolet light-emitting diode epitaxial wafer and an epitaxial wafer with increased hole content, belonging to the field of semiconductor device technology. An AlGaN composite layer is periodically grown on the active layer to obtain a P-type AlGaN layer, and the AlGaN composite layer includes an AlGaN three-dimensional sublayer, an AlGaN capping sublayer, and an AlGaN processing sublayer stacked in sequence. Reduce internal stress and defects. The nitrogen-rich AlGaN three-dimensional sublayer is more easily doped with more Mg elements, thereby increasing the hole content. The distribution of Al atoms and Ga atoms in a low-nitrogen environment is more uniform, ensuring the crystal quality of the final AlGaN composite layer. Finally, only ammonia gas is introduced into the reaction chamber to grow the AlGaN processing sublayer. It is ensured that the final P-type AlGaN layer can provide a large number of holes while ensuring the crystal quality of the final P-type AlGaN layer.

Description

Technical Field

[0001] The present disclosure relates to the technical field of semiconductor devices, and in particular to a method for preparing an ultraviolet light-emitting diode epitaxial wafer with increased hole content and an epitaxial wafer. Background Art

[0002] With the development of LED applications, the market demand for ultraviolet (UV) LEDs is growing. UV LEDs, with a wavelength range of 210-400nm, offer unparalleled advantages over traditional UV light sources. UV LEDs are commonly used in lighting, biomedicine, anti-counterfeiting, air and water purification, biochemical testing, and high-density information storage. UV LED epitaxial wafers are the foundation for their fabrication. These wafers consist of a substrate, an N-type AlGaN layer, an active layer, and a P-type AlGaN layer stacked sequentially on top of the substrate.

[0003] Due to the large band gap of the AlGaN material itself, the donor / acceptor energy levels between the band gaps deepen, and the ionization energy of the dopant also increases, resulting in very low activation rates of the doped elements and carrier concentrations. Furthermore, the activation energy of the Mg acceptor doped in the P-type AlGaN layer is relatively high, reaching 500-600 meV. This results in a very low activation rate of Mg in the P-type AlGaN layer. This very low activation rate of Mg directly affects the amount of holes in the P-type AlGaN layer, resulting in low luminous efficiency of the resulting UV light-emitting diode. Summary of the Invention

[0004] The present disclosure provides a method for preparing an ultraviolet light-emitting diode epitaxial wafer with increased hole content and an epitaxial wafer, which can increase the hole content to improve the light extraction efficiency of the obtained ultraviolet light-emitting diode epitaxial wafer. The technical solution is as follows:

[0005] The present disclosure provides a method for preparing an ultraviolet light-emitting diode epitaxial wafer with increased hole content, the method comprising:

[0006] providing a substrate;

[0007] sequentially growing an N-type AlGaN layer and an active layer on the substrate;

[0008] Periodically growing an AlGaN composite layer on the active layer to obtain a P-type AlGaN layer, wherein the AlGaN composite layer includes an AlGaN three-dimensional sublayer, an AlGaN cap sublayer, and an AlGaN treatment sublayer stacked in sequence, and the AlGaN three-dimensional sublayer includes a plurality of AlGaN island structures stacked on the active layer or on the AlGaN composite layer;

[0009] The growing of the AlGaN composite layer comprises:

[0010] Introducing ammonia, Ga source, Al source, and Mg source into the reaction chamber to grow the AlGaN three-dimensional sublayer, wherein the flow ratio of the ammonia to the Ga source is 1000-2000, and the flow ratio of the ammonia to the Al source is 500-1000;

[0011] Introducing ammonia, Ga source, Al source, and Mg source into the reaction chamber to grow the AlGaN capping sublayer, wherein the flow ratio of the ammonia to the Ga source is 100-200, and the flow ratio of the ammonia to the Al source is 50-100;

[0012] Only ammonia gas is introduced into the reaction chamber to grow the AlGaN treatment sublayer.

[0013] Optionally, when growing the AlGaN three-dimensional sub-layer, ammonia with a flow rate of 100-200 slm, a Ga source with a flow rate of 0.05-0.2 slm, and an Al source with a flow rate of 0.1-0.4 slm are respectively introduced into the reaction chamber.

[0014] Optionally, when growing the AlGaN capping sublayer, ammonia with a flow rate of 10-20 slm, a Ga source with a flow rate of 0.05-0.2 slm, and an Al source with a flow rate of 0.1-0.4 slm are respectively introduced into the reaction chamber.

[0015] Optionally, the thickness of the AlGaN three-dimensional sublayer is less than or equal to the thickness of the AlGaN capping sublayer, and the thickness of the AlGaN three-dimensional sublayer is greater than the thickness of the AlGaN processing sublayer.

[0016] Optionally, the thickness of the AlGaN three-dimensional sublayer is 50-100 nm, the thickness of the AlGaN capping sublayer is 50-100 nm, and the thickness of the AlGaN processing sublayer is 10-30 nm.

[0017] Optionally, the growth time of the AlGaN treatment sublayer is 30-50s.

[0018] Optionally, the growth temperature and growth pressure of the AlGaN three-dimensional sub-layer are respectively equal to the growth temperature and growth pressure of the AlGaN capping sub-layer.

[0019] Optionally, the growth temperature and growth pressure of the AlGaN three-dimensional sub-layer are 850° C.-1050° C. and 100-200 Torr, respectively.

[0020] Optionally, the flow rate of the Mg source introduced during the growth of the AlGaN three-dimensional sub-layer is greater than the flow rate of the Mg source introduced during the growth of the AlGaN capping sub-layer.

[0021] An embodiment of the present disclosure provides an ultraviolet light-emitting diode epitaxial wafer with increased hole content. The ultraviolet light-emitting diode epitaxial wafer with increased hole content is prepared using the method for preparing an ultraviolet light-emitting diode epitaxial wafer with increased hole content as described above. The ultraviolet light-emitting diode epitaxial wafer with increased hole content includes a substrate and an N-type AlGaN layer, an active layer, and a P-type AlGaN layer sequentially stacked on the substrate. The P-type AlGaN layer includes periodically stacked AlGaN composite layers, and each of the AlGaN composite layers includes sequentially stacked AlGaN three-dimensional sublayers, AlGaN capping sublayers, and AlGaN processing sublayers.

[0022] The technical solutions provided by the embodiments of the present disclosure bring beneficial effects including:

[0023] An AlGaN composite layer is periodically grown on the active layer to obtain a P-type AlGaN layer. The AlGaN composite layer includes a sequentially stacked AlGaN three-dimensional sublayer, an AlGaN capping sublayer, and an AlGaN treatment sublayer. The P-type AlGaN layer itself has a periodically stacked structure, which is beneficial for stress release in the P-type AlGaN layer itself, reducing the internal stress and strain of the P-type AlGaN layer to reduce defects and improve the crystal quality of the resulting P-type AlGaN layer. The reduction in defects can promote the movement of holes and reduce the probability of holes being captured by defects. In the process of growing the AlGaN three-dimensional sublayers of the AlGaN composite layer, ammonia, Ga source, Al source, and Mg source are introduced into the reaction chamber to grow the AlGaN three-dimensional sublayers. The flow ratio of ammonia to Ga source is 1000-2000, and the flow ratio of ammonia to Al source is 500-1000. A nitrogen-rich AlGaN three-dimensional sublayer including multiple AlGaN island structures stacked on the active layer or on the AlGaN composite layer can be obtained. The AlGaN three-dimensional sublayer exists in an island-like structure. The surface of the AlGaN three-dimensional sublayer is more easily doped with Mg, promoting Mg doping to increase the amount of holes available at the bottom of the P-type AlGaN layer. An AlGaN capping sublayer is further grown on the AlGaN three-dimensional layer. During the growth of the AlGaN capping sublayer, the flow ratio of ammonia to Ga source is 100-200, and the flow ratio of ammonia to Al source is 50-100. On the one hand, this can effectively reduce the defects caused by large amounts of Mg doping. On the other hand, in a low-nitrogen environment, the viscosity of ammonia to Al and Ga atoms is reduced, making it easier for Al and Ga atoms in the AlGaN capping sublayer to reach the optimal nucleation position for stable growth. The distribution of Al and Ga atoms is more uniform, ensuring the crystal quality of the resulting AlGaN composite layer. Finally, only ammonia is introduced into the reaction chamber to grow the AlGaN treatment sublayer. This can react with excess Ga or Al atoms in the reaction chamber, preventing the excessive Ga and Al atoms from forming metal droplets on the surface of the epitaxial layer and reducing the absorption of holes by the metal droplets. It can ensure that the finally obtained P-type AlGaN layer can provide a large number of holes while ensuring the crystal quality of the finally obtained P-type AlGaN layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure, the following briefly introduces the drawings required for use in the description of the embodiments. 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 any creative work.

[0025] Figure 1 This is a flow chart of a method for preparing an ultraviolet light-emitting diode epitaxial wafer with increased hole content provided by an embodiment of the present disclosure;

[0026] Figure 2 This is a schematic structural diagram of an ultraviolet light-emitting diode epitaxial wafer with increased hole content provided by an embodiment of the present disclosure;

[0027] Figure 3 This is a flow chart of another method for preparing an ultraviolet light-emitting diode epitaxial wafer with increased hole content provided by an embodiment of the present disclosure;

[0028] Figure 4 This is a schematic structural diagram of another ultraviolet light-emitting diode epitaxial wafer with increased hole content provided by an embodiment of the present disclosure. DETAILED DESCRIPTION

[0029] 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.

[0030] Figure 1 This is a flow chart of a method for preparing an ultraviolet light-emitting diode epitaxial wafer with increased hole content provided by the embodiment of the present disclosure. Figure 1 It can be seen that the embodiment of the present disclosure provides a method for preparing an ultraviolet light-emitting diode epitaxial wafer with increased hole content, and the method for preparing an ultraviolet light-emitting diode epitaxial wafer with increased hole content includes:

[0031] S101: providing a substrate.

[0032] S102: Growing an N-type AlGaN layer and an active layer sequentially on the substrate.

[0033] S103: Periodically growing an AlGaN composite layer on the active layer to obtain a P-type AlGaN layer, the AlGaN composite layer including an AlGaN three-dimensional sublayer, an AlGaN capping sublayer and an AlGaN treatment sublayer stacked in sequence, the AlGaN three-dimensional sublayer including a plurality of AlGaN island structures stacked on the active layer or on the AlGaN composite layer; growing the AlGaN composite layer, including: introducing ammonia, a Ga source, an Al source and a Mg source into a reaction chamber to grow the AlGaN three-dimensional sublayer, wherein the flow ratio of ammonia to the Ga source is 1000-2000, and the flow ratio of ammonia to the Al source is 500-1000; introducing ammonia, a Ga source, an Al source and a Mg source into the reaction chamber to grow the AlGaN capping sublayer, wherein the flow ratio of ammonia to the Ga source is 100-200, and the flow ratio of ammonia to the Al source is 50-100; and introducing only ammonia into the reaction chamber to grow the AlGaN treatment sublayer.

[0034] An AlGaN composite layer is periodically grown on the active layer to obtain a P-type AlGaN layer. The AlGaN composite layer includes a sequentially stacked AlGaN three-dimensional sublayer, an AlGaN capping sublayer, and an AlGaN treatment sublayer. The P-type AlGaN layer itself has a periodically stacked structure, which is beneficial for stress release in the P-type AlGaN layer itself, reducing the internal stress and strain of the P-type AlGaN layer to reduce defects and improve the crystal quality of the resulting P-type AlGaN layer. The reduction in defects can promote the movement of holes and reduce the probability of holes being captured by defects. In the process of growing the AlGaN three-dimensional sublayers of the AlGaN composite layer, ammonia, Ga source, Al source, and Mg source are introduced into the reaction chamber to grow the AlGaN three-dimensional sublayers. The flow ratio of ammonia to Ga source is 1000-2000, and the flow ratio of ammonia to Al source is 500-1000. A nitrogen-rich AlGaN three-dimensional sublayer including multiple AlGaN island structures stacked on the active layer or on the AlGaN composite layer can be obtained. The AlGaN three-dimensional sublayer exists in an island-like structure. The surface of the AlGaN three-dimensional sublayer is more easily doped with Mg, promoting Mg doping to increase the amount of holes available at the bottom of the P-type AlGaN layer. An AlGaN capping sublayer is further grown on the AlGaN three-dimensional layer. During the growth of the AlGaN capping sublayer, the flow ratio of ammonia to Ga source is 100-200, and the flow ratio of ammonia to Al source is 50-100. On the one hand, this can effectively reduce the defects caused by large amounts of Mg doping. On the other hand, in a low-nitrogen environment, the viscosity of ammonia to Al and Ga atoms is reduced, making it easier for Al and Ga atoms in the AlGaN capping sublayer to reach the optimal nucleation position for stable growth. The distribution of Al and Ga atoms is more uniform, ensuring the crystal quality of the resulting AlGaN composite layer. Finally, only ammonia is introduced into the reaction chamber to grow the AlGaN treatment sublayer. This can react with excess Ga or Al atoms in the reaction chamber, preventing the excessive Ga and Al atoms from forming metal droplets on the surface of the epitaxial layer and reducing the absorption of holes by the metal droplets. This ensures that the resulting P-type AlGaN layer can provide a large number of holes while also ensuring the crystal quality of the resulting P-type AlGaN layer. Furthermore, the addition of the AlGaN treatment sublayer not only improves the quality of the resulting P-type AlGaN layer, but also plays a role in cleaning the gas environment within the reaction chamber, eliminating the need for gas scrubbing within the reaction chamber and reducing the production cost of ultraviolet light-emitting diodes.

[0035] It should be noted that, in the implementation provided by the present disclosure, the AlGaN capping sublayer covers the so-called portion of the AlGaN three-dimensional sublayer away from a surface of the substrate.

[0036] Optionally, in step S103 , when growing the AlGaN three-dimensional sub-layer, ammonia with a flow rate of 100-200 slm, a Ga source with a flow rate of 0.05-0.2 slm, and an Al source with a flow rate of 0.1-0.4 slm are respectively introduced into the reaction chamber.

[0037] During the growth of the AlGaN three-dimensional sublayer, the flow rates of ammonia, Ga source, and Al source are respectively within the above ranges, which can ensure that the quality of the obtained AlGaN three-dimensional sublayer is good. In addition, the AlGaN three-dimensional sublayer is also convenient for doping with Mg atoms during the growth process, which can increase the amount of holes in the final P-type AlGaN layer, thereby increasing the number of holes that can enter the active layer and recombine with electrons for light emission, and ultimately improve the luminous efficiency of the obtained ultraviolet light-emitting diode.

[0038] Optionally, in step S103 , when growing the AlGaN capping sublayer, ammonia with a flow rate of 10-20 slm, a Ga source with a flow rate of 0.05-0.2 slm, and an Al source with a flow rate of 0.1-0.4 slm are respectively introduced into the reaction chamber.

[0039] When growing the AlGaN capping sublayer, the flow rates of ammonia, Ga source, and Al source are respectively within the above ranges, which can obtain an AlGaN capping sublayer of good quality and smoother surface quality, thereby improving the crystal quality of the ultimately obtained P-type AlGaN layer and ensuring good quality of the obtained UV light-emitting diode epitaxial wafer.

[0040] Exemplarily, the flow rate of the Mg source introduced during the growth of the AlGaN three-dimensional sub-layer is greater than the flow rate of the Mg source introduced during the growth of the AlGaN capping sub-layer.

[0041] In the growth formation of the AlGaN three-dimensional sublayer and the AlGaN capping sublayer, the flow rate of the Mg source introduced into the AlGaN three-dimensional sublayer is greater than the strength of the Mg source introduced into the AlGaN capping sublayer during the growth formation, which can ensure a large amount of Mg doping in the AlGaN three-dimensional sublayer, so as to ensure that the P-type AlGaN layer can stably provide a large number of holes. In addition, while the Mg doping in the AlGaN capping sublayer can provide a certain amount of holes, the quality of the AlGaN capping sublayer itself is good, which can control the quality of the epitaxial material grown on the AlGaN capping sublayer and facilitate the subsequent formation of ohmic contact with the electrode, thereby reducing the contact resistance of the resulting ultraviolet light-emitting diode and thus reducing the operating voltage of the resulting ultraviolet light-emitting diode.

[0042] Optionally, during the growth of the AlGaN three-dimensional sublayer, the flow rate of the Mg source introduced into the reaction chamber is 1500-2000 sccm, and during the growth of the AlGaN capping sublayer, the flow rate of the Mg source introduced into the reaction chamber is 1500-2000 sccm.

[0043] During the growth of the AlGaN three-dimensional sublayer and the AlGaN capping sublayer, the flow rate of the introduced Mg source is within the above ranges, which can ensure that the obtained AlGaN three-dimensional sublayer and the AlGaN capping sublayer can provide sufficient holes. At the same time, it can also ensure that the crystal quality of the final P-type AlGaN layer is good and can be applied to most ultraviolet light-emitting diode epitaxial wafers of different thickness specifications.

[0044] Optionally, in step S103 , the thickness of the AlGaN three-dimensional sublayer is less than or equal to the thickness of the AlGaN capping sublayer, and the thickness of the AlGaN three-dimensional sublayer is greater than the thickness of the AlGaN processing sublayer.

[0045] The thickness of the AlGaN three-dimensional sublayer is less than or equal to the thickness of the AlGaN capping sublayer, and the thickness of the AlGaN three-dimensional sublayer is greater than the thickness of the AlGaN processing sublayer, which can ensure that the AlGaN three-dimensional sublayer can provide sufficient holes and that the AlGaN capping sublayer can effectively improve the overall quality of the AlGaN composite layer. At the same time, the thickness of the AlGaN processing sublayer is relatively small, which will not excessively increase the preparation cost of the ultraviolet light-emitting diode epitaxial wafer while also effectively improving the crystal quality of the P-type AlGaN layer.

[0046] It should be noted that the sum of the thickness of the AlGaN capping sublayer and the thickness of the AlGaN processing sublayer is greater than that of the AlGaN three-dimensional sublayer.

[0047] Optionally, in step S103 , the thickness of the AlGaN three-dimensional sub-layer is 50-100 nm, the thickness of the AlGaN capping sub-layer is 50-100 nm, and the thickness of the AlGaN processing sub-layer is 10-30 nm.

[0048] The thickness of each sub-layer in the AlGaN composite layer is respectively within the above ranges, which can ensure the quality of the obtained AlGaN composite layer while not significantly increasing the preparation cost of the ultraviolet light emitting diode.

[0049] Optionally, in step S103 , the growth time of the AlGaN treatment sublayer is 30-50 seconds.

[0050] The growth time of the AlGaN treatment sublayer is within the above range, which can ensure that the quality of the obtained AlGaN treatment sublayer is good, and the excessive Ga atoms and Al atoms in the reaction chamber are more fully processed, which can improve the crystal quality of the obtained P-type AlGaN layer without significantly increasing the cost of preparing ultraviolet light-emitting diodes.

[0051] Optionally, in step S103 , the growth temperature and growth pressure of the AlGaN three-dimensional sub-layer are respectively equal to the growth temperature and growth pressure of the AlGaN capping sub-layer.

[0052] The growth temperature and growth pressure of the AlGaN three-dimensional sublayer are respectively equal to the growth temperature and growth pressure of the AlGaN capping sublayer, which can ensure the quality of the obtained P-type AlGaN layer while not requiring many adjustments to the growth environment in the reaction chamber, thereby reducing the preparation cycle and preparation cost of the ultraviolet light-emitting diode epitaxial wafer.

[0053] It should be noted that the growth temperature and growth pressure of the AlGaN treatment sublayer may also be equal to the growth temperature and growth pressure of the AlGaN three-dimensional sublayer, respectively, which is not limited in the present disclosure.

[0054] Optionally, the growth temperature and growth pressure of the AlGaN three-dimensional sub-layer are 850° C.-1050° C. and 100-200 Torr, respectively.

[0055] The growth temperature and growth pressure of the AlGaN three-dimensional sublayer are respectively within the above ranges, which can ensure good growth quality of the obtained AlGaN three-dimensional sublayer and improve the crystal quality of the ultimately obtained P-type AlGaN.

[0056] Figure 2 This is a schematic structural diagram of an ultraviolet light-emitting diode epitaxial wafer with increased hole content provided by an embodiment of the present disclosure. Figure 2 The UV LED epitaxial wafer shown in the figure can be made of Figure 1 The method for preparing the ultraviolet light emitting diode epitaxial wafer is obtained by referring to Figure 2 It can be seen that the ultraviolet light-emitting diode epitaxial wafer with increased hole content is prepared by the above-mentioned method for preparing the ultraviolet light-emitting diode epitaxial wafer with increased hole content. The ultraviolet light-emitting diode epitaxial wafer with increased hole content includes a substrate 1 and an N-type AlGaN layer 2, an active layer 3 and a P-type AlGaN layer 4 stacked in sequence on the substrate 1. The P-type AlGaN layer 4 includes a periodically stacked AlGaN composite layer 41, and each AlGaN composite layer 41 includes an AlGaN three-dimensional sublayer 411, an AlGaN capping sublayer 412 and an AlGaN processing sublayer 413 stacked in sequence.

[0057] Figure 2 The technical effects of the UV LED epitaxial wafer shown in the figure can be referred to Figure 1 The technical effects of the method for preparing ultraviolet light-emitting diodes are shown in , so they will not be described here in detail.

[0058] Optionally, the entire thickness of the P-type AlGaN layer 4 may be 100-300 nm.

[0059] The overall thickness of the P-type AlGaN layer 4 is within the above range, which can provide a large number of holes without excessively increasing the preparation cost of the ultraviolet light-emitting diode epitaxial wafer. In addition, the light absorption effect of the P-type AlGaN layer 4 will not be too serious, which can ensure that the luminous efficiency of the final ultraviolet light-emitting diode epitaxial wafer is greatly improved.

[0060] For example, the thickness of the AlGaN composite layer 41 may be 50-100 nm, and the number of periods of the AlGaN composite layer 41 may be 3-6.

[0061] When the thickness and period number of the AlGaN composite layer 41 are within the above ranges, the obtained P-type AlGaN layer 4 has fewer defects, and the P-type AlGaN layer 4 itself can also provide a large number of holes, thereby ensuring that the light extraction efficiency of the final ultraviolet light emitting diode is improved.

[0062] Optionally, the thickness of the AlGaN three-dimensional sub-layer 411 is 50-100 nm, the thickness of the AlGaN capping sub-layer 412 is 50-100 nm, and the thickness of the AlGaN processing sub-layer 413 is 10-30 nm.

[0063] The thickness of each sub-layer in the AlGaN composite layer 41 is respectively within the above ranges, which can ensure the quality of the obtained AlGaN composite layer 41 while not significantly increasing the preparation cost of the ultraviolet light emitting diode.

[0064] Figure 3 This is another flow chart of a method for preparing an ultraviolet light-emitting diode epitaxial wafer with increased hole content provided by the embodiment of the present disclosure. Figure 3 It can be seen that the method for preparing an ultraviolet light-emitting diode epitaxial wafer with increased hole content further includes:

[0065] S201: providing a substrate.

[0066] Alternatively, the substrate may be a sapphire substrate.

[0067] S202: growing a buffer layer on the substrate, where the buffer layer is an AlN layer.

[0068] The AlN layer in step S202 can be obtained by magnetron sputtering.

[0069] Optionally, the sputtering temperature of the AlN layer is 400-700° C., the sputtering power is 3000-5000 W, and the pressure is 1-10 Torr, so as to obtain a buffer layer of good quality.

[0070] Optionally, step S202 further includes: performing in-situ annealing on the buffer layer at a temperature of 1000° C. to 1200° C., a pressure range of 150 Torr to 500 Torr, and a time period of 5 to 10 minutes, which can further improve the crystal quality of the buffer layer.

[0071] S203: growing an undoped AlGaN layer on the buffer layer.

[0072] Optionally, the growth temperature of the undoped AlGaN layer is 1000° C.-1200° C., and the pressure is 50-200 Torr. The obtained undoped AlGaN layer has better quality, which can improve the crystal quality of the final ultraviolet light-emitting diode.

[0073] Optionally, the undoped AlGaN layer is grown to a thickness between 0.1 and 3.0 micrometers, which can improve the crystal quality of the resulting ultraviolet light-emitting diode.

[0074] S204: growing an N-type AlGaN layer on the undoped AlGaN layer.

[0075] Optionally, the n-type layer is a Si-doped N-type AlGaN layer, which is easy to prepare and obtain.

[0076] Optionally, the growth temperature of the N-type AlGaN layer is 1000° C.-1200° C., and the pressure is 50-200 Torr. The quality of the obtained N-type AlGaN layer is better, which can improve the crystal quality of the final ultraviolet light-emitting diode.

[0077] Exemplarily, the thickness of the N-type AlGaN layer is between 1 and 4.0 micrometers, which can improve the crystal quality of the resulting ultraviolet light-emitting diode.

[0078] For example, in the N-type AlGaN layer, the Si doping concentration is 10 18 cm -3 -10 20 cm -3 between.

[0079] S205: growing a multi-quantum well layer on the N-type AlGaN layer.

[0080] Alternatively, the multi-quantum well layer may include a multi-quantum well structure. The multi-quantum well layer includes a plurality of alternately stacked GaN layers and Al x Ga 1-x N layer 0 <x<0.3。

[0081] For example, the growth temperature of the GaN layer is in the range of 850° C. to 950° C., and the pressure is in the range of 100 Torr to 300 Torr; x Ga 1-xThe growth temperature of the N layer is between 900°C and 1000°C, and the growth pressure is between 50 Torr and 200 Torr, which can produce a high-quality multi-quantum well layer.

[0082] Optionally, the well thickness of the GaN layer is about 3 nm, and the barrier thickness is between 8 nm and 20 nm. The resulting multi-quantum well layer has good quality and reasonable cost.

[0083] S206: growing an electron blocking layer on the multi-quantum well layer.

[0084] Alternatively, the electron blocking layer may be p-type Al y Ga 1-y N-layer 0.2 <y<0.5。

[0085] Alternatively, p-type Al y Ga 1-y The growth temperature of the N layer is 900-1050°C and the pressure is 50-200 Torr. The quality of the obtained p-type doped AlGaN layer is better, which can improve the crystal quality of the final ultraviolet light-emitting diode.

[0086] For example, the p-type doped AlGaN layer is grown to a thickness between 15 and 60 nanometers, which can improve the crystal quality of the resulting ultraviolet light-emitting diode.

[0087] S207: growing a P-type AlGaN layer on the electron blocking layer.

[0088] The growth conditions of the P-type AlGaN layer in step S207 can be referred to Figure 1 Step S103 of the preparation method shown in FIG is omitted for brevity.

[0089] S208: growing a p-type contact layer on the p-type AlGaN layer.

[0090] Optionally, the material of the p-type contact layer may be an aluminum gallium nitride material, and the thickness of the p-type contact layer is 10 to 300 nm, which facilitates the growth and realization of the p-type contact layer.

[0091] It should be noted that in the embodiments disclosed herein, a Veeco K 465i or C4 or RB MOCVD (Metal Organic Chemical Vapor Deposition) device is used to achieve the LED growth method. High-purity H2 (hydrogen) or high-purity N2 (nitrogen) or a mixture of high-purity H2 and high-purity N2 is used as the carrier gas, high-purity NH3 is used as the N source, trimethylgallium (TMGa) and triethylgallium (TEGa) are used as the gallium source, trimethylindium (TMIn) is used as the indium source, silane (SiH4) is used as the N-type dopant, trimethylaluminum (TMAl) is used as the aluminum source, and bis(cyclopentadienyl)magnesium (CP2Mg) is used as the P-type dopant.

[0092] Figure 4 This is a schematic diagram of the structure of another ultraviolet light-emitting diode epitaxial wafer with reduced operating voltage provided by the embodiment of the present disclosure, with reference to Figure 4 It can be seen that Figure 4 The UV LED epitaxial wafer shown in the figure can be made of Figure 3 The method for preparing the ultraviolet light emitting diode epitaxial wafer is obtained by referring to Figure 4 It can be seen that the ultraviolet light-emitting diode epitaxial wafer may include a substrate 1 and a buffer layer 5, an undoped AlGaN layer 6, an N-type AlGaN layer 2, an active layer 3, an electron blocking layer 7, a P-type AlGaN layer 4 and a p-type contact layer 8 stacked in sequence on the substrate 1. The P-type AlGaN layer 4 includes a periodically stacked AlGaN composite layer 41, and each AlGaN composite layer 41 includes an AlGaN three-dimensional sublayer 411, an AlGaN capping sublayer 412 and an AlGaN processing sublayer 413 stacked in sequence.

[0093] It should be noted that Figure 4 The structure of the P-type AlGaN layer 4, Figure 2 The structure of the P-type AlGaN layer 4 shown in FIG is the same as that in FIG, so it will not be described again here.

[0094] Exemplarily, the buffer layer 5 is an AlN layer, which can effectively alleviate the lattice mismatch between the substrate 1 and the structure behind the buffer layer 5 .

[0095] Optionally, the thickness of the buffer layer 5 is 15-35 nm, which can effectively alleviate the lattice mismatch without excessively increasing the preparation cost.

[0096] Optionally, the thickness of the undoped AlGaN layer 6 may be 0.1 to 3.0 micrometers.

[0097] The thickness of the undoped AlGaN layer 6 is appropriate, the cost is reasonable and the quality of the ultraviolet light emitting diode can be effectively improved.

[0098] Optionally, the thickness of the N-type AlGaN layer 2 can be between 1.5 and 3.5 micrometers.

[0099] The N-type AlGaN layer 2 can reasonably provide carriers, and the quality of the N-type AlGaN layer 2 itself is also good.

[0100] Exemplarily, the n-type element doped in the N-type AlGaN layer 2 can be the Si element.

[0101] Exemplarily, the active layer 3 can be a multi-quantum well structure. The active layer 3 includes alternately stacked GaN layers 31 and AlxGa1-xN layers 32, where 0 < x < 0.3. The light-emitting efficiency is better.

[0102] The number of layers of the GaN layer 31 and the AlxGa1-xN layer 32 can be the same, and the number of layers can be 4 to 12. The obtained active layer 3 has good quality and reasonable cost.

[0103] Optionally, the thickness of the GaN layer 31 can be about 3 nm, and the thickness of the AlxGa1-xN layer 32 can be between 8 nm and 20 nm. It can effectively capture carriers and emit light.

[0104] Exemplarily, the electron blocking layer 7 can be a P-type Al y Ga 1-y N layer where 0.2 < y < 0.5, and the thickness of the P-type Al y Ga 1-y N layer can be between 15 nm and 60 nm. The effect of blocking electrons is better.

[0105] Optionally, the thickness of the p-type AlGaN layer 4 is 50 - 300 nm. The obtained p-type AlGaN layer 4 has good overall quality.

[0106] It should be noted that Figure 4 This is only one implementation manner of the ultraviolet light-emitting diode epitaxial wafer provided by the embodiments of the present disclosure. In other implementation manners provided by the present disclosure, the ultraviolet light-emitting diode epitaxial wafer can also be other forms of ultraviolet light-emitting diode epitaxial wafers including a reflective layer, and the present disclosure does not limit this.

[0107] Above, it is not any formal limitation to the present disclosure. Although the present disclosure has been disclosed as above through embodiments, it is not intended to limit the present disclosure. Any person skilled in the art can make some changes or modifications to equivalent embodiments by using the disclosed technical content without departing from the technical solution of the present disclosure. However, as long as it does not depart from the technical solution of the present disclosure, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present disclosure still fall within the scope of the technical solution of the present disclosure.

Claims

1. A method for preparing an ultraviolet light-emitting diode epitaxial wafer with increased hole content, characterized in that: The method for preparing an ultraviolet light-emitting diode epitaxial wafer with increased hole content comprises: providing a substrate; sequentially growing an N-type AlGaN layer and an active layer on the substrate; Periodically growing an AlGaN composite layer on the active layer to obtain a P-type AlGaN layer, wherein the AlGaN composite layer includes an AlGaN three-dimensional sublayer, an AlGaN cap sublayer, and an AlGaN treatment sublayer stacked in sequence, and the AlGaN three-dimensional sublayer includes a plurality of AlGaN island structures stacked on the active layer or on the AlGaN composite layer; The growing of the AlGaN composite layer comprises: Introducing ammonia, Ga source, Al source, and Mg source into the reaction chamber to grow the AlGaN three-dimensional sublayer, wherein the flow ratio of the ammonia to the Ga source is 1000-2000, and the flow ratio of the ammonia to the Al source is 500-1000; Introducing ammonia, Ga source, Al source, and Mg source into the reaction chamber to grow the AlGaN capping sublayer, wherein the flow ratio of the ammonia to the Ga source is 100-200, and the flow ratio of the ammonia to the Al source is 50-100; Only ammonia gas is introduced into the reaction chamber to grow the AlGaN treatment sublayer.

2. The method for preparing an ultraviolet light-emitting diode epitaxial wafer with increased hole content according to claim 1, characterized in that: When growing the AlGaN three-dimensional sublayer, ammonia with a flow rate of 100-200 slm, a Ga source with a flow rate of 0.05-0.2 slm, and an Al source with a flow rate of 0.1-0.4 slm are respectively introduced into the reaction chamber.

3. The method for preparing an ultraviolet light-emitting diode epitaxial wafer with increased hole content according to claim 2, wherein: When growing the AlGaN capping sublayer, ammonia with a flow rate of 10-20 slm, a Ga source with a flow rate of 0.05-0.2 slm, and an Al source with a flow rate of 0.1-0.4 slm are respectively introduced into the reaction chamber.

4. The method for preparing an ultraviolet light-emitting diode epitaxial wafer with increased hole content according to any one of claims 1 to 3, characterized in that: The thickness of the AlGaN three-dimensional sublayer is less than or equal to the thickness of the AlGaN capping sublayer, and the thickness of the AlGaN three-dimensional sublayer is greater than the thickness of the AlGaN processing sublayer.

5. The method for preparing an ultraviolet light-emitting diode epitaxial wafer with increased hole content according to any one of claims 1 to 3, characterized in that: The thickness of the AlGaN three-dimensional sublayer is 50-100 nm, the thickness of the AlGaN capping sublayer is 50-100 nm, and the thickness of the AlGaN processing sublayer is 10-30 nm.

6. The method for preparing an ultraviolet light-emitting diode epitaxial wafer with increased hole content according to any one of claims 1 to 3, characterized in that: The growth time of the AlGaN treatment sublayer is 30-50s.

7. The method for preparing an ultraviolet light-emitting diode epitaxial wafer with increased hole content according to any one of claims 1 to 3, characterized in that: The growth temperature and growth pressure of the AlGaN three-dimensional sub-layer are respectively equal to the growth temperature and growth pressure of the AlGaN capping sub-layer.

8. The method for preparing an ultraviolet light-emitting diode epitaxial wafer with increased hole content according to claim 7, characterized in that: The growth temperature and growth pressure of the AlGaN three-dimensional sublayer are 850° C.-1050° C. and 100-200 Torr respectively.

9. The method for preparing an ultraviolet light-emitting diode epitaxial wafer with increased hole content according to any one of claims 1 to 3, characterized in that: The flow rate of the Mg source introduced during the growth of the AlGaN three-dimensional sub-layer is greater than the flow rate of the Mg source introduced during the growth of the AlGaN capping sub-layer.

10. An ultraviolet light-emitting diode epitaxial wafer with increased hole content, characterized in that: The ultraviolet light-emitting diode epitaxial wafer with increased hole content is prepared using the method for preparing an ultraviolet light-emitting diode epitaxial wafer with increased hole content as described in any one of claims 1 to 9. The ultraviolet light-emitting diode epitaxial wafer with increased hole content includes a substrate and an N-type AlGaN layer, an active layer, and a P-type AlGaN layer sequentially stacked on the substrate. The P-type AlGaN layer includes periodically stacked AlGaN composite layers, and each of the AlGaN composite layers includes sequentially stacked AlGaN three-dimensional sublayers, AlGaN capping sublayers, and AlGaN processing sublayers.

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