Dual-wavelength LED epitaxial structure and preparation method thereof and dual-wavelength LED device

Abstract

The present invention relates to the field of semiconductor device technology, and specifically to a dual-wavelength LED epitaxial structure, a preparation method thereof, and a dual-wavelength LED device. The dual-wavelength LED epitaxial structure includes a substrate layer, an N-type semiconductor layer, a channel defect initiation layer, a channel defect expansion layer, a multi-quantum well light-emitting layer, and a P-type semiconductor layer; the N-type semiconductor layer is located on the upper surface of the substrate layer; the channel defect initiation layer is located on the upper surface of the N-type semiconductor layer; the channel defect expansion layer is located on the upper surface of the channel defect initiation layer to amplify the channel defect; at least one channel defect is a ring structure, and the multi-quantum well light-emitting layer includes a first light-emitting area located on the outer circle of the ring structure, having a first wavelength, and a second light-emitting area located on the inner circle of the ring structure, having a second wavelength, and the second wavelength is greater than the first wavelength. The LED epitaxial structure of the present invention can realize dual-wavelength light emission, and the wavelength light emission ratio will not change significantly with the change of current, and the color temperature is stable.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor devices, and in particular to a dual-wavelength LED epitaxial structure and a preparation method thereof, and a dual-wavelength LED device. Background Art

[0002] Light-emitting diodes (LEDs) can efficiently convert electrical energy into light energy, and emit light by releasing energy through the recombination of electrons and holes. They are widely used in lighting, display and other fields. With the development of technology, the demand for full spectrum in white light illumination has increased. Integrating multiple wavelengths on the same chip can effectively reduce the manufacturing cost of full spectrum devices. In addition, in the production process of Micro LED, mass transfer technology is one of the main technical bottlenecks in its development. Integrating multiple wavelengths on the same chip can reduce the technical pressure of mass transfer and reduce the difficulty of manufacturing Micro LED products. The existing dual-wavelength LED technology grows quantum wells of two wavelengths in the active area one after another, and emits two wavelengths at the same time after current injection. Under this technology, the ratio of the two wavelengths of light emission will change with the current. The reason is that as the current density changes from small to large, the carrier distribution position will change. Because of the existence of V-pits, the carrier distribution is close to the N-type GaN side at a small current density, and the carrier distribution is close to the P-type GaN side at a large current density. Therefore, the color temperature is inconsistent under different currents.

[0003] In view of this, the present invention is proposed. Summary of the invention

[0004] One object of the present invention is to provide a dual-wavelength LED epitaxial structure to solve the problem of inconsistent color temperature under different current densities in the dual-wavelength LED structure in the prior art; the dual-wavelength LED epitaxial structure of the present invention can realize dual-wavelength light emission, so that the color temperature of the LED device under different current densities is stable.

[0005] Another object of the present invention is to provide a method for preparing a dual-wavelength LED epitaxial structure, which is simple and easy to implement.

[0006] Another object of the present invention is to provide a dual-wavelength LED device.

[0007] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are particularly adopted:

[0008] A dual-wavelength LED epitaxial structure comprises a substrate layer, an N-type semiconductor layer, a channel defect initiation layer, a channel defect expansion layer, a multi-quantum well light-emitting layer and a P-type semiconductor layer; the N-type semiconductor layer is located on the upper surface of the substrate layer; the channel defect initiation layer is located on the upper surface of the N-type semiconductor layer away from the substrate layer; the channel defect expansion layer is located on the upper surface of the channel defect initiation layer away from the substrate layer, for amplifying the channel defect; at least one channel defect is a ring structure, and the multi-quantum well light-emitting layer comprises a first light-emitting region located on the outer circle of the ring structure, having a first wavelength, and a second light-emitting region located on the inner circle of the ring structure, having a second wavelength, and the second wavelength is greater than the first wavelength.

[0009] In one embodiment, the carbon content in the channel defect initiation layer is not less than 5×10 17 atoms / cm 3 .

[0010] In one embodiment, the channel defect initiation layer is further doped with elemental silicon, and the content of the elemental silicon is not lower than the carbon content in the channel defect initiation layer.

[0011] In one embodiment, the thickness of the channel defect initiation layer is 10 nm to 200 nm.

[0012] In one embodiment, the inner ring and outer ring of the annular structure have a height difference; the vertical distance between the upper surface of the inner ring of the annular structure and the upper surface of the substrate is smaller than the vertical distance between the upper surface of the outer ring and the upper surface of the substrate.

[0013] In one embodiment, the difference between the first wavelength and the second wavelength is not less than 10 nm.

[0014] In one embodiment, a ratio A of the carbon content in the channel defect initiation layer to the carbon content in the N-type semiconductor layer satisfies: A≥2.

[0015] In one embodiment, a ratio B of the carbon content in the channel defect initiation layer to the carbon content in the channel defect expansion layer satisfies: B≥2.

[0016] In one embodiment, the multi-quantum well light-emitting layer includes an InGaN layer and a GaN layer stacked together.

[0017] In one embodiment, the thickness of the multi-quantum well light-emitting layer is 100 nm to 300 nm.

[0018] In one embodiment, a buffer material layer is further disposed between the substrate layer and the N-type semiconductor layer.

[0019] In one embodiment, the buffer material layer is made of AlGaN, and the thickness of the buffer material layer is 10-30 nm.

[0020] In one embodiment, the N-type semiconductor layer includes a Si-doped N-type GaN layer and an undoped GaN layer, wherein the Si-doped N-type GaN layer is away from the substrate layer, and the Si doping concentration in the Si-doped N-type GaN layer is 2.5×10 19 atoms / cm 3 ~6×10 19 atoms / cm 3 .

[0021] In one embodiment, the thickness of the N-type semiconductor layer is 3.5 μm to 10 μm.

[0022] In one embodiment, the P-type semiconductor layer includes a stacked electron blocking layer and a Mg-doped P-type GaN layer, the electron blocking layer is made of an AlGaN layer, and the Mg-doped P-type GaN layer has a Mg doping concentration of 0.8×10 20 ~2×10 20 atoms / cm 3 .

[0023] In one embodiment, the thickness of the P-type semiconductor layer is 190nm~300nm.

[0024] The method for preparing the dual-wavelength LED epitaxial structure as described above comprises the following steps:

[0025] An N-type semiconductor layer is prepared on one side of the substrate layer; a channel defect initiation layer is prepared on the surface of the N-type semiconductor layer; a channel defect expansion layer is prepared on the surface of the channel defect initiation layer to amplify the channel defect; a multi-quantum well light-emitting layer is prepared on the channel defect expansion layer; and a P-type semiconductor layer is prepared on the surface of the multi-quantum well light-emitting layer.

[0026] In one embodiment, the preparation conditions of the channel defect initiation layer include: using TMGa as the Ga source, the preparation atmosphere is nitrogen, the preparation pressure is 180mbar~230mbar, and the preparation temperature is 720℃~780℃ to obtain a GaN layer.

[0027] In one embodiment, the preparation conditions of the channel defect expansion layer include: alternately preparing InGaN layers and GaN layers in sequence, with a preparation pressure of 180 mbar to 230 mbar and a preparation temperature of 870° C. to 960° C.

[0028] In one embodiment, the preparation conditions of the multi-quantum well light-emitting layer include: using TEGa as the Ga source, alternately preparing InGaN layers and GaN layers in sequence, the preparation temperature of GaN is 850~930℃, and the preparation temperature of InGaN is 740℃~830℃.

[0029] In one embodiment, the method further includes: before preparing the N-type semiconductor layer, preparing a buffer material layer on the surface of the substrate layer.

[0030] In one embodiment, the preparation conditions of the buffer material layer include: preparing the AlGaN layer at a temperature of 500°C to 600°C, and then annealing the AlGaN layer under ammonia conditions at a temperature of 1100°C to 1200°C.

[0031] In one embodiment, the preparation conditions of the N-type semiconductor layer include: first preparing a GaN layer, and then preparing a Si-doped N-type GaN layer, the preparation pressure is 550 mbar~650 mbar, and the preparation temperature is 1120°C~1180°C.

[0032] In one embodiment, the preparation conditions of the P-type semiconductor layer include: sequentially preparing an electron blocking layer and a Mg-doped P-type GaN layer, the preparation pressure is 180 mbar~220 mbar, and the preparation temperature is 970°C~1080°C.

[0033] A dual-wavelength LED device comprises the dual-wavelength LED epitaxial structure, a P-electrode layer and an N-electrode layer, wherein the P-electrode layer is electrically connected to the P-type semiconductor layer; and the N-electrode is electrically connected to the N-type semiconductor layer.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] (1) The dual-wavelength LED epitaxial structure of the present invention, the channel defect generating layer and the amplifying layer can realize dual-wavelength light emission in the active layer, the wavelength light emission ratio will not change significantly with the change of current, and the color temperature is stable.

[0036] (2) The preparation method of the dual-wavelength LED epitaxial structure of the present invention is simple and easy. The preparation scheme of the channel defect starting layer and the channel defect expansion layer is clear and simple. The P-type covering layer is used to repair the channel defect to restore the surface to a smooth state. The luminous wavelength of the internal area surrounded by the channel defect is significantly longer than that of the outside of the channel defect, thereby realizing dual-wavelength luminescence, and the luminous ratio will not change significantly with the change of current, and the color temperature is stable. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the specific implementation mode of the present invention or the technical solution in the prior art, the drawings required for use in the specific implementation mode or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are one implementation mode of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0038] Figure 1 It is a structural schematic diagram of the dual-wavelength LED epitaxial structure of the present invention;

[0039] Figure 2 It is a schematic diagram of the structure of the dual-wavelength LED device in the present invention;

[0040] Figure 3 is a top view of the channel defect of the present invention;

[0041] Figure 4 It is a side view of the channel defect of the present invention.

[0042] Reference numerals:

[0043] 1-substrate layer, 2-buffer material layer, 3-N-type semiconductor layer, 4-channel defect starting layer, 5-channel defect expansion layer, 6-multi-quantum well light-emitting layer, 7-P-type semiconductor layer, 8-current blocking layer, 9-current expansion layer, 10-P electrode layer, 11-N electrode layer, 12-insulating material layer, 13-first light-emitting area, 14-second light-emitting area, 15-annular channel defect. DETAILED DESCRIPTION

[0044] The embodiments of the present invention will be described in detail below in conjunction with the examples, but it will be appreciated by those skilled in the art that the following examples are only used to illustrate the present invention and should not be considered as limiting the scope of the present invention. If no specific conditions are specified in the examples, the conditions are carried out according to normal conditions or the conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be obtained commercially.

[0045] The present invention provides a dual-wavelength LED epitaxial structure, comprising a substrate layer, an N-type semiconductor layer, a channel defect initiation layer, a channel defect expansion layer, a multi-quantum well light-emitting layer and a P-type semiconductor layer. The N-type semiconductor layer is located on the upper surface of the substrate layer; the channel defect initiation layer is located on the upper surface of the N-type semiconductor layer away from the substrate layer; the channel defect expansion layer is located on the upper surface of the channel defect initiation layer away from the substrate layer, for amplifying the channel defect; at least one channel defect is a ring structure, and the multi-quantum well light-emitting layer comprises a first light-emitting region located on the outer circle of the ring structure, having a first wavelength, and a second light-emitting region located on the inner circle of the ring structure, having a second wavelength, and the second wavelength is greater than the first wavelength.

[0046] The dual-wavelength LED epitaxial structure of the present invention utilizes the characteristics of stress relaxation inside the channel defect and increased effective incorporation of the element In through the coordination of the channel defect starting layer, the channel defect expansion layer and the multi-quantum well light-emitting layer. The light-emitting wavelength of the internal area surrounded by the channel defect is significantly longer than that of the area outside the channel defect, thereby realizing dual-wavelength light emission, the wavelength light emission ratio will not change significantly with the change of current, and the color temperature is stable.

[0047] In the present invention, the first wavelength is the normal wavelength of the multi-quantum well active region, which is controlled by the amount of In incorporated set by the program; the second wavelength is the wavelength generated by the internal region surrounded by the channel defect due to stress relaxation and the increase in the amount of In incorporated; it is controlled by the "amount of In incorporated set by the program" and the "degree of stress relaxation of the channel defect". The first wavelength ranges from 430nm to 460nm, and the second wavelength ranges from 460nm to 550nm.

[0048] In the present invention, the channel defect initiation layer and the channel defect expansion layer can realize dual-wavelength luminescence in the quantum well active layer. In this structure, the MQWs emitting two wavelengths are not grown successively, but are in parallel positions. The change in carrier distribution position caused by the change in current density will not affect the luminescence ratio. The wavelength luminescence ratio will not change significantly with the change in current, and the color temperature is stable.

[0049] In one embodiment, the carbon content in the channel defect initiation layer is not less than 5×10 17 atoms / cm 3 , for example 5.1×10 17 atoms / cm 3 , 5.2×10 17 atoms / cm 3 , 5.4×10 17 atoms / cm 3 , 5.5×10 17 atoms / cm 3 , 5.8×10 17 atoms / cm 3 , 6×10 17 atoms / cm 3 , 6.5×10 17 atoms / cm 3 ,7×10 17 atoms / cm 3 , 7.5×10 17 atoms / cm 3 wait.

[0050] In one embodiment, the channel defect initiation layer is further doped with elemental silicon, and the content of the elemental silicon is not less than the carbon content in the channel defect initiation layer. In one embodiment, the content of the elemental silicon is 5.3×10 17 atoms / cm 3 , 5.4×10 17 atoms / cm 3 , 5.6×10 17 atoms / cm 3 , 5.9×10 17 atoms / cm 3 , 6×10 17 atoms / cm 3 , 6.4×10 17 atoms / cm 3 ,7×10 17 atoms / cm 3 , 7.8×10 17 atoms / cm 3 wait.

[0051] In one embodiment, the thickness of the channel defect initiation layer is 10nm to 200nm. In one embodiment, the thickness of the channel defect initiation layer includes but is not limited to 10nm, 20nm, 50nm, 80nm, 100nm, 120nm, 150nm, 180nm, 200nm, etc., or any range value between the two. The channel defect initiation layer of the present invention has a suitable thickness to ensure the dual-wavelength luminescence effect. If the thickness of the channel defect initiation layer is too thick, the quality of the device will deteriorate. If the thickness of the channel defect initiation layer is too thin, the substrate stacking fault is too little, which is not conducive to the dual-wavelength luminescence effect.

[0052] In one embodiment, a ratio A of the carbon content in the channel defect initiation layer to the carbon content in the N-type semiconductor layer satisfies: A≥2, for example, 2, 3, 4, 5, 6, etc.

[0053] In one embodiment, the ratio B of the carbon content in the channel defect initiation layer to the carbon content in the channel defect expansion layer satisfies: B≥2, such as 2, 3, 4, 5, 6, etc.

[0054] The present invention is more conducive to ensuring the performance of LED devices by limiting the ratio of the carbon content in the channel defect initiation layer to the carbon content in the N-type semiconductor layer to A≥2 and the ratio of the carbon content in the channel defect initiation layer to the carbon content in the channel defect expansion layer to B≥2.

[0055] In one embodiment, the inner ring and outer ring of the annular structure have a height difference; the vertical distance between the upper surface of the inner ring of the annular structure and the upper surface of the substrate is smaller than the vertical distance between the upper surface of the outer ring and the upper surface of the substrate.

[0056] In one embodiment, the difference between the first wavelength and the second wavelength is not less than 10 nm, for example, 15 nm, 20 nm, 25 nm, 30 nm, 35 nm, 40 nm, 50 nm, etc.

[0057] In one embodiment, the multi-quantum well light-emitting layer includes an InGaN layer and a GaN layer stacked. The thickness of the multi-quantum well light-emitting layer is 100nm~300nm, for example, it can be but not limited to 110nm, 120nm, 150nm, 180nm, 200nm, 250nm, 300nm, etc., or any range value between the two. The multi-quantum well light-emitting layer of suitable thickness and material of the present invention is conducive to the preparation of the subsequent channel defect starting layer to ensure the dual-wavelength light-emitting effect. In some embodiments, the multi-quantum well light-emitting layer includes a stack formed by multiple pairs of InGaN layers and GaN layers, such as 2~15 pairs, such as 2 pairs, 3 pairs, 5 pairs, 10 pairs, 12 pairs or 15 pairs.

[0058] In one embodiment, a buffer material layer is further provided between the substrate layer and the N-type semiconductor layer. The material of the buffer material layer includes AlGaN, and the thickness of the buffer material layer is 10-30 nm, for example, but not limited to 10 nm, 15, 20, 25, 30 nm, etc., or any range value between the two. The buffer material layer of suitable thickness of the present invention can ensure the optical performance of the LED epitaxial structure and improve the device quality.

[0059] In one embodiment, the N-type semiconductor layer includes a Si-doped N-type GaN layer and an undoped GaN layer, wherein the Si-doped N-type GaN layer is away from the substrate layer, and the Si doping concentration in the Si-doped N-type GaN layer is 2.5×10 19 ~6×10 19 atoms / cm 3 , for example 2.5×10 19 atoms / cm 3 , 3×10 19 atoms / cm 3 , 4×10 19 atoms / cm 3 , 5×10 19 atoms / cm 3 , 6×10 19 atoms / cm 3The thickness of the N-type semiconductor layer is 3.5 μm to 10 μm, such as 4 μm, 5 μm, 6 μm, 7 μm, 9 μm or 10 μm, etc. The N-type semiconductor layer of the present invention can increase the current expansion capability and improve the crystal quality of the LED epitaxial structure.

[0060] In one embodiment, the thickness of the non-doped GaN layer is 2-5 μm, and the thickness of the Si-doped N-type GaN layer is 2-5 μm.

[0061] In one embodiment, the P-type semiconductor layer includes a stacked electron blocking layer and a Mg-doped P-type GaN layer, the electron blocking layer is made of an AlGaN layer, and the Mg-doped P-type GaN layer has a Mg doping concentration of 0.8×10 20 ~2×10 20 atoms / cm 3 , for example 0.8×10 20 atoms、1×10 20 atoms、1.3×10 20 atoms、1.8×10 20 atoms、2×10 20 atoms, etc. In one embodiment, the thickness of the P-type semiconductor layer is 190nm to 300nm, such as 190nm, 200nm, 210nm, 220nm, 230nm, 240nm, 300nm, etc. The P-type semiconductor layer of the present invention with a suitable thickness can ensure the crystal quality of the epitaxial structure and the flatness of the surface of the epitaxial structure.

[0062] The present invention also provides a method for preparing the dual-wavelength LED epitaxial structure as described above, comprising the following steps:

[0063] An N-type semiconductor layer is prepared on one surface of the substrate layer; a channel defect initiation layer is prepared on the surface of the N-type semiconductor layer; a channel defect expansion layer is prepared on the surface of the channel defect initiation layer to amplify the channel defect; a multi-quantum well light-emitting layer is prepared on the channel defect expansion layer; and a P-type semiconductor layer is prepared on the surface of the multi-quantum well light-emitting layer.

[0064] The preparation method of the dual-wavelength LED epitaxial structure of the present invention is simple and easy. The preparation scheme of the channel defect starting layer and the channel defect expansion layer is clear and simple. The P-type covering layer is used to repair the channel defect to restore the surface to be flat. The luminous wavelength of the internal area surrounded by the channel defect is significantly longer than that of the outside of the channel defect, thereby realizing dual-wavelength luminescence.

[0065] In one embodiment, before preparing the N-type semiconductor layer, a buffer material layer is prepared on the surface of the substrate layer; the preparation conditions of the buffer material layer include: a preparation temperature of 500°C to 600°C, for example, 500°C, 520°C, 530°C, 550°C, 570°C, 600°C, etc., to obtain an AlGaN layer, and then annealing is performed under ammonia (NH3) conditions to allow the low-temperature AlGaN to recrystallize into island-shaped seed crystals, and the annealing temperature is 1100°C to 1200°C, for example, 1100°C, 1110°C, 1140°C, 1150°C, 1160°C or 1200°C, etc.

[0066] In one embodiment, the preparation conditions of the N-type semiconductor layer include: introducing TMGa and growing a 0.8-1.2 μm thick three-dimensional layer at a pressure of 750-820 mbar. The temperature is raised to 1120°C-1180°C (e.g., 1120°C, 1130°C, 1150°C, 1180°C, etc.), and the pressure is reduced to 550 mbar-650 mbar (e.g., 550 mbar, 580 mbar, 600 mbar or 650 mbar, etc.) to prepare a GaN layer; and then a Si-doped N-type GaN layer is prepared on the surface of the GaN layer, and the Si doping concentration is 2.5×10 19 ~6×10 19 atoms / cm 3 The preparation temperature is 1120℃~1180℃, and the preparation pressure is 550mbar~650mbar.

[0067] In one embodiment, the preparation conditions of the channel defect initiation layer include: using TMGa as a Ga source, a nitrogen atmosphere, a preparation temperature of 720°C to 780°C, such as 720°C, 730°C, 750°C, 760°C or 780°C, etc., and a preparation pressure of 180mbar to 230mbar, such as 180mbar, 200mbar, 230mbar, etc., to obtain a GaN layer. The present invention adopts appropriate preparation conditions for the channel defect initiation layer to obtain a large number of substrate stacking fault structures, and can make the carbon content of the channel defect generation layer not less than 5×10 17atoms / cm 3 . This lays a good foundation for the subsequent preparation of dual wavelengths with stable color temperature.

[0068] In one embodiment, the preparation conditions of the channel defect expansion layer include: alternately preparing InGaN layers and GaN layers in sequence, the preparation temperature is 870°C to 960°C, such as 870°C, 880°C, 900°C, 920°C, 960°C, etc., and the preparation pressure is 180mbar to 230mbar, such as 180mbar, 200mbar, 210mbar, 230mbar, etc. The preparation of the channel defect expansion layer of the present invention adopts appropriate conditions, and uses lattice mismatch stress to trigger the substrate stacking fault to form a channel defect and amplify it, which is conducive to the subsequent realization of dual-wavelength luminescence, and the luminescence ratio will not change significantly with the change of current, and the color temperature is stable.

[0069] In one embodiment, the preparation conditions of the multi-quantum well light-emitting layer include: using TEGa as the Ga source, alternately preparing InGaN layers and GaN layers in sequence, the preparation temperature of GaN is 850°C to 930°C, for example, 850°C, 860°C, 900°C, 930°C, etc., and the preparation temperature of InGaN is 740°C to 830°C, for example, 740°C, 760°C, 800°C, 830°C, etc.

[0070] In one embodiment, the preparation conditions of the P-type semiconductor layer include: sequentially preparing an electron blocking layer (AlGaN layer) and a Mg-doped P-type GaN layer, the preparation temperature is 970°C to 1080°C, for example, 970°C, 1000°C, 1050°C, 1080°C, etc., and the preparation pressure is 180mbar to 220mbar, for example, 180mbar, 200mbar, 220mbar, etc.

[0071] The present invention also provides a dual-wavelength LED device, comprising the dual-wavelength LED epitaxial structure, and a P electrode layer and an N electrode layer, wherein the P electrode layer is electrically connected to the P-type semiconductor layer; and the N electrode is electrically connected to the N-type semiconductor layer.

[0072] Specifically, the dual-wavelength LED device of the present invention includes the above-mentioned dual-wavelength LED epitaxial structure, as well as a current spreading layer, a current blocking layer, a P-electrode layer, an N-electrode layer and an insulating material layer; the current blocking layer is located on the surface of the P-type semiconductor layer of the dual-wavelength LED epitaxial structure; the current spreading layer covers the P-type semiconductor layer and is located on the surface of the P-type semiconductor layer; the P-electrode layer is located on the current spreading layer and is electrically connected to the P-type semiconductor layer; the N-electrode layer is located in the N-step region and is electrically connected to the N-type semiconductor layer; the insulating material layer covers the N-electrode layer and the P-electrode layer, and exposes portions of the N-electrode layer and the P-electrode layer.

[0073] The light emitting diode of the invention has high quality and excellent light effect.

[0074] The following is further explained in conjunction with specific embodiments.

[0075] Example 1

[0076] A dual-wavelength LED epitaxial structure, such as Figure 1 As shown, it includes a substrate layer 1, a buffer material layer 2, an N-type semiconductor layer 3, a channel defect initiation layer 4, a channel defect expansion layer 5, a multi-quantum well light-emitting layer 6 and a P-type semiconductor layer 7.

[0077] The buffer material layer 2 is located on the surface of the substrate layer 1, and the thickness of the buffer material layer 2 is 25 nm. The N-type semiconductor layer 3 is located on the surface of the buffer material layer 2, and the N-type semiconductor layer 3 includes a Si-doped N-type GaN layer and an undoped GaN layer, and the thicknesses are 2 μm, respectively. The Si-doped N-type GaN layer is far away from the substrate layer 1, and the Si doping concentration in the Si-doped N-type GaN layer is 3×10 19 atoms / cm 3 The channel defect initiation layer 4 is located on the surface of the N-type semiconductor layer 3 away from the substrate layer 1, and the carbon content in the channel defect initiation layer 4 is 6×10 17 atoms / cm 3 , with a thickness of 60nm. The channel defect initiation layer is also doped with elemental silicon, with an elemental silicon content of 8×10 17 atoms / cm 3 , elemental silicon is derived from silane; the ratio of the carbon content in the channel defect initiation layer 4 to the carbon content in the N-type semiconductor layer 3 is A=4; the ratio of the carbon content in the channel defect initiation layer 4 to the carbon content in the channel defect expansion layer 5 is B=4. The channel defect expansion layer 5 is located on the surface of the channel defect initiation layer 4 away from the substrate layer 1 to amplify the channel defect; at least one channel defect is a ring structure, and the top view of the channel defect is as shown in Figure 3 As shown, the side view is Figure 4 As shown, the multi-quantum well light-emitting layer includes a first light-emitting region 13 located in the outer circle of the annular channel defect 15, having a first wavelength, and a second light-emitting region 14 located in the inner circle of the annular channel defect 15, having a second wavelength, and the second wavelength is greater than the first wavelength; wherein the first wavelength is 450nm and the second wavelength is 510nm. The multi-quantum well light-emitting layer 6 includes 10 pairs of InGaN layers and GaN layers stacked, the thickness of the InGaN layer is 2nm, and the thickness of the GaN layer is 10nm. The P-type semiconductor layer 7 is located on the flat layer structure surface of the multi-quantum well light-emitting layer 6, and the P-type semiconductor layer 7 includes a stacked electron blocking layer and a Mg-doped P-type GaN layer, the material of the electron blocking layer includes an AlGaN layer, and the Mg-doped P-type GaN layer has a Mg doping concentration of 1×10 20 atoms / cm 3 .

[0078] The method for preparing the dual-wavelength LED epitaxial structure in this embodiment includes the following steps:

[0079] (a) A 20 nm thick AlGaN buffer material layer 2 is grown on the surface of a sapphire substrate layer 1 at 550°C. Annealing is performed in an NH3 atmosphere and the temperature is raised to 1110°C to allow the low-temperature AlGaN to recrystallize into island-shaped seed crystals.

[0080] (b) TMGa is introduced and a three-dimensional layer with a thickness of 1 μm is grown at a pressure of 800 mbar.

[0081] (c) The temperature is raised to 1150°C and the pressure is reduced to 600 mbar, and a non-doped GaN layer with a thickness of 2 μm is grown; at a temperature of 1150°C and a pressure of 600 mbar, a Si-doped N-type GaN layer with a thickness of 2 μm is grown on the surface of the non-doped GaN layer to obtain an N-type semiconductor layer 3.

[0082] (d) The temperature is lowered to 750°C, and TMGa is used as the Ga source. Under the pressure condition of 200 mbar and pure N2 atmosphere, a channel defect initiation layer 4 (GaN layer) is grown.

[0083] (e) The temperature is raised to 880° C. and the pressure is 200 mbar, and three pairs of InGaN layers and GaN layers are grown to obtain a channel defect expansion layer 5.

[0084] (f) Ten pairs of InGaN layers and GaN layers are grown on the channel surface of the channel defect expansion layer 5. The gallium source is TEGa. The thickness of the InGaN layer is 2 nm, the thickness of the GaN layer is 10 nm, the growth temperature of the InGaN layer is 870°C, and the growth temperature of the GaN layer is 790°C, to obtain a multi-quantum well light-emitting layer 6.

[0085] (g) The temperature is raised to 1000° C. and a P-type AlGaN electron blocking layer is grown under a pressure of 200 mbar. The aluminum source is turned off and a Mg-doped P-type GaN layer is continued to be grown at the same temperature and pressure to obtain a P-type semiconductor layer 7.

[0086] Example 2

[0087] A dual-wavelength LED epitaxial structure comprises a substrate layer 1, a buffer material layer 2, an N-type semiconductor layer 3, a channel defect initiation layer 4, a channel defect expansion layer 5, a multi-quantum well light-emitting layer 6 and a P-type semiconductor layer 7.

[0088] The buffer material layer 2 is located on the surface of the substrate layer 1, and the thickness of the buffer material layer 2 is 15 nm. The N-type semiconductor layer 3 is located on the surface of the buffer material layer 2, and the N-type semiconductor layer 3 includes a Si-doped N-type GaN layer and an undoped GaN layer, and the thicknesses are 3 μm respectively. The Si-doped N-type GaN layer is far away from the substrate layer 1, and the Si doping concentration in the Si-doped N-type GaN layer is 4×10 19 atoms / cm 3 The channel defect initiation layer 4 is located on the surface of the N-type semiconductor layer 3 away from the substrate layer 1, and the carbon content in the channel defect initiation layer 4 is 7×10 17 atoms / cm 3 , with a thickness of 40nm. The channel defect initiation layer is also doped with elemental silicon, with an elemental silicon content of 9×10 17 atoms / cm 3 , elemental silicon is derived from silane; the ratio of the carbon content in the channel defect initiation layer 4 to the carbon content in the N-type semiconductor layer 3 is A=2; the ratio of the carbon content in the channel defect initiation layer 4 to the carbon content in the channel defect expansion layer 5 is B=2. The channel defect expansion layer 5 is located on the surface of the channel defect initiation layer 4 away from the substrate layer 1, and is used to amplify the channel defect; at least one channel defect is a ring structure, and the multi-quantum well light-emitting layer includes a first light-emitting area 13 located on the outer circle of the ring channel defect 15, having a first wavelength, and a second light-emitting area 14 located on the inner circle of the ring channel defect 15, having a second wavelength; the second wavelength is greater than the first wavelength; wherein the first wavelength is 450nm and the second wavelength is 465nm. The multi-quantum well light-emitting layer 6 includes 10 pairs of InGaN layers and GaN layers stacked, the thickness of the InGaN layer is 2.5nm, and the thickness of the GaN layer is 10nm. The P-type semiconductor layer 7 is located on the flat layer structure surface of the multi-quantum well light-emitting layer 6. The P-type semiconductor layer 7 includes a stacked electron blocking layer and a Mg-doped P-type GaN layer. The material of the electron blocking layer includes an AlGaN layer. In the Mg-doped P-type GaN layer, the Mg doping concentration is 1.5×10 20 atoms / cm 3 .

[0089] The method for preparing the dual-wavelength LED epitaxial structure in this embodiment includes the following steps:

[0090] (a) An AlGaN buffer material layer 2 is grown on the surface of a sapphire substrate layer 1 at 600°C. Annealing is performed in an NH3 atmosphere and the temperature is raised to 1180°C to allow the low-temperature AlGaN to recrystallize into island-shaped seed crystals.

[0091] (b) TMGa is introduced and a three-dimensional layer with a thickness of 1.2 μm is grown at a pressure of 780 mbar.

[0092] (c) The temperature is raised to 1180°C and the pressure is reduced to 650 mbar to grow an undoped GaN layer; at a temperature of 1180°C and a pressure of 650 mbar, a Si-doped N-type GaN layer is grown on the surface of the undoped GaN layer to obtain an N-type semiconductor layer 3.

[0093] (d) The temperature is lowered to 780°C, and TMGa is used as the Ga source. Under the pressure condition of 200 mbar and pure N2 atmosphere, a channel defect initiation layer 4 (GaN layer) is grown.

[0094] (e) The temperature is raised to 900° C. and the pressure is 220 mbar, and three pairs of InGaN layers and GaN layers are grown to obtain a channel defect expansion layer 5.

[0095] (f) Ten pairs of InGaN layers and GaN layers are grown on the channel surface of the channel defect expansion layer 5. The gallium source is TEGa. The growth temperature of the InGaN layer is 930°C and the growth temperature of the GaN layer is 830°C, thereby obtaining a multi-quantum well light-emitting layer 6.

[0096] (g) The temperature is raised to 1080° C. and a P-type AlGaN electron blocking layer is grown under a pressure of 220 mbar. The aluminum source is turned off and a Mg-doped P-type GaN layer is continued to be grown at the same temperature and pressure to obtain a P-type semiconductor layer 7.

[0097] Example 3

[0098] A dual-wavelength LED epitaxial structure comprises a substrate layer 1, a buffer material layer 2, an N-type semiconductor layer 3, a channel defect initiation layer 4, a channel defect expansion layer 5, a multi-quantum well light-emitting layer 6 and a P-type semiconductor layer 7.

[0099] The buffer material layer 2 is located on the surface of the substrate layer 1, and the thickness of the buffer material layer 2 is 10 nm. The N-type semiconductor layer 3 is located on the surface of the buffer material layer 2, and the N-type semiconductor layer 3 includes a Si-doped N-type GaN layer and an undoped GaN layer, and the thicknesses are 3.5 μm, respectively. The Si-doped N-type GaN layer is far away from the substrate layer 1, and the Si doping concentration in the Si-doped N-type GaN layer is 7.5×10 19 atoms / cm 3 The channel defect initiation layer 4 is located on the surface of the N-type semiconductor layer 3 away from the substrate layer 1, and the carbon content in the channel defect initiation layer 4 is 5.5×10 17 atoms / cm 3 , with a thickness of 100 nm. The channel defect initiation layer is also doped with elemental silicon, with an elemental silicon content of 6×10 17 atoms / cm 3, elemental silicon is derived from silane; the ratio of the carbon content in the channel defect initiation layer 4 to the carbon content in the N-type semiconductor layer 3 is A=3; the ratio of the carbon content in the channel defect initiation layer 4 to the carbon content in the channel defect expansion layer 5 is B=3. The channel defect expansion layer 5 is located on the surface of the channel defect initiation layer 4 away from the substrate layer 1, and is used to amplify the channel defect; at least one channel defect is a ring structure, and the multi-quantum well light-emitting layer includes a first light-emitting area 13 located on the outer circle of the ring channel defect 15, having a first wavelength, and a second light-emitting area 14 located on the inner circle of the ring channel defect 15, having a second wavelength, and the second wavelength is greater than the first wavelength; wherein the first wavelength is 450nm and the second wavelength is 540nm. The multi-quantum well light-emitting layer 6 includes 10 pairs of InGaN layers and GaN layers stacked, the thickness of the InGaN layer is 3.5nm, and the thickness of the GaN layer is 10nm. The P-type semiconductor layer 7 is located on the flat layer structure surface of the multi-quantum well light-emitting layer 6. The P-type semiconductor layer 7 includes a stacked electron blocking layer and a Mg-doped P-type GaN layer. The material of the electron blocking layer includes an AlGaN layer. In the Mg-doped P-type GaN layer, the Mg doping concentration is 1.8×10 20 atoms / cm 3 .

[0100] The method for preparing the dual-wavelength LED epitaxial structure in this embodiment includes the following steps:

[0101] (a) An AlGaN buffer material layer 2 is grown on the surface of a sapphire substrate layer 1 at 500°C. Annealing is performed in an NH3 atmosphere and the temperature is raised to 1100°C to allow the low-temperature AlGaN to recrystallize into island-shaped seed crystals.

[0102] (b) TMGa is introduced and a three-dimensional layer with a thickness of 0.8 μm is grown at a pressure of 800 mbar.

[0103] (c) The temperature is raised to 1150°C and the pressure is reduced to 600 mbar to grow an undoped GaN layer; at a temperature of 1120°C and a pressure of 550 mbar, a Si-doped N-type GaN layer is grown on the surface of the undoped GaN layer to obtain an N-type semiconductor layer 3.

[0104] (d) The temperature is lowered to 720°C, and TMGa is used as the Ga source. Under the pressure condition of 180 mbar and pure N2 atmosphere, a channel defect initiation layer 4 (GaN layer) is grown.

[0105] (e) The temperature is raised to 870° C. and the pressure is 180 mbar, and three pairs of InGaN layers and GaN layers are grown to obtain a channel defect expansion layer 5.

[0106] (f) Ten pairs of InGaN layers and GaN layers are grown on the channel surface of the channel defect expansion layer 5. The gallium source is TEGa. The thickness of the InGaN layer is 2 nm, the thickness of the GaN layer is 10 nm, the growth temperature of the InGaN layer is 850°C, and the growth temperature of the GaN layer is 740°C, to obtain a multi-quantum well light-emitting layer 6.

[0107] (g) The temperature is raised to 970° C. and a P-type AlGaN electron blocking layer is grown under a pressure of 180 mbar. The aluminum source is turned off and a Mg-doped P-type GaN layer is continued to be grown at the same temperature and pressure to obtain a P-type semiconductor layer 7.

[0108] Example 4

[0109] A dual-wavelength LED epitaxial structure, which differs from Embodiment 1 in that:

[0110] The carbon content in the channel defect initiation layer 4 is 5×10 17 atoms / cm 3 , the thickness is 40nm, the ratio of the carbon content in the channel defect initiation layer 4 to the carbon content in the N-type semiconductor layer 3 is A=3; the ratio of the carbon content in the channel defect initiation layer 4 to the carbon content in the channel defect expansion layer 5 is B=2.

[0111] Example 5

[0112] A dual-wavelength LED epitaxial structure, which differs from Embodiment 1 in that:

[0113] The carbon content in the channel defect initiation layer 4 is 7.5×10 17 atoms / cm 3 , the thickness is 100 nm, the ratio of the carbon content in the channel defect initiation layer 4 to the carbon content in the N-type semiconductor layer 3 is A=6; the ratio of the carbon content in the channel defect initiation layer 4 to the carbon content in the channel defect expansion layer 5 is B=6.

[0114] Example 6

[0115] A dual wavelength LED device, such as Figure 2As shown, it includes a dual-wavelength LED epitaxial structure, as well as a current spreading layer 9, a current blocking layer 8, a P-electrode layer 10, an electrode and an insulating material layer 12; the current blocking layer 8 is located on the surface of the P-type semiconductor layer 7 of the dual-wavelength LED epitaxial structure; the current spreading layer 9 covers the P-type semiconductor layer 7 and is located on the surface of the P-type semiconductor layer 7; the P-electrode layer 10 is located on the current spreading layer 9 and is electrically connected to the P-type semiconductor layer 7; the N-electrode layer 11 is located in the N-step region and is electrically connected to the N-type semiconductor layer 3; the insulating material layer 12 covers the N-electrode layer 11 and the P-electrode layer 10, and exposes part of the N-electrode layer 11 and the P-electrode layer 10.

[0116] The dual-wavelength LED epitaxial structure in this embodiment adopts the dual-wavelength LED epitaxial structure in Embodiments 1 to 5 respectively.

[0117] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. However, these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A dual-wavelength LED epitaxial structure, characterized in that: It includes a substrate layer, an N-type semiconductor layer, a channel defect initiation layer, a channel defect expansion layer, a multi-quantum well light-emitting layer and a P-type semiconductor layer; The N-type semiconductor layer is located on the upper surface of the substrate layer; the channel defect initiation layer is located on the upper surface of the N-type semiconductor layer away from the substrate layer, the channel defect initiation layer includes GaN, and the channel defect initiation layer is also doped with carbon and silicon; the channel defect expansion layer is located on the upper surface of the channel defect initiation layer away from the substrate layer, for amplifying the channel defect, the channel defect expansion layer includes alternating InGaN layers and GaN layers; at least one channel defect is a ring structure, and the multi-quantum well light-emitting layer includes a first light-emitting area located on the outer circle of the ring structure, having a first wavelength, and a second light-emitting area located on the inner circle of the ring structure, having a second wavelength, and the second wavelength is greater than the first wavelength.

2. The dual-wavelength LED epitaxial structure according to claim 1, characterized in that: Contains at least one of the following features (1) to (5): (1) The carbon content in the channel defect initiation layer is not less than 5×10 17 atoms / cm 3 ; (2) The silicon content is not less than the carbon content in the channel defect initiation layer; (3) The thickness of the channel defect initiation layer is 10 nm to 200 nm; (4) The inner ring and the outer ring of the annular structure have a height difference; the vertical distance between the upper surface of the inner ring of the annular structure and the upper surface of the substrate is smaller than the vertical distance between the upper surface of the outer ring and the upper surface of the substrate; (5) The difference between the first wavelength and the second wavelength is not less than 10 nm.

3. The dual-wavelength LED epitaxial structure according to claim 2, characterized in that: A ratio A of the carbon content in the channel defect initiation layer to the carbon content in the N-type semiconductor layer satisfies: A≥2; And / or, a ratio B of the carbon content in the channel defect initiation layer to the carbon content in the channel defect expansion layer satisfies: B≥2.

4. The dual-wavelength LED epitaxial structure according to claim 1, characterized in that: Contains at least one of the following features (1) to (2): (1) The multi-quantum well light-emitting layer includes an InGaN layer and a GaN layer stacked together; (2) The thickness of the multi-quantum well light-emitting layer is 100nm~300nm.

5. The dual-wavelength LED epitaxial structure according to claim 1, characterized in that: Contains at least one of the following features (1) to (6): (1) A buffer material layer is further provided between the substrate layer and the N-type semiconductor layer; (2) A buffer material layer is further provided between the substrate layer and the N-type semiconductor layer, the material of the buffer material layer includes AlGaN, and the thickness of the buffer material layer is 10-30 nm; (3) The N-type semiconductor layer includes a Si-doped N-type GaN layer and an undoped GaN layer. The Si-doped N-type GaN layer is away from the substrate layer. The Si doping concentration in the Si-doped N-type GaN layer is 2.5×10 19 atoms / cm 3 ~6×10 19 atoms / cm 3 ; (4) The thickness of the N-type semiconductor layer is 3.5 μm to 10 μm; (5) The P-type semiconductor layer includes an electron blocking layer and a Mg-doped P-type GaN layer stacked in layers, the electron blocking layer includes an AlGaN layer, and the Mg-doped P-type GaN layer has a Mg doping concentration of 0.8×10 20 ~2×10 20 atoms / cm 3 ; (6) The thickness of the P-type semiconductor layer is 190nm~300nm.

6. A method for preparing a dual-wavelength LED epitaxial structure, characterized in that: The following steps are involved: An N-type semiconductor layer is prepared on one side of the substrate layer; a channel defect initiation layer is prepared on the surface of the N-type semiconductor layer, wherein the channel defect initiation layer includes GaN and is further doped with carbon and silicon; a channel defect expansion layer is prepared on the surface of the channel defect initiation layer to amplify the channel defect, wherein the channel defect expansion layer includes alternating InGaN layers and GaN layers; A multi-quantum well light-emitting layer is prepared on the channel defect expansion layer; and a P-type semiconductor layer is prepared on the surface of the multi-quantum well light-emitting layer.

7. The method for preparing a dual-wavelength LED epitaxial structure according to claim 6, characterized in that: Contains at least one of the following features (1) to (2): (1) The preparation conditions of the channel defect initiation layer include: using TMGa as a Ga source, a nitrogen atmosphere, a pressure of 180 mbar to 230 mbar, and a temperature of 720° C. to 780° C. to obtain a GaN layer; (2) The preparation conditions of the channel defect expansion layer include: alternately preparing InGaN layers and GaN layers in sequence, with a preparation pressure of 180 mbar to 230 mbar and a preparation temperature of 870° C. to 960° C.

8. The method for preparing a dual-wavelength LED epitaxial structure according to claim 6, characterized in that: The preparation conditions of the multi-quantum well light-emitting layer include: using TEGa as a Ga source, alternately preparing InGaN layers and GaN layers in sequence, the preparation temperature of InGaN is 740°C to 830°C, and the preparation temperature of GaN is 850°C to 930°C.

9. The method for preparing a dual-wavelength LED epitaxial structure according to claim 6, characterized in that: Contains at least one of the following features (1) to (3): (1) It also includes: before preparing the N-type semiconductor layer, preparing a buffer material layer on the surface of the substrate layer; the preparation conditions of the buffer material layer include: preparing the AlGaN layer at a temperature of 500°C to 600°C, and then annealing the AlGaN layer under ammonia conditions at a temperature of 1100°C to 1200°C; (2) The preparation conditions of the N-type semiconductor layer include: first preparing a GaN layer, and then preparing a Si-doped N-type GaN layer, the preparation pressure is 550 mbar~650 mbar, and the preparation temperature is 1120°C~1180°C; (3) The preparation conditions of the P-type semiconductor layer include: sequentially preparing an electron blocking layer and a Mg-doped P-type GaN layer, the preparation pressure is 180 mbar~220 mbar, and the preparation temperature is 970°C~1080°C.

10. A dual-wavelength LED device, characterized in that: It comprises the dual-wavelength LED epitaxial structure according to any one of claims 1 to 5, and a P-electrode layer and an N-electrode layer, wherein the P-electrode layer is electrically connected to the P-type semiconductor layer; and the N-electrode is electrically connected to the N-type semiconductor layer.

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