Nanometer semiconductor composite material and preparation method and application thereof

Abstract

The invention relates to the technical field of semiconductor composite materials, and discloses a nano semiconductor composite material and a preparation method and application thereof, the nano semiconductor composite material comprises a substrate, a transition metal nitride buffer layer and a co-doped aluminum nitride single crystal film; the transition metal nitride buffer layer is deposited on the surface of one side of the substrate, and the co-doped aluminum nitride single crystal film grows on the side, away from the substrate, of the transition metal nitride buffer layer; from the whole scheme of the invention, through the synergistic effect of the component design and the process steps, the nano semiconductor composite material realizes breakthrough in multiple performance dimensions. The transition metal nitride buffer layer is combined with the co-doped structure, so that the problem that the crystallization quality and the electrical property of a traditional AlN-based material are difficult to consider at the same time is solved; through precise regulation and control of substrate pretreatment and each layer growth process, the defect problem caused by interface mismatch is effectively relieved, and the overall stability of the material is improved.

Description

Technical Field

[0001] This invention relates to the field of semiconductor composite materials technology, specifically to a nano-semiconductor composite material, its preparation method, and its application. Background Technology

[0002] The rapid development of deep ultraviolet optoelectronic devices, high-frequency power devices, and other fields has placed increasingly higher demands on the performance of core semiconductor materials. Aluminum nitride (AlN), as a wide-bandgap semiconductor material, possesses excellent thermal stability, chemical stability, and high breakdown electric field strength, showing broad application prospects in deep ultraviolet light emission and high-frequency signal transmission. However, pure AlN material has poor intrinsic conductivity, and its carrier concentration and mobility are insufficient to meet the practical application requirements of devices.

[0003] Currently, the industry often uses doping to modify AlN, but this method has many problems. For example, when doping with a single element, either the activation efficiency of the dopant element is low, making it difficult to effectively increase the carrier concentration, or it will cause severe lattice distortion of the material, affecting the crystal quality and thus deteriorating the balance between optical and electrical properties.

[0004] On the other hand, there is a large lattice mismatch and difference in thermal expansion coefficient between AlN materials and commonly used substrates (such as sapphire and SiC). During the thin film growth process, a large number of defects (such as dislocations and cracks) are easily generated, which not only reduces the crystal integrity of the material, but also significantly affects the carrier transport efficiency, resulting in a decrease in device reliability.

[0005] Therefore, developing a nanocomposite material for semiconductors that can synergistically optimize crystal quality, electrical properties, and optical properties, and alleviate the interfacial mismatch between the substrate and the thin film, as well as its preparation method, has become a pressing technical challenge for the industry. Summary of the Invention

[0006] To address the problems in the prior art, the present invention provides a nano-semiconductor composite material.

[0007] The technical solution adopted by the present invention to solve its technical problem is: a nano-semiconductor composite material, comprising a substrate, a transition metal nitride buffer layer and a co-doped aluminum nitride single crystal thin film; the transition metal nitride buffer layer is deposited on one side surface of the substrate, and the co-doped aluminum nitride single crystal thin film is grown on the side of the transition metal nitride buffer layer away from the substrate; The co-doped aluminum nitride single crystal thin film is an AlN-Si-M co-doped structure, wherein M is at least one of Ge and Sn. This co-doped structure can suppress the DX transition of Si and improve the conductivity of the thin film. The transition metal nitride buffer layer is at least one of TiN and ZrN. This buffer layer can reduce the lattice mismatch between the substrate and the co-doped aluminum nitride single crystal film and enhance the bonding force. By mass percentage: transition metal nitride buffer layer accounts for 5%-15%, co-doped aluminum nitride single crystal thin film accounts for 85%-95%; In the co-doped aluminum nitride single crystal thin film, the Si doping concentration is 1×10⁻⁶. 18 -5×10 19 cm -3 The doping concentration of M is 5 × 10⁻⁶. 17 -2×10 18 cm -3 The balance is AlN.

[0008] As a further technical solution, the substrate is a sapphire substrate or a SiC substrate; the thickness of the substrate is 200-500μm, and the surface roughness Ra≤1nm.

[0009] As a further technical solution, the thickness of the transition metal nitride buffer layer is 50-200 nm.

[0010] As a further technical solution, the thickness of the co-doped aluminum nitride single crystal film is 1-5 μm.

[0011] A method for producing nano-semiconductor composite materials includes the following steps: S1: Substrate Pretreatment: Select a sapphire or SiC substrate and perform ultrasonic cleaning, plasma etching, and hydroxylation modification sequentially. The ultrasonic cleaning uses a mixed solution of ethanol and deionized water. The plasma etching uses an Ar / O2 mixed gas with a volume ratio of Ar to O2 of 4-6:1, an etching power of 80-120W, and an etching time of 5-15 minutes. The hydroxylation modification involves immersion in a concentrated H2SO4 / H2O2 mixed aqueous solution at a temperature of 60-80℃ for 20-40 minutes. After modification, the substrate is cleaned with deionized water and then dried with nitrogen. The concentrated H2SO4 has a mass fraction of 80%, and the H2O2 has a mass fraction of 10%. S2: Preparation of transition metal nitride buffer layer: A transition metal nitride buffer layer is deposited on the pretreated substrate surface using magnetron sputtering. The sputtering target is a Ti pure target or a Zr pure target, and the sputtering gas is an Ar / N2 mixture with an N2 volume fraction of 20%-40%. The sputtering temperature is 200-300℃, the sputtering power is 150-250W, and the deposition thickness is 50-200nm. Annealing is performed after deposition. S3: Co-doped aluminum nitride single crystal film growth: A substrate with a transition metal nitride buffer layer deposited is placed in an MOCVD reaction chamber. First, a preset step structure with a width of 20-50 nm is constructed on the surface of the buffer layer by plasma etching. Then, aluminum source, nitrogen source, silicon source and germanium / tin source are introduced for low-temperature epitaxial growth. The aluminum source is trimethylaluminum, the nitrogen source is ammonia, the silicon source is silane, the germanium source is germane, and the tin source is tetramethyltin. The growth temperature is 900-1000℃, the growth pressure is 50-100 Torr, the aluminum source flow rate is 50-150 sccm, the nitrogen source flow rate is 500-1500 sccm, the silicon source flow rate is 10-50 sccm, the germanium / tin source flow rate is 5-20 sccm, and the growth time is 1-4 h to obtain a co-doped aluminum nitride single crystal film with a thickness of 1-5 μm. S4: Post-processing optimization: The sample with co-doped aluminum nitride single crystal thin film was subjected to plasma-assisted annealing at a temperature of 500-600℃, a holding time of 20-40min, a plasma power of 50-100W, and an annealing atmosphere of N2 / H2 mixed gas, in which the volume fraction of N2 was 70%-90%, to obtain a nano-semiconductor composite material. As a further technical solution, in step S1, the volume ratio of the mixed solution of ethanol and deionized water is 1:2, the ultrasonic power is 100-150W, the ultrasonic time is 15-25min, and nitrogen gas is used to dry the solution after ultrasonication.

[0012] As a further technical solution, in step S2, after the deposition is completed, an annealing treatment is performed at a temperature of 400-500℃ and a holding time of 30-60 minutes. The annealing atmosphere is nitrogen or argon.

[0013] As a further technical solution, in step S3, the plasma etching parameters are as follows: the etching gas is an Ar / O2 mixture, wherein the volume ratio of Ar to O2 is 3-5:1, the etching power is 50-80W, and the etching time is 2-5min.

[0014] As a further technical solution, in step S4, the N2 / H2 mixed gas flow rate is 200-300 sccm, and radio frequency plasma with a frequency of 13.56 MHz is used.

[0015] Applications of the nano-semiconductor composite material in deep ultraviolet light-emitting diodes, deep ultraviolet detectors, or high-frequency power devices.

[0016] The beneficial effects of this invention are: The introduction of a transition metal nitride buffer layer in this invention provides a good match between its lattice constant and the substrate and the co-doped aluminum nitride single-crystal thin film. This buffer layer effectively alleviates lattice mismatch and differences in thermal expansion coefficients between the substrate and the thin film. Microscopically, the buffer layer lowers the nucleation energy barrier in the early stages of film growth, reduces internal stress caused by lattice distortion, and thus suppresses the formation of defects such as dislocations and cracks. This provides a flat and stable substrate for the growth of the co-doped aluminum nitride single-crystal thin film, thereby ensuring the crystal integrity of the film. The co-doped aluminum nitride single-crystal thin film adopts an AlN-Si-M composite doping structure. Si has high doping activation efficiency, effectively increasing carrier concentration; while the introduction of Ge or Sn can regulate the band structure of AlN, reducing the effective mass of carriers. The synergistic effect of these two elements ensures sufficient carrier supply and improves carrier mobility, thus optimizing electrical performance. Meanwhile, the perturbations of the AlN lattice caused by the composite doping cancel each other out, avoiding the problem of excessive lattice distortion caused by single doping, and taking into account the stability of crystal quality.

[0017] During substrate pretreatment, ultrasonic cleaning uses a mixed solution of ethanol and deionized water, which efficiently removes oil and impurities from the substrate surface, laying a clean foundation for subsequent processing. Plasma etching further cleans surface contaminants and forms a micro-rough structure through physical bombardment and chemical reaction of Ar / O2 mixed gas, enhancing the adhesion between the buffer layer and the substrate. Hydroxylation modification introduces a large number of hydroxyl groups onto the substrate surface through the oxidation effect of a concentrated H2SO4 / H2O2 mixed aqueous solution, improving surface activity and promoting uniform deposition of the buffer layer. This series of pretreatment steps, progressing step by step, optimizes the substrate surface state from three dimensions: cleanliness, surface structure, and activity, providing favorable preconditions for the growth of subsequent layers.

[0018] During the fabrication process, each process step and component design formed a close synergistic effect. In the magnetron sputtering preparation of the transition metal nitride buffer layer, the thickness and crystal quality of the buffer layer could be controlled by adjusting parameters such as the volume fraction of N2 in the sputtering gas, sputtering temperature, and power, ensuring a good interfacial bond with the subsequently grown co-doped aluminum nitride single-crystal film. The annealing treatment after buffer layer deposition further eliminated the internal stress generated during sputtering, improving the structural stability of the buffer layer and providing a better interfacial environment for film growth. Before MOCVD growth of the co-doped aluminum nitride single-crystal film, a pre-defined step structure was constructed through plasma etching, which optimized the nucleation site distribution, promoted the directional growth of the single-crystal film, and improved crystallinity consistency. Precise control of the flow rate of each source gas, growth temperature, and pressure during growth not only ensured the accuracy of the Si and M doping concentrations but also achieved precise control of the film thickness. The post-processing plasma-assisted annealing, under a N2 / H2 mixed atmosphere, further repaired the minor defects generated during film growth, activated some incompletely activated dopants, and improved carrier mobility, thus ultimately optimizing the electrical and optical properties of the material.

[0019] From the overall perspective of this invention, the synergistic effect of component design and process steps enables breakthroughs in multiple performance dimensions of the nano-semiconductor composite material. The combination of the transition metal nitride buffer layer and the co-doped structure solves the problem of balancing crystallinity and electrical performance in traditional AlN-based materials. Precise control of substrate pretreatment and layer growth processes effectively alleviates defects caused by interface mismatch and improves the overall stability of the material. The final composite material exhibits both high crystallinity, ensuring excellent optical performance (such as high transmittance in the deep ultraviolet band), and high carrier concentration and mobility, meeting the electrical performance requirements of devices and achieving synergistic optimization of multiple performance aspects.

[0020] Instruction manual illustrations Figure 1 This is a comparison diagram of the elongation after fracture of an example and a comparative example of a nano-semiconductor composite material. Detailed Implementation

[0021] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] This invention provides a nano-semiconductor composite material, its preparation method, and its application. The nano-semiconductor composite material includes a substrate, a transition metal nitride buffer layer, and a co-doped aluminum nitride single crystal film. The transition metal nitride buffer layer is deposited on one side of the substrate, and the co-doped aluminum nitride single crystal film is grown on the side of the transition metal nitride buffer layer away from the substrate.

[0023] In this invention, the substrate is a sapphire substrate or a SiC substrate, and any commercially available product well known to those skilled in the art can be used; the thickness of the substrate is preferably 200-500 μm, and the surface roughness Ra≤1 nm.

[0024] In this invention, the transition metal nitride buffer layer is at least one of TiN and ZrN, and its thickness is preferably 50-200 nm; the transition metal nitride buffer layer accounts for 5%-15% of the mass percentage of the nano-semiconductor composite material.

[0025] In this invention, the co-doped aluminum nitride single crystal film is an AlN-Si-M co-doped structure, wherein M is at least one of Ge and Sn; the mass percentage of the co-doped aluminum nitride single crystal film in the nano-semiconductor composite material is preferably 85%-95%; the thickness of the co-doped aluminum nitride single crystal film is preferably 1-5 μm; and the doping concentration of Si is preferably 1×10⁻⁶. 18 cm -3 -5×10 19 cm -3 The preferred doping concentration of M is 5 × 10⁻⁶. 17 cm -3 -2×10 18 cm -3 The balance is AlN.

[0026] This invention also provides a method for preparing the above-mentioned nano-semiconductor composite material, comprising the following steps: S1: Substrate Pretreatment: Select a sapphire or SiC substrate and perform ultrasonic cleaning, plasma etching, and hydroxylation modification sequentially. The ultrasonic cleaning uses a mixed solution of ethanol and deionized water, with a preferred volume ratio of ethanol to deionized water of 1:2. The preferred ultrasonic power is 100-150W, and the preferred ultrasonic time is 15-25 min. After ultrasonic cleaning, the substrate is dried with nitrogen. The plasma etching uses an Ar / O2 mixed gas, with a preferred volume ratio of Ar to O2 of 4-6:1. The preferred etching power is 80-120W, and the preferred etching time is 5-15 min. The hydroxylation modification involves immersion in a concentrated H2SO4 / H2O2 mixed aqueous solution, with a concentrated H2SO4 mass fraction of 80% and an H2O2 mass fraction of 10%. The preferred immersion temperature is 60℃-80℃, and the preferred immersion time is 20-40 min. After modification, the substrate is cleaned with deionized water and then dried with nitrogen for later use.

[0027] S2: Preparation of Transition Metal Nitride Buffer Layer: A transition metal nitride buffer layer is deposited on the pretreated substrate surface using magnetron sputtering. The sputtering target is a pure Ti target or a pure Zr target, and the sputtering gas is an Ar / N2 mixture, wherein the N2 volume fraction is preferably 20-40%, the sputtering temperature is preferably 200-300℃, the sputtering power is preferably 150-250W, and the deposition thickness is 50-200nm. After deposition, annealing is performed, with the annealing temperature preferably 400-500℃, the holding time preferably 30-60min, and the annealing atmosphere being nitrogen or argon.

[0028] S3: Co-doped aluminum nitride single crystal thin film growth: The substrate with a transition metal nitride buffer layer deposited is placed in the MOCVD reaction chamber. A preset step structure is first constructed on the surface of the buffer layer by plasma etching. The step width is preferably 20-50nm. The plasma etching parameters are: the etching gas is an Ar / O2 mixed gas, wherein the volume ratio of Ar to O2 is preferably 3-5:1, the etching power is preferably 50-80W, and the etching time is preferably 2-5min. Low-temperature epitaxial growth is then performed by introducing aluminum, nitrogen, silicon, and germanium / tin sources. The aluminum source is trimethylaluminum, the nitrogen source is ammonia, the silicon source is silane, the germanium source is germane, and the tin source is tetramethyltin. The preferred growth temperature is 900-1000℃, the preferred growth pressure is 50-100 Torr, the preferred aluminum source flow rate is 50-150 sccm, the preferred nitrogen source flow rate is 500-1500 sccm, the preferred silicon source flow rate is 10-50 sccm, the preferred germanium / tin source flow rate is 5-20 sccm, and the preferred growth time is 1-4 h, resulting in a co-doped aluminum nitride single crystal film with a thickness of 1-5 μm.

[0029] S4: Post-processing optimization: The sample with co-doped aluminum nitride single crystal thin film is subjected to plasma-assisted annealing. The annealing temperature is preferably 500-600℃, the holding time is preferably 20-40min, the plasma power is preferably 50-100W, the annealing atmosphere is N2 / H2 mixed gas, wherein the N2 volume fraction is preferably 70-90%, the N2 / H2 mixed gas flow rate is preferably 200-300sccm, and radio frequency plasma with a frequency of 13.56MHz is used to finally obtain nano-semiconductor composite material.

[0030] The nano-semiconductor composite material provided by this invention effectively alleviates the lattice mismatch and thermal expansion coefficient difference between the substrate and the co-doped aluminum nitride single-crystal thin film by introducing a transition metal nitride buffer layer, thereby improving the crystallinity quality of the thin film. The AlN-Si-M co-doped structure synergistically regulates the electrical and optical properties of the material, broadening its application scenarios. Furthermore, the preparation method of this invention offers controllable process parameters, good repeatability, and stable preparation of high-performance nano-semiconductor composite materials, which can be widely used in deep ultraviolet light-emitting diodes, deep ultraviolet detectors, or high-frequency power devices.

[0031] To further illustrate the present invention, detailed descriptions are provided below through examples, comparative examples, and experiments.

[0032] Example 1: S1: Substrate Pretreatment: A sapphire substrate with a thickness of 200 μm and a surface roughness Ra of 0.8 nm was selected. A mixed solution of ethanol and deionized water in a volume ratio of 1:2 was prepared. The substrate was immersed in the mixed solution for ultrasonic cleaning at a power of 100 W for 15 min, followed by drying with nitrogen. Subsequently, plasma etching was performed using an Ar / O2 mixed gas with a volume ratio of Ar to O2 of 4:1, an etching power of 80 W, and an etching time of 5 min. Next, hydroxylation modification was performed by immersion in a concentrated H2SO4 / H2O2 mixed aqueous solution (80% H2SO4, 10% H2O2) at a temperature of 60 °C for 20 min. After modification, the substrate was cleaned with deionized water and then dried with nitrogen for later use.

[0033] S2: Preparation of the transition metal nitride buffer layer: A TiN buffer layer was deposited on the pretreated substrate surface using magnetron sputtering. The sputtering target was a pure Ti target, and the sputtering gas was an Ar / N2 mixture with an N2 volume fraction of 20%. The sputtering temperature was 200℃, the sputtering power was 150W, and the deposition thickness was 50nm. After deposition, annealing was performed at 400℃ for 30 minutes in a nitrogen atmosphere. At this point, the TiN buffer layer accounted for 5% of the mass percentage of the nano-semiconductor composite material.

[0034] S3: Growth of Co-doped Aluminum Nitride Single Crystal Thin Film: A substrate with a deposited TiN buffer layer was placed in an MOCVD reaction chamber. A pre-defined step structure with a step width of 20 nm was first constructed on the surface of the buffer layer by plasma etching. The plasma etching parameters were: an Ar / O2 mixed gas with an Ar to O2 volume ratio of 3:1, an etching power of 50 W, and an etching time of 2 min. Then, trimethylaluminum, ammonia, silane, and germane were introduced for low-temperature epitaxial growth. The growth temperature was 900℃, the growth pressure was 50 Torr, the aluminum source flow rate was 50 sccm, the nitrogen source flow rate was 500 sccm, the silicon source flow rate was 10 sccm, the germanium source flow rate was 5 sccm, and the growth time was 1 h, resulting in a 1 μm thick AlN-Si-Ge co-doped single crystal thin film. This co-doped aluminum nitride single crystal thin film accounted for 95% of the mass of the nano-semiconductor composite material, with a Si doping concentration of 1 × 10⁻⁶. 18 cm -3 The doping concentration of Ge is 5 × 10⁻⁶. 17 cm -3 The balance is AlN.

[0035] S4: Post-processing optimization: The sample with co-doped aluminum nitride single crystal thin film was subjected to plasma-assisted annealing at a temperature of 500℃, a holding time of 20min, a plasma power of 50W, and an annealing atmosphere of N2 / H2 mixed gas with a volume fraction of 70% N2 and a flow rate of 200sccm. Radio frequency plasma with a frequency of 13.56MHz was used to obtain the nano-semiconductor composite material.

[0036] Example 2: S1: Substrate Pretreatment: A SiC substrate with a thickness of 350 μm and a surface roughness Ra of 0.5 nm was selected. A mixed solution of ethanol and deionized water in a volume ratio of 1:2 was prepared. The substrate was immersed in the mixed solution for ultrasonic cleaning at a power of 125 W for 20 min, followed by drying with nitrogen. Subsequently, plasma etching was performed using an Ar / O2 mixed gas with a volume ratio of Ar to O2 of 5:1, at a power of 100 W for 10 min. Next, hydroxylation modification was performed by immersion in a concentrated H2SO4 / H2O2 mixed aqueous solution (80% H2SO4, 10% H2O2) at 70 °C for 30 min. After modification, the substrate was rinsed with deionized water and then dried with nitrogen for later use.

[0037] S2: Preparation of the transition metal nitride buffer layer: A ZrN buffer layer was deposited on the pretreated substrate surface using magnetron sputtering. A pure Zr target was used as the sputtering target, and an Ar / N2 mixture was used as the sputtering gas, with N2 comprising 30% by volume. The sputtering temperature was 250℃, the sputtering power was 200W, and the deposition thickness was 125nm. After deposition, annealing was performed at 450℃ for 45 minutes in an argon atmosphere. At this point, the ZrN buffer layer accounted for 10% of the mass percentage of the nano-semiconductor composite material.

[0038] S3: Growth of Co-doped Aluminum Nitride Single Crystal Thin Film: A substrate with a deposited ZrN buffer layer was placed in an MOCVD reaction chamber. A pre-defined step structure with a step width of 35 nm was first constructed on the surface of the buffer layer by plasma etching. The plasma etching parameters were: an Ar / O2 mixed gas with an Ar to O2 volume ratio of 4:1, an etching power of 65 W, and an etching time of 3.5 min. Then, trimethylaluminum, ammonia, silane, and tetramethyltin were introduced for low-temperature epitaxial growth. The growth temperature was 950℃, the growth pressure was 75 Torr, the aluminum source flow rate was 100 sccm, the nitrogen source flow rate was 1000 sccm, the silicon source flow rate was 30 sccm, the tin source flow rate was 12.5 sccm, and the growth time was 2.5 h, resulting in a 3 μm thick AlN-Si-Sn co-doped single crystal thin film. This co-doped aluminum nitride single crystal thin film accounted for 90% of the mass of the nano-semiconductor composite material, with a Si doping concentration of 3 × 10⁻⁶. 19 cm -3 The Sn doping concentration is 1.25 × 10⁻⁶. 18 cm -3 The balance is AlN.

[0039] S4: Post-processing optimization: The sample with co-doped aluminum nitride single crystal thin film was subjected to plasma-assisted annealing at a temperature of 550℃, a holding time of 30 min, a plasma power of 75W, and an annealing atmosphere of N2 / H2 mixed gas with a volume fraction of 80% N2 and a flow rate of 250 sccm. Radio frequency plasma with a frequency of 13.56MHz was used to obtain the nano-semiconductor composite material.

[0040] Example 3: S1: Substrate Pretreatment: A sapphire substrate with a thickness of 500 μm and a surface roughness Ra of 0.3 nm was selected. A mixed solution of ethanol and deionized water in a volume ratio of 1:2 was prepared. The substrate was immersed in the mixed solution for ultrasonic cleaning at a power of 150 W for 25 min, followed by drying with nitrogen. Subsequently, plasma etching was performed using an Ar / O2 mixed gas with a volume ratio of Ar to O2 of 6:1, at a power of 120 W for 15 min. Next, hydroxylation modification was performed by immersion in a concentrated H2SO4 / H2O2 mixed aqueous solution (80% H2SO4, 10% H2O2) at 80°C for 40 min. After modification, the substrate was rinsed with deionized water and then dried with nitrogen for later use.

[0041] S2: Preparation of the transition metal nitride buffer layer: A TiN buffer layer was deposited on the pretreated substrate surface using magnetron sputtering. The sputtering target was a pure Ti target, and the sputtering gas was an Ar / N2 mixture with an N2 volume fraction of 40%. The sputtering temperature was 300℃, the sputtering power was 250W, and the deposition thickness was 200nm. After deposition, annealing was performed at 500℃ for 60 minutes in a nitrogen atmosphere. At this point, the TiN buffer layer accounted for 15% of the mass percentage of the nano-semiconductor composite material.

[0042] S3: Growth of Co-doped Aluminum Nitride Single Crystal Thin Film: A substrate with a deposited TiN buffer layer was placed in an MOCVD reaction chamber. A pre-defined step structure with a step width of 50 nm was first constructed on the surface of the buffer layer by plasma etching. The plasma etching parameters were: an Ar / O2 mixed gas with a volume ratio of Ar to O2 of 5:1, an etching power of 80 W, and an etching time of 5 min. Then, trimethylaluminum, ammonia, silane, and germane were introduced for low-temperature epitaxial growth. The growth temperature was 1000℃, the growth pressure was 100 Torr, the aluminum source flow rate was 150 sccm, the nitrogen source flow rate was 1500 sccm, the silicon source flow rate was 50 sccm, the germanium source flow rate was 20 sccm, and the growth time was 4 h, resulting in a 5 μm thick AlN-Si-Ge co-doped single crystal thin film. This co-doped aluminum nitride single crystal thin film accounted for 85% of the mass of the nano-semiconductor composite material, with a Si doping concentration of 5 × 10⁻⁶. 19 cm -3 The doping concentration of Ge is 2 × 10⁻⁶. 18 cm -3 The balance is AlN.

[0043] S4: Post-processing optimization: The sample with co-doped aluminum nitride single crystal thin film was subjected to plasma-assisted annealing at a temperature of 600℃, a holding time of 40min, a plasma power of 100W, and an annealing atmosphere of N2 / H2 mixed gas with a volume fraction of 90% N2 and a flow rate of 300sccm. Radio frequency plasma with a frequency of 13.56MHz was used to obtain the nano-semiconductor composite material.

[0044] Comparative Example 1: The preparation method of Example 2 is adopted, except that: no transition metal nitride buffer layer is set, and co-doped aluminum nitride single crystal thin film is directly grown on the surface of the pretreated SiC substrate.

[0045] Comparative Example 2: The preparation method of Example 2 is adopted, except that the co-doped aluminum nitride single crystal film is a single Si-doped AlN-Si structure without adding M (Sn) doping source.

[0046] Comparative Example 3 The preparation method of Example 2 is adopted, except that the co-doped aluminum nitride single crystal film is an AlN-M single doping structure (only Sn doping) without adding Si doping source.

[0047] Comparative Example 4 The preparation method of Example 2 is adopted, except that: in step S3, plasma etching is not performed to construct the preset step structure, and co-doped aluminum nitride single crystal thin film is directly grown on the surface of the transition metal nitride buffer layer.

[0048] Experiment 1: Crystallization quality test; The crystallinity of the nano-semiconductor composite materials prepared in Examples 1-3 and Comparative Examples 1-4 was tested using X-ray diffraction (XRD). The test conditions were: CuKα radiation, wavelength λ = 0.15406 nm, scanning range 2θ = 20°-80°, scanning speed 5° / min, and step size 0.02°. The full width at half maximum (FWHM) of the diffraction peaks of the (002) crystal plane was obtained by testing. A smaller FWHM indicates better crystallinity. Simultaneously, the crystallinity was calculated; higher crystallinity indicates superior crystallinity. The experimental data are as follows: Table 1

[0049] The experimental data show that the full width at half maximum (FWHM) of the (002) crystal plane diffraction peaks in Examples 1-3 are all less than 0.25°, and the crystallinity is all higher than 92%, indicating excellent crystal quality. In contrast, the FWHMs of Comparative Examples 1-4 are all greater than 0.35°, and the crystallinity is all lower than 87%, indicating significantly poorer crystal quality.

[0050] Comparative Example 1 lacked a transition metal nitride buffer layer, resulting in significant lattice mismatch and a large difference in thermal expansion coefficients between the substrate and the co-doped aluminum nitride single-crystal film. This led to numerous defects during film growth, increased half-width at half-maximum (FWHM) of diffraction peaks, and a significant decrease in crystallinity. Comparative Examples 2 and 3 employed single-Si and single-Sn doping, respectively. The lack of synergistic effect between the two doping elements prevented effective control of lattice arrangement, resulting in lower crystallinity compared to the examples. Comparative Example 4 did not utilize plasma etching to construct the pre-defined stepped structure, leading to insufficient surface smoothness of the buffer layer and uneven distribution of nucleation sites during film growth. This resulted in decreased crystallinity, increased FWHM, and reduced crystallinity.

[0051] Experiment 2: Electrical Performance Test The electrical properties of the nano-semiconductor composite materials prepared in Examples 1-3 and Comparative Examples 1-4 were tested using a Hall effect analyzer. The test temperature was room temperature (25℃), and the test magnetic field strength was 0.5T. Test parameters included carrier concentration, mobility, and resistivity. Higher carrier concentration and mobility, and lower resistivity indicated superior electrical performance. The experimental data are as follows: Table 2

[0052] The experimental data show that the carrier concentrations in Examples 1-3 are all higher than 1.2 × 10⁻⁶. 18 cm -3 The mobility rates were all higher than 380 cm. 2 ・V -1 ・s -1 The resistivity is below 2.1 × 10⁻⁶. -3 The Ω·cm concentration indicates excellent electrical performance. In contrast, the carrier concentrations of Comparative Examples 1-4 are generally low, with mobilities less than 300 cm⁻¹. 2 ・V -1 ・s -1 The resistivity is higher than 3.2×10⁻⁶. -3 Ω・cm, indicating significantly poor electrical performance.

[0053] Comparative Example 1, lacking a transition metal nitride buffer layer, exhibits numerous thin film crystal defects. These defects act as carrier scattering centers, leading to a significant decrease in carrier mobility and an increase in resistivity. Simultaneously, these defects also affect the activation efficiency of the dopant elements, resulting in a low carrier concentration. Comparative Example 2, with single Si doping, exhibits a larger effective carrier mass, limiting mobility. Comparative Example 3, with single Sn doping, has a higher activation energy, making it difficult to increase carrier concentration; therefore, the electrical performance of both is inferior to the AlN-Si-M co-doped structure in the examples. Comparative Example 4, lacking a pre-defined stepped structure, suffers from uneven dopant element distribution during thin film growth, obstructing carrier transport paths, resulting in decreased mobility and increased resistivity.

[0054] Experiment 3: Optical performance test The optical properties of the nano-semiconductor composite materials prepared in Examples 1-3 and Comparative Examples 1-4 were tested using a UV-Vis spectrophotometer in the deep ultraviolet (DUV) band. The test parameter was the DUV transmittance; higher transmittance indicates better optical performance and suitability for DUV-related devices. The experimental data are as follows: Table 3

[0055] The experimental data show that Examples 1-3 all exhibit transmittance exceeding 82% in the deep ultraviolet band (250nm-350nm), with transmittance exceeding 91% at 350nm, demonstrating excellent optical performance that meets the application requirements of deep ultraviolet devices. Comparative Examples 1-4, on the other hand, show transmittance below 74% in the same band, with the highest transmittance at 350nm at only 84.3%, indicating poor optical performance.

[0056] Comparative Example 1 lacked a transition metal nitride buffer layer, resulting in significant internal defects and stress in the film. These defects caused strong scattering and absorption of deep ultraviolet light, leading to a significant decrease in transmittance. Comparative Examples 2 and 3 employed a single doping method, which could not effectively control the band structure of the material, resulting in strong absorption of deep ultraviolet light and thus lower transmittance than the examples. Comparative Example 4 did not construct a predetermined stepped structure, resulting in a large surface roughness of the film and uneven distribution of internal dopants, which increased the probability of light scattering and reduced transmittance.

[0057] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A nano-semiconductor composite material, characterized in that, It includes a substrate, a transition metal nitride buffer layer, and a co-doped aluminum nitride single crystal film; the transition metal nitride buffer layer is deposited on one side surface of the substrate, and the co-doped aluminum nitride single crystal film is grown on the side of the transition metal nitride buffer layer away from the substrate; The co-doped aluminum nitride single crystal thin film has an AlN-Si-M co-doped structure, wherein M is at least one of Ge and Sn; The transition metal nitride buffer layer is at least one of TiN and ZrN; By mass percentage: transition metal nitride buffer layer accounts for 5%-15%, co-doped aluminum nitride single crystal thin film accounts for 85%-95%; In the co-doped aluminum nitride single crystal thin film, the Si doping concentration is 1×10⁻⁶. 18 -5×10 19 cm -3 The doping concentration of M is 5 × 10⁻⁶. 17 -2×10 18 cm -3 The balance is AlN.

2. The nano-semiconductor composite material according to claim 1, characterized in that, The substrate is a sapphire substrate or a SiC substrate; the thickness of the substrate is 200-500 μm, and the surface roughness Ra≤1 nm.

3. The nano-semiconductor composite material according to claim 1, characterized in that, The thickness of the transition metal nitride buffer layer is 50-200 nm.

4. The nano-semiconductor composite material according to claim 1, characterized in that, The thickness of the co-doped aluminum nitride single crystal film is 1-5 μm.

5. A method for preparing the nano-semiconductor composite material according to any one of claims 1-4, characterized in that, Includes the following steps: S1: Substrate Pretreatment: Select a sapphire or SiC substrate and perform ultrasonic cleaning, plasma etching, and hydroxylation modification sequentially. The ultrasonic cleaning uses a mixed solution of ethanol and deionized water. The plasma etching uses an Ar / O2 mixed gas with a volume ratio of Ar to O2 of 4-6:1, an etching power of 80-120W, and an etching time of 5-15 minutes. The hydroxylation modification involves immersion in a concentrated H2SO4 / H2O2 mixed aqueous solution at a temperature of 60-80℃ for 20-40 minutes. After modification, the substrate is cleaned with deionized water and then dried with nitrogen. The concentrated H2SO4 has a mass fraction of 80%, and the H2O2 has a mass fraction of 10%. S2: Preparation of transition metal nitride buffer layer: A transition metal nitride buffer layer is deposited on the pretreated substrate surface using magnetron sputtering. The sputtering target is a Ti pure target or a Zr pure target, and the sputtering gas is an Ar / N2 mixture with an N2 volume fraction of 20%-40%. The sputtering temperature is 200-300℃, the sputtering power is 150-250W, and the deposition thickness is 50-200nm. Annealing is performed after deposition. S3: Co-doped aluminum nitride single crystal film growth: A substrate with a transition metal nitride buffer layer deposited is placed in an MOCVD reaction chamber. First, a preset step structure with a width of 20-50 nm is constructed on the surface of the buffer layer by plasma etching. Then, aluminum source, nitrogen source, silicon source and germanium / tin source are introduced for low-temperature epitaxial growth. The aluminum source is trimethylaluminum, the nitrogen source is ammonia, the silicon source is silane, the germanium source is germane, and the tin source is tetramethyltin. The growth temperature is 900-1000℃, the growth pressure is 50-100 Torr, the aluminum source flow rate is 50-150 sccm, the nitrogen source flow rate is 500-1500 sccm, the silicon source flow rate is 10-50 sccm, the germanium / tin source flow rate is 5-20 sccm, and the growth time is 1-4 h to obtain a co-doped aluminum nitride single crystal film with a thickness of 1-5 μm. S4: Post-processing optimization: The sample with co-doped aluminum nitride single crystal thin film was subjected to plasma-assisted annealing at a temperature of 500-600℃, a holding time of 20-40 min, a plasma power of 50-100W, and an annealing atmosphere of N2 / H2 mixed gas, in which the volume fraction of N2 was 70%-90%, to obtain a nano-semiconductor composite material.

6. The preparation method according to claim 5, characterized in that, In step S1, the volume ratio of the mixed solution of ethanol and deionized water is 1:2, the ultrasonic power is 100-150W, the ultrasonic time is 15-25min, and nitrogen gas is used to dry the solution after ultrasonication.

7. The preparation method according to claim 5, characterized in that, In step S2, after deposition, annealing is performed at a temperature of 400-500℃ for 30-60 minutes in a nitrogen or argon atmosphere.

8. The preparation method according to claim 5, characterized in that, In step S3, the plasma etching parameters are as follows: the etching gas is an Ar / O2 mixture, wherein the volume ratio of Ar to O2 is 3-5:1, the etching power is 50-80W, and the etching time is 2-5min.

9. The preparation method according to claim 5, characterized in that, In step S4, the N2 / H2 mixed gas flow rate is 200-300 sccm, and radio frequency plasma with a frequency of 13.56 MHz is used.

10. The application of the nano-semiconductor composite material according to any one of claims 1-4 in deep ultraviolet light-emitting diodes, deep ultraviolet detectors, or high-frequency power devices.

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