Wide band gap nitride quantum well, preparation method and wide band gap semiconductor device

Abstract

The invention belongs to the technical field of semiconductor material preparation, and provides a wide bandgap nitride quantum well, a preparation method and a wide bandgap semiconductor device.The wide bandgap nitride quantum well comprises a quantum well structure, and the quantum well structure comprises a quantum well layer and a quantum barrier layer growing on the quantum well layer; a nitrogen vacancy at a nitride quantum well heterogeneous interface is introduced at the interface of the quantum well layer and the quantum barrier layer, accurately designed defect states are introduced into the quantum well, the energy level positions of the defect states are located near a quasi-energy level (Eg2) formed by CBM and CBM + 1, the local state density at the CBM and VBM can be effectively adjusted, and the quantum well performance is improved. The electron-hole balance cooling is promoted, the non-radiative recombination effect caused by the deep energy level defect state is avoided, meanwhile, due to the introduction of the defect state, the hot electron cooling time is effectively shortened, the carrier injection and recombination efficiency is enhanced, and compared with a traditional EBL technology, remarkable advantages are shown.

Description

Technical Field

[0001] The present invention belongs to the technical field of semiconductor material preparation, and particularly relates to a method for preparing a wide-bandgap nitride quantum well, a wide-bandgap nitride quantum well, and a wide-bandgap semiconductor device. Background Art

[0002] Wide-bandgap semiconductor nitride materials (bandgap range 3.4 - 6.2 eV) are a type of direct-bandgap semiconductors. Due to their high breakdown field strength, high thermal conductivity, and excellent chemical stability, they are widely used in optoelectronics and power electronics fields. Specifically, in ultraviolet light detection, deep ultraviolet light-emitting diodes (LEDs), lasers, radio frequency power amplifiers, and high-voltage switches, etc., nitride materials have demonstrated important technical value. In typical applications, AlGaN and InGaN-based quantum well structures constitute the core of high-efficiency photodetectors and light-emitting devices. Among them, the design of using low-Al-component AlGaN as the quantum well and high-Al-component AlGaN as the quantum barrier, or low-In-component InGaN quantum wells combined with high-In-component InGaN quantum barriers, is the mainstream solution in the field of optoelectronic devices currently. However, the performance of these devices is still limited by many factors, such as low luminous efficiency, carrier leakage to the p-type region for light emission, and short working life, etc. The reason is that the average free path of electrons in the device is significantly higher than that of holes, which causes the phenomenon of electron leakage to other layers, resulting in low recombination efficiency of electrons in the quantum well.

[0003] The carrier transport asymmetry, whose fundamental reason comes from the energy band structure of nitride materials. The density of states in the conduction band is significantly lower than that in the valence band, which also exacerbates the limitation of device performance. For example, in intrinsic gallium nitride (GaN) and indium nitride (InN), the energy level difference between the conduction band minimum (CBM) and the second conduction band (CBM + 1) is about 2.6 eV, while the valence band is more continuous. This asymmetry significantly prolongs the relaxation time of excited electrons, making the cooling speed of hot electrons much lower than that of holes, resulting in more significant asymmetry in electron-hole cooling in optoelectronic devices. This phenomenon is particularly prominent in high-power and high-frequency applications, directly affecting the response time and device efficiency.

[0004] To address the above problems, traditional solutions mainly rely on introducing a charge blocking layer (EBL) on the top of the quantum well to improve the electron recombination efficiency and suppress electron leakage. However, the use of EBL will cause a series of side effects, such as increasing the total resistance of the device due to the energy band blocking effect, reducing the hole injection efficiency, exacerbating the difficulty of thermal management, and defects caused by lattice mismatch, etc. These problems offset the effect of suppressing electron leakage to a certain extent, limiting the overall performance of the device. Summary of the Invention

[0005] In view of this, the present invention aims to provide a wide-bandgap nitride quantum well, a preparation method thereof, a wide-bandgap nitride quantum well and a wide-bandgap semiconductor device, so as to improve the energy band structure and carrier behavior of the wide-bandgap semiconductor device.

[0006] To achieve the above object, the technical solution of the present invention is realized as follows: One of the purposes of this application is to provide a preparation method of a wide-bandgap nitride quantum well, including the following steps: Growing a quantum well structure, the quantum well structure including a quantum well layer and a quantum barrier layer grown on the quantum well layer; Introducing nitrogen vacancies at the interface of the nitride quantum well at the interface of the quantum well layer and the quantum barrier layer.

[0007] In some embodiments, in the step of growing the quantum well structure, it specifically includes the following steps: Providing a substrate; Growing a GaN bottom layer on the substrate; Growing the quantum well layer and the quantum barrier layer on the GaN bottom layer in sequence.

[0008] In some embodiments, the quantum well layer selects low-composition In x Ga 1-x N, where the In composition x = 15% - 25%, corresponding to a bandgap of 2.8 - 3.2 eV, or Al y Ga 1-y N, where the Al composition y = 10% - 20%, corresponding to a bandgap of 3.8 - 4.2 eV; the quantum barrier layer selects high-composition Al z Ga 1-z N, where the Al composition z = 30% - 80%, corresponding to a bandgap of 4.3 - 6.0 eV, or AlN, where the bandgap is 6.2 eV.

[0009] In some embodiments, the quantum well structure is arranged in multiple layers and stacked in sequence.

[0010] In some embodiments, in the step of providing a substrate, it specifically includes: selecting a c-plane conductive SiC substrate, cleaning it, and then performing nitridation pretreatment to form a GaN buffer layer.

[0011] In some of these embodiments, in the step of growing a GaN-based bottom layer on the substrate, it specifically includes: growing a GaN layer at a temperature of 700 °C to 900 °C and a pressure of 80 to 120 kPa, with a TMGa flow rate of 40 to 60 μmol / min and an NH3 flow rate of 1500 to 2500 sccm. The gas-phase V / III ratio during the growth process is 2000 ± 500, and the growth rate is controlled within the range of 0.8 to 1.2 μm / h.

[0012] In some of these embodiments, in the step of successively growing the quantum well layer and the quantum barrier layer on the GaN-based bottom layer, it specifically includes: using magnetron sputtering, molecular beam epitaxy, or MOCVD to successively grow the quantum well layer and the quantum barrier layer on the GaN-based bottom layer.

[0013] In some of these embodiments, in the step of introducing nitrogen vacancies at the nitride quantum well heterointerfaces at the interfaces of the quantum well layer and the quantum barrier layer, it specifically includes the following steps: Pause the growth at the interface between the quantum barrier layer and the quantum well layer for 20 - 30 seconds. Utilize the nitrogen desorption effect in a vacuum environment to prompt the surface nitrogen atoms to detach, forming a vacancy-rich interface. Use a magnetron sputtering power > 5 kW to increase the plasma energy, enhance the kinetic energy of the sputtering particles, and cause local atomic displacement when hitting the surface of the quantum barrier layer to form point defects; or During the growth stage of the quantum barrier layer, adopt pulsed N2 injection. The flow rate of N2 fluctuates within the range of 100 - 500 sccm with a period of 10 - 60 seconds, and the fluctuation amplitude is ±30% - 50%. Through the periodic fluctuation of the nitrogen flow rate, the local nitrogen atom distribution is induced to be uneven, forming a vacancy enrichment region at the interface between the quantum well layer and the quantum barrier layer.

[0014] In some of these embodiments, in the step of introducing nitrogen vacancies at the nitride quantum well heterointerfaces at the interfaces of the quantum well layer and the quantum barrier layer, it specifically includes the following steps: During the growth stage of the quantum barrier layer, adopt a dynamic NH3 flow rate control technique. Linearly reduce the NH3 flow rate from 100 - 200 sccm / min to 600 - 1000 sccm, and at the same time increase the trimethylaluminum flow rate to 80 - 120 μmol / min, so that the gas-phase V / III ratio during the growth process is reduced to 500 - 800. Adopt a pulsed NH3 interruption process. After growing 1 nm of the quantum barrier layer, turn off NH3 for 5 - 10 seconds, and turn on the vacuum pump extraction system during the interruption to keep the chamber pressure ≤ 1×10 -3Pa, the pumping time is 80%-100% of the interruption time, which promotes the desorption of nitrogen atoms at the interface of the quantum well layer and the quantum barrier layer to form a VN enrichment region; the shift of the N-s state electron binding energy is detected by X-ray photoelectron spectroscopy to quantitatively measure V N The concentration is controlled at 1×10 18 -5×10 19 cm -3 , and deep level transient spectroscopy is used to confirm that the defect states are in the Ec+0.8-1.2 eV range, and high-resolution X-ray diffraction is used to verify that the interface strain remains ≤0.15%; where: the growth temperature is controlled at 800±50 °C, the reaction chamber pressure is maintained at 100±20 kPa, and the growth rate is controlled at 0.8-1.2 μm / h.

[0015] In some embodiments, the growth temperature of the quantum barrier layer is set at 800~950 °C to inhibit the recrystallization ability of nitrogen atoms; after growth, step annealing is performed. First, it is kept warm in the temperature range of 750-850 °C for 8-15 minutes to activate V N formation, and then it is heated to 950-1050 °C at a heating rate of 40-60 °C / min and rapidly cooled to room temperature at a cooling rate of not less than 100 °C / min to regulate the defect stability by thermal activation; the surface of the AlN layer of the quantum barrier is implanted with low-energy nitrogen ions, and the energy range is 5~10 keV, and the dose is controlled at 1×10 13 ~1×10 14 cm -2 .

[0016] The second object of the present application also provides a wide-bandgap nitride quantum well, including a quantum well structure, and the quantum well structure includes a quantum well layer and a quantum barrier layer grown on the quantum well layer; nitrogen vacancies at the heterointerfaces of the nitride quantum wells are introduced at the interfaces of the quantum well layer and the quantum barrier layer.

[0017] The third object of the present application also provides a wide-bandgap semiconductor device, including the wide-bandgap nitride quantum well described above.

[0018] Compared with the prior art, the present invention can achieve the following beneficial effects: The wide-bandgap nitride quantum well, preparation method, wide-bandgap nitride quantum well and wide-bandgap semiconductor device provided by the present application include a quantum well structure, and the quantum well structure includes a quantum well layer and a quantum barrier layer grown on the quantum well layer; nitride quantum well heterointerfacial nitrogen vacancies are introduced at the interface between the quantum well layer and the quantum barrier layer. By introducing precisely designed defect states in the quantum well in the present application, the energy levels of these defect states are located near the quasi-energy level (Eg2) formed by the CBM and CBM+1, which can effectively regulate the local density of states at the CBM and VBM, promote the balanced cooling of electrons and holes, and avoid the non-radiative recombination effect caused by deep-level defect states. At the same time, the introduction of defect states not only effectively reduces the hot electron cooling time, but also enhances the injection and recombination efficiency of carriers, showing significant advantages compared with the traditional EBL technology. Description of the Drawings

[0019] The drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings: Figure 1 It is a step flow chart of the preparation method of the wide-bandgap nitride quantum well provided by the embodiment of the present application.

[0020] Figure 2 It is a schematic structural diagram of introducing point defects in the quantum well provided by the embodiment of the present invention.

[0021] Figure 3 It is a schematic diagram of the quantum well structure and carrier dynamics provided by the embodiment of the present invention.

[0022] Figure 4 It is a schematic diagram of the principle of realizing symmetric injection of carriers in the wide-bandgap nitride quantum well by defect engineering provided by the embodiment of the present invention. Detailed Embodiments

[0023] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the following further details the present invention in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, rather than limiting the present invention. Similar elements in different embodiments are denoted by related similar element numbers. In the following embodiments, many detailed descriptions are provided to enable a better understanding of the present invention. However, those skilled in the art can easily recognize that some of the features can be omitted in different situations, or can be replaced by other elements, materials, or methods. In some cases, some operations related to the present invention are not shown or described in the specification, in order to avoid the core part of the present invention being overwhelmed by excessive description. For those skilled in the art, it is not necessary to describe these related operations in detail, and they can fully understand the related operations based on the description in the specification and the general technical knowledge in the art.

[0024] It should be noted that, without conflict, the embodiments and features in the embodiments of the present invention can be combined with each other to form various embodiments. At the same time, the steps or actions in the method description can also be adjusted in the order that is obvious to those skilled in the art. Therefore, the various sequences in the specification and drawings are only for clearly describing a certain embodiment, and do not mean that they are the necessary sequences, unless it is stated that a certain sequence must be followed.

[0025] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. is based on the orientation or positional relationship shown in the accompanying drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first", "second", etc. may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise stated, the meaning of "a plurality" is two or more.

[0026] In the description of the present invention, it should be noted that unless otherwise clearly specified and defined, the terms "installation", "connection", and "coupling" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood through specific situations.

[0027] The present invention will be described in detail below with reference to the drawings and in conjunction with embodiments.

[0028] As Figure 1 and Figure 2 shown, the method for preparing a wide-bandgap nitride quantum well provided by the embodiment of the present application includes the following steps S110 to S120. The implementation manners of each step are described in detail below.

[0029] Step S110: Grow a quantum well structure, where the quantum well structure includes a quantum well layer and a quantum barrier layer grown on the quantum well layer.

[0030] In this embodiment, the quantum well layer selects low-composition In x Ga 1-x N, where the In composition x = 15% - 25%, corresponding to a bandgap of 2.8 - 3.2 eV, or Al y Ga 1-y N, where the Al composition y = 10% - 20%, corresponding to a bandgap of 3.8 - 4.2 eV; the quantum barrier layer selects high-composition Al z Ga 1-z N, where the Al composition z = 30% - 80%, corresponding to a bandgap of 4.3 - 6.0 eV, or AlN, where the bandgap is 6.2 eV.

[0031] It should be noted that: what is provided in this embodiment is not limited to the above materials, and can also be extended to other wide-bandgap semiconductor materials (such as β-Ga2O3 and ZnO).

[0032] It can be understood that the energy band alignment of the quantum well layer and the quantum barrier layer is a type-I heterojunction, ensuring that the conduction band / valence band offset is sufficient to confine carriers.

[0033] In this embodiment, the quantum well structure is arranged in multiple layers and stacked in sequence.

[0034] Further, in the step of growing the quantum well structure, it specifically includes the following steps: Step S11: Provide a substrate.

[0035] In this embodiment, first, a c-plane conductive SiC substrate is selected and subjected to standard organic cleaning (ultrasonic cleaning in acetone and isopropyl alcohol for 5 minutes each). Subsequently, nitridation pretreatment is carried out in the MOCVD chamber: the substrate surface is subjected to nitrogen saturation adsorption at 800 °C and an ammonia gas flow of 50 kPa for 30 minutes to form a 3-nm-thick GaN buffer layer to optimize stress and lattice matching.

[0036] Step S12: Grow a GaN base layer on the substrate.

[0037] In this embodiment, at a temperature of 700 °C to 900 °C and a pressure of 80 to 120 kPa, a GaN layer is grown with a TMGa flow rate of 40 to 60 μmol / min and an NH3 flow rate of 1500 to 2500 sccm. The gas-phase V / III ratio during the growth process is 2000 ± 500, and the growth rate is controlled within the range of 0.8 to 1.2 μm / h to ensure the flatness of the epitaxial layer and a low dislocation density.

[0038] Step S13: Sequentially grow the quantum well layer and the quantum barrier layer on the GaN base layer.

[0039] In this embodiment, the quantum well layer and the quantum barrier layer are sequentially grown on the GaN base layer by magnetron sputtering, molecular beam epitaxy, or MOCVD.

[0040] Please refer to Figure 3 , which is a schematic diagram of the quantum well structure and carrier dynamics provided by this embodiment.

[0041] In this embodiment, 10 pairs of GaN (2 nm) / AlN (2 nm) quantum wells are grown, such as the quantum well structure shown in Figure 3 ; among them: GaN well layer: temperature 780 °C, ratio of TMIn:TMGa flow rate 1:4, NH3 flow 2000 sccm; AlN well barrier: temperature 900 °C, dynamic NH3 pulse interruption mode for gas inlet; repeat the growth until an MQW stack is formed.

[0042] Step S120: Introduce nitrogen vacancies at the interface of the quantum well layer and the quantum barrier layer at the nitride quantum well heterojunction.

[0043] Please refer to Figure 4 , which is a schematic diagram of the realization of symmetric carrier injection in wide-bandgap nitride quantum wells by defect engineering provided by the present invention. After the MQW growth is completed, low-energy nitrogen ion implantation parameters (energy 5 to 10 keV, dose 5 × 10 13 cm -2 ) are used to ensure the enrichment of VN at the interface without introducing deep damage; subsequently, rapid thermal annealing (RTA) is carried out: keep it at 950 °C in an N2 atmosphere for 30 seconds, and the cooling rate > 100 °C / s to stabilize V through thermal activation.N Defects are detected and secondary lattice damage is repaired. The following is a detailed description of the specific implementation plan.

[0044] In this embodiment, when preparing a GaN / AlN multi-quantum well structure based on metalorganic chemical vapor deposition (MOCVD) technology, in order to introduce nitrogen vacancies at the heterointerface of the nitride quantum well at the interface between the quantum well layer and the quantum barrier layer, the specific process parameters and steps are as follows: During the growth stage of the quantum barrier layer, during the growth stage of the quantum barrier layer, a dynamic NH3 flow control technique is adopted. The NH3 flow rate is linearly reduced from the conventional 2000 sccm to 600 - 1000 sccm at a rate of 100 - 200 sccm / min, and at the same time, the trimethylaluminum flow rate is increased from the conventional 50 μmol / min to 80 - 120 μmol / min, so that the gas-phase V / III ratio during the growth process is reduced from the conventional 2000 - 4000 to 500 - 800. A pulsed NH3 interruption process is adopted. After growing 1 nm of the quantum barrier layer, NH3 is turned off for 5 - 10 seconds, and the vacuum pump extraction system is turned on during the interruption to keep the chamber pressure ≤ 1×10 -3 Pa, and the extraction time is 80% - 100% of the interruption time, prompting the desorption of nitrogen atoms at the interface between the quantum well layer and the quantum barrier layer to form a VN enrichment region; the N-s state electron binding energy shift is detected by X-ray photoelectron spectroscopy to quantitatively control the V N concentration within 1×10 18 -5×10 19 cm -3 , and deep level transient spectroscopy is used to confirm that the defect states are located in the Ec + 0.8 - 1.2 eV range, and high-resolution X-ray diffraction is used to verify that the interface strain remains ≤ 0.15%; where: the growth temperature is controlled at 800 ± 50 °C, the reaction chamber pressure is maintained at 100 ± 20 kPa, and the growth rate is controlled at 0.8 - 1.2 μm / h.

[0045] It can be understood that the dynamic control is the main process and the pulsed interruption is the sub-process: the dynamic NH3 flow control is a global process that runs through the entire growth stage of the quantum barrier layer (i.e., continuously adjusts the NH3 and TMAl flow rates from the start to the end of the growth to control the gas-phase V / III ratio). The pulsed NH3 interruption process is a periodic local process. Based on the dynamic NH3 flow control, an interruption is inserted after growing 1 nm of the quantum barrier layer each time (i.e., "pulsed interruption nested in dynamic control").

[0046] It can be understood that in this embodiment, by regulating the nitrogen source partial pressure and the V / III ratio, reducing the NH3 flow rate or the V / III ratio, since the formation of nitrogen vacancies is directly related to the supply amount of nitrogen atoms, reducing the NH3 flow rate or increasing the proportion of metal organic sources (such as TMAl) can limit the surface migration ability of nitrogen atoms and induce the absence of nitrogen atoms in the lattice. Pulsed gas injection, adopting a PMOCVD-like process, by periodically interrupting the NH3 supply (such as pulsed growth), a locally aluminum-rich environment is formed at the interface, reducing the formation energy of nitrogen vacancies.

[0047] Further, the growth temperature of the quantum barrier layer is set at 800 - 950 °C (lower than the conventional 1000 - 1100 °C) to inhibit the recrystallization ability of nitrogen atoms; after growth, step annealing is carried out. First, keep it at 800 °C for 10 minutes to activate the formation of V N Then, raise the temperature to 1000 °C at a rate of 50 °C / min and rapidly cool it to regulate the defect stability through thermal activation.

[0048] It can be understood that appropriately reducing the substrate temperature during the growth of the quantum barrier layer can inhibit the recrystallization ability of nitrogen atoms and retain unfilled lattice sites. Subsequently, through step annealing (such as gradually rising from 800 °C to 1000 °C), using thermal activation to promote the migration of some nitrogen atoms out of the lattice, selectively stabilizing the VN defects.

[0049] Further, low-energy nitrogen ion implantation is carried out on the surface of the quantum barrier layer, with the energy range of 5 - 10 keV and the dose controlled at 1×10 13 ~1×10 14 cm -2 , combined with a rapid thermal annealing (RTA) process (annealing at 950 °C for 30 seconds in an N2 atmosphere) to repair lattice damage and retain V N defects.

[0050] In this embodiment, when preparing the GaN / AlN multi-quantum well structure by using magnetron sputtering technology, to introduce nitrogen vacancies at the interface of the quantum well layer and the quantum barrier layer, the specific process parameters and steps are as follows: Pause the growth at the interface between the quantum barrier layer and the quantum well layer for several seconds. Utilize the nitrogen desorption effect in a vacuum environment to promote the detachment of surface nitrogen atoms and form a vacancy-rich interface. Increasing the sputtering power (such as the medium-frequency magnetron sputtering power > 5 kW) can increase the plasma energy, enhance the kinetic energy of sputtered particles, and may cause local atomic displacement when hitting the AlN surface, forming point defects. Or; During the growth stage of the quantum barrier layer, pulsed N2 injection is adopted. By periodically fluctuating the nitrogen gas flow rate (such as suddenly dropping from the standard flow rate to 50%), it is possible to induce uneven local nitrogen atom distribution and form a vacancy-enriched region at the interface.

[0051] It should be noted that: Based on first-principles calculations and defect state energy level analysis, this application screens out nitrogen vacancies (V N at the heterointerfaces of nitride quantum wells as the introduction sites of key point defects. The screening criteria include three progressive dimensions: (1) Band matching criterion: Verified by HSE06 hybrid functional calculations, defect configurations with defect state energy levels in the range from the conduction band bottom (CBM) to the CBM + 1 energy level interval (energy window of about 0.5 - 1.2 eV) are preferred. After the introduction of vacancy defects, the local density of states of the quasi-energy band gap in this region can be increased by 40% - 65% (obtained by the integral analysis of the density of states); (2) Lattice dynamics effect: The lattice perturbation caused by nitrogen vacancies can induce phonon branch softening near the Γ point of the Brillouin zone (phonon spectrum calculation shows that the low-frequency phonon mode redshifts up to 12 cm -1 ), significantly enhancing the electron-phonon coupling strength (the Huang-Rhys factor is increased); (3) Defect state suppression mechanism: Verified by time-resolved photoluminescence tests, it is ensured that the defect states do not introduce deep energy level traps, reducing the non-radiative recombination rate to below 1.5×10 16 cm -3 .

[0052] It should be noted that: In addition to the nitride material system, it is further extended to other wide-bandgap semiconductor materials. Such as (1) β -Ga2O3 single crystal: By using 200 keV nitrogen ion irradiation combined with 800 °C annealing process, oxygen vacancies (V O and gallium vacancies (V Ga ) composite defects are formed on the (100) crystal plane. Time-resolved photoluminescence (TRPL) tests show that the carrier cooling time is shortened from 2.3 ns to 0.8 ns, and the non-radiative recombination rate is reduced by 65%; (2) ZnO nanowires: Through 1 MeV electron beam irradiation and 600 °C annealing treatment, zinc interstitial (Zn i ) defect clusters are formed in the c-axis direction. Hall effect tests show that the carrier mobility is increased to 320 cm² / (V·s) (the untreated sample is 180 cm² / (V·s)), and the full width at half maximum of the PL spectrum is narrowed to 42 meV (the control group is 68 meV); (3) 4H-SiC epitaxial layer: Combining 150 keV proton irradiation with 950 °C annealing process, silicon vacancies (V Si and carbon vacancies (V C ) pairs are constructed on the (0001) plane. Deep level transient spectroscopy (DLTS) detects that the defect state density decreases from 5×10 16 cm -3 to 8×10 15 cm -3 , and the reverse leakage current of the device is reduced by two orders of magnitude. The universality of point defect-induced band regulation and cooling time improvement is explored, verifying the feasibility and adaptability of this method for improving the performance of various wide-bandgap semiconductor devices.

[0053] The wide-bandgap nitride quantum well and preparation method provided by this application introduce precisely designed defect states into the quantum well to regulate the local energy band structure and enhance the hot electron cooling rate, thereby improving the symmetry of electron-hole behavior. Specifically, the energy levels of these defect states are located near the quasi-energy level (Eg2) formed by CBM and CBM+1, which can effectively regulate the local density of states at CBM and VBM, promote the balanced cooling of electrons and holes, and avoid the non-radiative recombination effect caused by deep-level defect states.

[0054] In addition, the wide-bandgap nitride quantum well and preparation method provided by this application are based on the interaction between defect states and carrier states in the quantum well. On the one hand, the defect-induced local electric field enhances the energy relaxation of excited electrons through the electron-phonon coupling effect; on the other hand, the distribution of defect states is precisely regulated to ensure that its energy levels match the quantum well band-edge states, thus avoiding the risk of decreasing carrier recombination efficiency. In this way, the introduction of defect states not only effectively reduces the hot electron cooling time, but also enhances the carrier injection and recombination efficiency, showing significant advantages compared with the traditional EBL technology.

[0055] Furthermore, the wide-bandgap nitride quantum well and preparation method provided in this embodiment show through further theoretical and experimental analysis that the strategy of optimizing the quantum well structure using defect engineering can also significantly reduce the local stress and lattice mismatch effects in quantum well devices, improving the long-term reliability and thermal stability of the devices. This innovative design provides a new idea for solving the energy band regulation and carrier management problems of wide-bandgap semiconductor devices, expanding a new direction for device performance optimization.

[0056] The wide-bandgap nitride quantum well and preparation method provided in this embodiment combine defect engineering with quantum structure design, providing a new solution with theoretical significance and practical application potential for the energy band structure regulation and performance optimization of wide-bandgap semiconductor devices. It is expected to be applied in fields such as high-efficiency ultraviolet LEDs, high-frequency power amplifiers, and next-generation photodetectors, promoting the development and application of high-performance wide-bandgap semiconductor devices.

[0057] The above technical solutions of this application will be described in detail below in conjunction with specific embodiments.

[0058] Example 1 The method of the present invention will be further described below in conjunction with the accompanying drawings and embodiments, but the method of the present invention is not limited to the following embodiments.

[0059] 1. Preparation of substrate and buffer layer: First, a c-plane conductive SiC substrate is selected and subjected to standard organic cleaning (ultrasonic cleaning in acetone and isopropyl alcohol for 5 minutes each). Subsequently, nitridation pretreatment is carried out in the MOCVD chamber: the substrate surface is subjected to nitrogen saturation adsorption at 800 °C and an ammonia gas flow of 50 kPa for 30 minutes to form a 3-nm-thick GaN buffer layer to optimize stress and lattice matching.

[0060] 2. Growth of GaN base layer: At 800 °C and 100 kPa, a 2-μm-thick GaN layer is grown with a TMGa flow rate of 50 μmol / min and an NH3 flow rate of 2000 sccm, and the V / III ratio is approximately 2000. The growth rate is controlled within 1.0 μm / h to ensure the flatness of the epitaxial layer and a low dislocation density.

[0061] 3. Epitaxy of GaN / AlN MQW structure: Grow 10 pairs of GaN (2 nm) / AlN (2 nm) quantum wells, as shown in the Figure 3 quantum well structure; among them: GaN well layer: temperature 780 °C, ratio of TMIn:TMGa flow rate 1:4, NH3 flow 2000 sccm; AlN well barrier: temperature 900 °C, dynamic NH3 pulse interruption mode for gas inlet; repeat growth to form an MQW stack.

[0062] 4. Defect activation and post-treatment: After the completion of MQW growth, low-energy nitrogen ion implantation parameters (energy 5 - 10 keV, dose 5×10 13 cm -2 ) are used to ensure the enrichment of V at the interface without introducing deep damage; subsequently, rapid thermal annealing (RTA) is carried out: keep warm at 950 °C for 30 seconds in an N2 atmosphere, and the cooling rate > 100 °C / s, and stabilize the V N defects and repair secondary lattice damage through thermal activation. N

[0063] 5. Sample cutting and electrical preparation: The epitaxial wafer is cut into 5×5 mm 2 small samples using a silicon saw blade, and Ti / Al / Ni / Au (20 / 80 / 20 / 200 nm) electrodes are evaporated on the edges of the small samples, and ohmic contacts are formed by annealing at 450 °C for 1 minute.

[0064] 6. Characterization and testing: Structural analysis: Measure the MQW period and stress distribution using high-resolution X-ray diffraction (HRXRD); Surface morphology: Observe the interface of the defect enrichment area using field emission scanning electron microscopy (FE-SEM); Energy level determination: Measure the N-s electron binding energy using XPS, and analyze the defect energy level density and energy level position using DLTS;​ Optical testing: Room-temperature photoluminescence (PL) and temperature-dependent PL (80 - 300 K) measurements were performed to measure the emission peak position and full width at half maximum; Dynamic relaxation: Femtosecond time-resolved photoluminescence (TRPL) was used to test the electron and hole cooling dynamics. The excitation wavelength was 266 nm, the pulse width was <200 fs, and the time resolution of the measurement was <1 ps; Electrical properties: I-V testing was carried out to measure the leakage current and turn-on voltage in the range of -5 - +5 V.

[0065] 7. Data analysis: By comparing the electron cooling times and the normalized PL intensity trends of different samples, a double-exponential fitting model was used to extract the fast / slow relaxation components and the Huang-Rhys factor, and first-principles calculations were combined to calculate the band reconstruction parameters to achieve the verification of the consistency between theory and experiment, as Figure 4 shown.

[0066] For PL, TRPL, and carrier lifetime tests, the measured hot electron cooling time (as Figure 3 shown) was shortened from the original 2.5 ns to 0.9 ns, achieving a symmetry of ±10% with the hole cooling time; Deep temperature-dependent PL tests showed that the device functioned stably in the range of 300 - 80 K.

[0067] Through the above implementation methods, it was fully demonstrated that by using the atmosphere-temperature-injection co-regulation process, V was controllably introduced at the GaN / AlN MQW interface N , achieving symmetric electron and hole cooling and a significant improvement in carrier injection efficiency.

[0068] It should be understood that various forms of the process shown above can be used, with steps reordered, added, or deleted. For example, the steps described in the disclosure of the present invention can be executed in parallel, sequentially, or in a different order, as long as the desired results of the technical solution disclosed in the present invention can be achieved. This is not limited herein.

[0069] The above specific implementation methods do not constitute a limitation to the protection scope of the present invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for preparing a wide-bandgap nitride quantum well, characterized in that: Including the following steps: Growing a quantum well structure, the quantum well structure including a quantum well layer and a quantum barrier layer grown on the quantum well layer; Introducing nitrogen vacancies at the interface between the quantum well layer and the quantum barrier layer of the nitride quantum well heterointerfaces.

2. The preparation method of the wide bandgap nitride quantum well according to claim 1, wherein: In the step of growing the quantum well structure, it specifically includes the following steps: Providing a substrate; Growing a GaN base layer on the substrate; Sequentially growing the quantum well layer and the quantum barrier layer on the GaN base layer.

3. The preparation method of the wide-bandgap nitride quantum well according to claim 2, wherein: The quantum well layer is selected as low-composition In x Ga 1-x N, where the In composition x = 15% - 25%, corresponding to a bandgap of 2.8 - 3.2 eV, or Al y Ga 1-y N, where the Al composition y = 10% - 20%, corresponding to a bandgap of 3.8 - 4.2 eV; the quantum barrier layer is selected as high-composition Al z Ga 1-z N, where the Al composition z = 30% - 80%, corresponding to a bandgap of 4.3 - 6.0 eV, or AlN, where the bandgap is 6.2 eV.

4. The method for preparing a wide-bandgap nitride quantum well according to claim 1, characterized in that: The quantum well structure is arranged in multiple layers and stacked in sequence.

5. The preparation method of the wide-bandgap nitride quantum well according to claim 2, characterized in that: In the step of providing a substrate, it specifically includes: selecting a c-plane conductive SiC substrate, cleaning it, and then performing nitridation pretreatment to form a GaN buffer layer.

6. The method for preparing a wide bandgap nitride quantum well according to claim 2, wherein: In the step of growing the GaN base layer on the substrate, it specifically includes: at a temperature of 700°C to 900°C and a pressure of 80 to 120 kPa, growing a GaN layer with a TMGa flow rate of 40 to 60 μmol / min and an NH3 flow rate of 1500 to 2500 sccm, with the gas-phase V / III ratio during growth being 2000 ± 500, and the growth rate being controlled within the range of 0.8 to 1.2 μm / h.

7. The method for preparing a wide bandgap nitride quantum well according to claim 2, wherein: In the step of sequentially growing the quantum well layer and the quantum barrier layer on the GaN base layer, it specifically includes: using magnetron sputtering, molecular beam epitaxy, or MOCVD to sequentially grow the quantum well layer and the quantum barrier layer on the GaN base layer.

8. The preparation method of the wide-bandgap nitride quantum well according to claim 7, characterized in that: In the step of introducing nitrogen vacancies at the interface between the quantum well layer and the quantum barrier layer of the nitride quantum well heterointerfaces, it specifically includes the following steps: Pausing growth for 20 - 30 seconds at the interface between the quantum barrier layer and the quantum well layer, using the nitrogen desorption effect in a vacuum environment to cause surface nitrogen atoms to detach, forming a vacancy-rich interface, using a magnetron sputtering power > 5 kW to increase the plasma energy, enhancing the kinetic energy of the sputtering particles, and causing local atomic displacement when hitting the surface of the quantum barrier layer to form point defects; or During the growth stage of the quantum barrier layer, pulsed N2 injection is used, with the flow rate of N2 fluctuating within the range of 100 - 500 sccm with a period of 10 - 60 seconds and a fluctuation amplitude of ±30% - 50% to induce uneven local nitrogen atom distribution and form a vacancy enrichment region at the interface between the quantum well layer and the quantum barrier layer.

9. The method for preparing a wide bandgap nitride quantum well according to claim 8, characterized in that: In the step of introducing nitrogen vacancies at the interface between the quantum well layer and the quantum barrier layer of the nitride quantum well heterointerfaces, it specifically includes the following steps: During the growth stage of the quantum barrier layer, the dynamic NH3 flow control technology is adopted to linearly reduce the NH3 flow rate from 100 - 200 sccm / min to 600 - 1000 sccm, while increasing the trimethylaluminum flow rate to 80 - 120 μmol / min, so that the gas-phase V / III ratio during the growth process is reduced to 500 - 800. During this process, a pulsed NH3 interruption process is periodically embedded. After growing a 1 nm quantum barrier layer, NH3 is turned off for 5 - 10 seconds, and the vacuum pump extraction system is turned on during the interruption to keep the chamber pressure ≤ 1×10 - 3 Pa. The extraction time is 80% - 100% of the interruption time, promoting the desorption of nitrogen atoms at the interface of the quantum well layer and the quantum barrier layer to form a VN-rich region; the N-s state electron binding energy shift is detected by X-ray photoelectron spectroscopy to quantitatively control the V N concentration within 1×10 18 -5×10 19 cm -3 . The deep level transient spectroscopy is used to confirm that the defect states are located in the Ec + 0.8 - 1.2 eV interval, and the interface strain is verified by high-resolution X-ray diffraction to be ≤ 0.15%. Among them: the growth temperature is controlled at 800 ± 50 °C, the reaction chamber pressure is maintained at 100 ± 20 kPa, and the growth rate is controlled at 0.8 - 1.2 μm / h.

10. The method for preparing a wide bandgap nitride quantum well according to claim 9, wherein: The layer growth temperature of the quantum barrier is set to 800~950 °C to suppress the recrystallization ability of nitrogen atoms; after the growth is completed, step annealing is carried out. First, it is kept at 750 - 850 °C for 8 - 15 minutes to activate V N formation, and then it is heated to 950 - 1050 °C at a heating rate of 40 - 60 °C / min and rapidly cooled to room temperature at a cooling rate of not less than 100 °C / min to regulate the defect stability through thermal activation; the surface of the AlN layer of the quantum barrier is implanted with low-energy nitrogen ions, and the energy range is 5~10 keV, and the dose is controlled at 1×10 13 ~1×10 14 cm -2 .

11. A wide-bandgap nitride quantum well, characterized in that, Including a quantum well structure, the quantum well structure including a quantum well layer and a quantum barrier layer grown on the quantum well layer; nitrogen vacancies at the interface between the quantum well layer and the quantum barrier layer are introduced at the nitride quantum well heterointerfaces.

12. A wide bandgap semiconductor device, characterized in that, Including the wide-bandgap nitride quantum well described in claim 11.

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