Wide bandgap nitride quantum well, preparation method and wide bandgap semiconductor device

Abstract

The present invention belongs to the technical field of semiconductor material preparation. The wide bandgap nitride quantum well, preparation method and wide bandgap semiconductor device provided by the present application include a quantum well structure, wherein the quantum well structure includes a quantum well layer and a quantum barrier layer grown on the quantum well layer; nitrogen vacancies at the nitride quantum well heterointerface are introduced at the interface between the quantum well layer and the quantum barrier layer. The present application introduces precisely designed defect states into the quantum well. The energy level positions of these defect states are located near the quasi-energy level (Eg2) formed by CBM and CBM+1, which can effectively regulate the localized state density at CBM and VBM, promote balanced cooling of electrons and holes, and avoid non-radiative recombination effects caused by deep energy 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 carrier injection and recombination efficiency, showing significant advantages compared with traditional EBL technology.

Description

Technical Field

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

[0002] Wide-bandgap semiconductor nitrides (bandgap range 3.4-6.2 eV) are a class of direct-bandgap semiconductors widely used in optoelectronics and power electronics due to their high breakdown field strength, high thermal conductivity, and excellent chemical stability. Specifically, nitride materials have demonstrated significant technological value in ultraviolet (UV) detection, deep-UV light-emitting diodes (LEDs), lasers, radio frequency (RF) power amplifiers, and high-voltage switches. In typical applications, AlGaN and InGaN-based quantum well structures form the core of high-efficiency photodetectors and light-emitting devices. Designs using low-Al content AlGaN as quantum wells and high-Al content AlGaN as quantum barriers, or low-In content InGaN quantum wells combined with high-In content InGaN quantum barriers, are currently the mainstream approaches in optoelectronic devices. However, the performance of these devices is still limited by numerous factors, including low luminescence efficiency, carrier leakage into the p-type region, and short operating lifetimes. This is due to the significantly higher mean free path of electrons than holes within the device, which leads to electron leakage into other layers and low electron recombination efficiency within the quantum well.

[0003] The fundamental cause of carrier transport asymmetry stems from the band structure of nitride materials, where the conduction band density of states is significantly lower than that of the valence band, further limiting device performance. For example, in intrinsic gallium nitride (GaN) and indium nitride (InN), the energy difference between the conduction band bottom (CBM) and the second conduction band (CBM+1) is approximately 2.6 eV, while the valence band is more continuous. This asymmetry significantly prolongs the relaxation time of excited electrons, causing hot electrons to cool much slower than holes, leading to increasingly pronounced electron-hole cooling asymmetry in optoelectronic devices. This phenomenon is particularly pronounced in high-power, high-frequency applications, directly impacting response time and device efficiency.

[0004] Traditional solutions to these problems rely on introducing a charge blocking layer (EBL) on top of the quantum well to improve electron recombination efficiency and suppress electron leakage. However, the use of an EBL can trigger a series of side effects, such as increasing the device's overall resistance due to band blocking, reducing hole injection efficiency, increasing thermal management difficulties, and causing defects due to lattice mismatch. These issues, to a certain extent, offset the electron leakage suppression effect and limit the overall device performance. Summary of the Invention

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

[0006] To achieve the above object, the technical solution created by the present invention is implemented as follows:

[0007] One of the purposes of this application is to provide a method for preparing a wide bandgap nitride quantum well, comprising the following steps:

[0008] Growing a quantum well structure, the quantum well structure comprising a quantum well layer and a quantum barrier layer grown on the quantum well layer;

[0009] Nitrogen vacancies at the nitride quantum well heterointerface are introduced at the interface between the quantum well layer and the quantum barrier layer.

[0010] In some embodiments, the step of growing the quantum well structure specifically includes the following steps:

[0011] providing a substrate;

[0012] growing a GaN base layer on the substrate;

[0013] The quantum well layer and the quantum barrier layer are sequentially grown on the GaN base layer.

[0014] In some embodiments, the quantum well layer is selected to have a low composition of In x Ga 1-x N, where In component x = 15%-25%, corresponding to a band gap of 2.8-3.2 eV or Al y Ga 1-y N, wherein the Al component y = 10%-20%, corresponding to a band gap of 3.8-4.2eV; the quantum barrier layer selects a high component Al z Ga 1-z N, where the Al component z = 30%-80%, corresponding to a band gap of 4.3-6.0 eV or AlN, where the band gap is 6.2 eV.

[0015] In some embodiments, the quantum well structure is a multi-layered structure that is stacked in sequence.

[0016] In some embodiments, the step of providing a substrate specifically includes: selecting a c-plane conductive SiC substrate, cleaning it, and then performing a nitridation pretreatment to form a GaN buffer layer.

[0017] In some embodiments, the step of growing a GaN base layer on the substrate specifically includes: growing a GaN layer at a temperature of 700°C to 900°C and a pressure of 80~120 kPa with a TMGa flow rate of 40~60 μmol / min and an NH3 flow rate of 1500~2500 sccm, the gas phase V / III ratio during the growth process is 2000±500, and the growth rate is controlled in the range of 0.8~1.2 μm / h.

[0018] In some embodiments, the step of sequentially growing the quantum well layer and the quantum barrier layer on the GaN substrate layer specifically includes: sequentially growing the quantum well layer and the quantum barrier layer on the GaN substrate layer by magnetron sputtering, molecular beam epitaxy or MOCVD.

[0019] In some embodiments, the step of introducing nitrogen vacancies at the nitride quantum well heterointerface at the interface between the quantum well layer and the quantum barrier layer specifically includes the following steps:

[0020] Pausing growth for 20-30 seconds at the interface between the quantum barrier layer and the quantum well layer, utilizing the nitrogen desorption effect in a vacuum environment to promote the detachment of surface nitrogen atoms to form a vacancy-rich interface, using a magnetron sputtering power greater than 5 kW to increase plasma energy, thereby enhancing the kinetic energy of the sputtered particles, and causing local atomic displacement when impacting the surface of the quantum barrier layer, thereby forming point defects; or

[0021] During the quantum barrier layer growth stage, pulsed N2 injection is used. The N2 flow rate fluctuates within the range of 100-500 sccm with a period of 10-60 seconds, with a fluctuation amplitude of ±30%-50%. The N2 induces local uneven distribution of nitrogen atoms through periodic nitrogen flow fluctuations, forming a vacancy-enriched region at the interface of the quantum well layer and the quantum barrier layer.

[0022] In some embodiments, the step of introducing nitrogen vacancies at the nitride quantum well heterointerface at the interface between the quantum well layer and the quantum barrier layer specifically includes the following steps:

[0023] During the quantum barrier layer growth stage, a dynamic NH3 flow control technology is used to linearly reduce the NH3 flow rate from 100-200 sccm / min to 600-1000 sccm, while the trimethylaluminum flow rate is increased to 80-120 μmol / min, so that the gas phase V / III ratio during the growth process is reduced to 500-800. A pulsed NH3 interruption process is used, and the NH3 is turned off for 5-10 seconds after each 1 nm quantum barrier layer is grown. During the interruption period, the vacuum pump exhaust system is turned on to maintain the cavity 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-rich region; the Ns state electron binding energy shift is detected by X-ray photoelectron spectroscopy to quantify V N The concentration was controlled at 1×10 18 -5×10 19 cm -3 Deep level transient spectroscopy was used to confirm that the defect state was located in the Ec+0.8-1.2eV range, and high-resolution X-ray diffraction was used to verify that the interface strain remained ≤0.15%; among them: the growth temperature was controlled at 800±50℃, the reaction chamber pressure was maintained at 100±20 kPa, and the growth rate was controlled at 0.8-1.2 μm / h.

[0024] In some embodiments, the growth temperature of the quantum barrier layer is set to 800-950 ° C to suppress the recrystallization ability of nitrogen atoms; after the growth is completed, step annealing is performed, first at a temperature range of 750-850 ° C for 8-15 minutes to activate V N The AlN layer of the quantum barrier is formed by heating the AlN layer at a rate of 40-60°C / min to 950-1050°C and then rapidly cooling the AlN layer to room temperature at a rate of not less than 100°C / min. The defect stability is regulated by thermal activation. Low-energy nitrogen ions are implanted on the AlN layer of the quantum barrier with an energy range of 5-10 keV and a dose controlled at 1×10 13 ~1×10 14 cm -2 .

[0025] The second purpose of the present application is to provide a wide bandgap nitride quantum well, including a quantum well structure, wherein the quantum well structure includes a quantum well layer and a quantum barrier layer grown on the quantum well layer; nitrogen vacancies at the nitride quantum well heterointerface are introduced at the interface between the quantum well layer and the quantum barrier layer.

[0026] The third purpose of this application is to provide a wide bandgap semiconductor device, including the wide bandgap nitride quantum well.

[0027] Compared with the prior art, the present invention can achieve the following beneficial effects:

[0028] 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, wherein the quantum well structure includes a quantum well layer and a quantum barrier layer grown on the quantum well layer; nitrogen vacancies at the nitride quantum well heterointerface are introduced at the interface between the quantum well layer and the quantum barrier layer. The present application introduces precisely designed defect states into the quantum well, and the energy level positions of these defect states are located near the quasi-energy level (Eg2) formed by CBM and CBM+1. This can effectively regulate the local state density at CBM and VBM, promote balanced cooling of electrons and holes, and avoid non-radiative recombination effects caused by deep energy level defect states. At the same time, the introduction of defect states not only effectively reduces the cooling time of hot electrons, but also enhances the injection and recombination efficiency of carriers, showing significant advantages compared with traditional EBL technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The accompanying drawings, which constitute part of the present invention, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0030] Figure 1 This is a flow chart of the steps of the method for preparing a wide bandgap nitride quantum well provided in an embodiment of the present application.

[0031] Figure 2 It is a schematic diagram of the structure of introducing point defects into the quantum well provided by an embodiment of the present invention.

[0032] Figure 3 It is a schematic diagram of the quantum well structure and carrier dynamics provided by an embodiment of the present invention.

[0033] Figure 4 This is a schematic diagram of the principle of achieving symmetric carrier injection into wide-bandgap nitride quantum wells through defect engineering provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below 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 and do not constitute a limitation to the present invention. Similar elements in different embodiments use associated similar element numbers. In the following embodiments, many detailed descriptions are intended to enable the present invention to be better understood. 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. This is to avoid the core part of the present invention being overwhelmed by too much description. For those skilled in the art, it is not necessary to describe these related operations in detail. They can fully understand the related operations based on the description in the specification and the general technical knowledge in the art.

[0035] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments of the present invention can be combined with each other to form various implementation methods. At the same time, the steps or actions in the method description can also be interchanged or adjusted in a manner that is obvious to those skilled in the art. Therefore, the various orders in the description and the drawings are only for the purpose of clearly describing a certain embodiment and are not intended to be a required order, unless otherwise specified that a certain order must be followed.

[0036] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are 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, and therefore cannot be understood as limiting 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 number of the indicated technical features. Therefore, features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0037] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to internal connections between two components. Those skilled in the art can understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0038] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments.

[0039] like Figure 1 and Figure 2 As shown, the method for preparing a wide bandgap nitride quantum well provided in an embodiment of the present application includes the following steps S110 to S120, and the implementation method of each step is described in detail below.

[0040] Step S110 : growing a quantum well structure, wherein the quantum well structure includes a quantum well layer and a quantum barrier layer grown on the quantum well layer.

[0041] In this embodiment, the quantum well layer is selected from low-component In x Ga 1-x N, where In component x = 15%-25%, corresponding to a band gap of 2.8-3.2 eV or Al y Ga 1-y N, wherein the Al component y = 10%-20%, corresponding to a band gap of 3.8-4.2eV; the quantum barrier layer selects a high component Al z Ga 1-z N, where the Al component z = 30%-80%, corresponding to a band gap of 4.3-6.0 eV or AlN, where the band gap is 6.2 eV.

[0042] It should be noted that the materials provided in this embodiment are not limited to the above materials, but can also be extended to other wide bandgap semiconductor materials (such as β-Ga2O3 and ZnO).

[0043] It can be understood that the energy bands of the quantum well layer and the quantum barrier layer are arranged as a type I heterojunction, ensuring that the conduction band / valence band offset is sufficient to confine carriers.

[0044] In this embodiment, the quantum well structure is a multi-layered structure that is stacked in sequence.

[0045] Furthermore, the step of growing the quantum well structure specifically includes the following steps:

[0046] Step S11: providing a substrate.

[0047] In this example, a c-plane conductive SiC substrate was first selected and subjected to standard organic cleaning (acetone and isopropanol ultrasonic cleaning for 5 minutes each). Subsequently, a nitridation pretreatment was performed in an MOCVD chamber: nitrogen was saturated on the substrate surface at 800°C and 50kPa ammonia flow for 30 minutes to form a 3nm thick GaN buffer layer to optimize stress and lattice matching.

[0048] Step S12: growing a GaN base layer on the substrate.

[0049] In this implementation, the GaN layer was grown 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 was 2000±500, and the growth rate was controlled in the range of 0.8 to 1.2 μm / h to ensure the flatness and low dislocation density of the epitaxial layer.

[0050] Step S13: sequentially growing the quantum well layer and the quantum barrier layer on the GaN substrate layer.

[0051] In this embodiment, the quantum well layer and the quantum barrier layer are sequentially grown on the GaN substrate layer by magnetron sputtering, molecular beam epitaxy or MOCVD.

[0052] See also Figure 3 , which is a schematic diagram of the quantum well structure and carrier dynamics provided in this embodiment.

[0053] In this embodiment, 10 pairs of GaN (2nm) / AlN (2nm) quantum wells are grown, such as Figure 3 The quantum well structure shown in the figure; wherein: GaN well layer: temperature 780℃, TMIn:TMGa flow ratio 1:4, NH3 flow 2000sccm; AlN well barrier: temperature 900℃, dynamic NH3 pulse interruption mode intake; repeated growth to form an MQW stack.

[0054] Step S120: introducing nitrogen vacancies at the nitride quantum well heterointerface at the interface between the quantum well layer and the quantum barrier layer.

[0055] See also Figure 4 , which is the principle diagram of the defect engineering provided by the present invention to achieve symmetric carrier injection into wide bandgap nitride quantum wells. After the MQW growth is completed, low-energy nitrogen ion implantation parameters (energy 5~10keV, dose 5×10 13 cm -2 ), to ensure interface VN enrichment without introducing deep damage; followed by rapid thermal annealing (RTA): 950 ° C in N2 atmosphere for 30 seconds, cooling rate > 100 ° C / s, to stabilize V by thermal activationN The following details the specific implementation scheme for this.

[0056] In this embodiment, when preparing a GaN / AlN multi-quantum well structure based on metal organic chemical vapor deposition (MOCVD) technology, in order to introduce nitrogen vacancies at the interface of the quantum well layer and the quantum barrier layer at the nitride quantum well heterointerface, the specific process parameters and steps are as follows:

[0057] During the quantum barrier layer growth stage, a dynamic NH3 flow control technology is used to linearly reduce the NH3 flow rate from the conventional 2000sccm to 600-1000sccm at a rate of 100-200sccm / min, and at the same time increase the trimethylaluminum flow rate from the conventional 50μmol / min to 80-120μmol / 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 used, and the NH3 is turned off for 5-10 seconds after each 1nm quantum barrier layer is grown. During the interruption, the vacuum pump exhaust system is turned on to maintain the cavity pressure ≤1×10 -3 Pa, 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-rich region; the Ns state electron binding energy shift is detected by X-ray photoelectron spectroscopy to quantify V N The concentration was controlled at 1×10 18 -5×10 19 cm -3 Deep level transient spectroscopy was used to confirm that the defect state was located in the Ec+0.8-1.2 eV range, and high-resolution X-ray diffraction was used to verify that the interface strain remained ≤0.15%; among them: the growth temperature was controlled at 800±50℃, the reaction chamber pressure was maintained at 100±20kPa, and the growth rate was controlled at 0.8-1.2μm / h.

[0058] It can be understood that dynamic control is the main process, and pulse interruption is a sub-process: Dynamic NH3 flow control is a global process that runs throughout the entire quantum barrier layer growth stage (i.e., continuously adjusting the NH3 and TMAl flow rates from the beginning to the end of growth to control the gas-phase V / III ratio). The pulsed NH3 interruption process is a periodic local process. Based on dynamic NH3 flow control, an interruption is inserted after each 1nm of quantum barrier layer growth (i.e., "nested pulse interruption within dynamic control").

[0059] It can be understood that this embodiment reduces the NH3 flow rate or V / III ratio by regulating the nitrogen source partial pressure and V / III ratio. Since the formation of nitrogen vacancies is directly related to the nitrogen atom supply, reducing the NH3 flow rate or increasing the metal organic source (such as TMAl) can limit the surface migration ability of nitrogen atoms and induce nitrogen atom vacancies in the crystal lattice. Pulsed gas injection, using a PMOCVD-like process, periodically interrupts the NH3 supply (e.g., pulsed growth), creating a localized aluminum-rich environment at the interface and reducing the formation energy of nitrogen vacancies.

[0060] Furthermore, the growth temperature of the quantum barrier layer is set to 800~950℃ (lower than the conventional 1000~1100℃) to suppress the recrystallization ability of nitrogen atoms; after the growth is completed, step annealing is performed, first at 800℃ for 10 minutes to activate V N The defect stability was regulated by thermal activation after heating to 1000℃ at a rate of 50℃ / min and cooling rapidly.

[0061] It is understood that appropriately lowering the substrate temperature during quantum barrier layer growth can suppress the recrystallization ability of nitrogen atoms, preserving unfilled lattice sites. Subsequent step-wise annealing (e.g., gradually increasing the temperature from 800°C to 1000°C) utilizes thermal activation to induce some nitrogen atoms to migrate out of the lattice, selectively stabilizing VN defects.

[0062] Furthermore, low-energy nitrogen ion implantation was performed on the surface of the quantum barrier layer with an energy range of 5-10 keV and a dose controlled at 1×10 13 ~1×10 14 cm -2 , combined with a rapid thermal annealing (RTA) process (950 ° C annealing for 30 seconds in N2 atmosphere) to repair lattice damage and retain V N defect.

[0063] In this embodiment, when a GaN / AlN multi-quantum well structure is prepared using magnetron sputtering technology, in order to introduce nitrogen vacancies at the interface of the quantum well layer and the quantum barrier layer at the nitride quantum well heterointerface, the specific process parameters and steps are as follows:

[0064] Pausing growth for a few seconds at the interface between the quantum barrier layer and the quantum well layer, utilizing the nitrogen desorption effect in a vacuum environment to cause the surface nitrogen atoms to detach, forming a vacancy-rich interface. Increasing the sputtering power (e.g., medium-frequency magnetron sputtering power > 5 kW) can increase the plasma energy, enhancing the kinetic energy of the sputtered particles. When they impact the AlN surface, they may cause local atomic displacement and form point defects. Or;

[0065] Pulsed N2 injection is used during the quantum barrier layer growth stage. Through periodic nitrogen flow fluctuations (such as a sudden drop from the standard flow to 50%), local nitrogen atom distribution can be induced to be uneven, forming a vacancy-rich region at the interface.

[0066] It should be pointed out that: Based on first-principles calculations and defect state energy level analysis, this application screens out nitrogen vacancies (V N ) as the key point defect introduction site. The screening criteria include three progressive dimensions: (1) Band matching criterion: verified by HSE06 hybrid functional calculation, the defect configuration with the defect state energy level located in the range from the conduction band bottom (CBM) to the CBM+1 energy level (energy window of about 0.5-1.2 eV) is preferred. The local state density of the quasi-level band gap in this region can be increased by 40%-65% after the introduction of vacancy defects (obtained by state density integral analysis); (2) Lattice dynamics effect: the lattice perturbation caused by nitrogen vacancies can induce the softening of the phonon branch near the Γ point in the Brillouin zone (phonon spectrum calculation shows that the low-frequency phonon mode redshift reaches 12 cm -1 ), significantly enhancing the electroacoustic coupling strength (Huang-Rhys factor improvement); (3) Defect state suppression mechanism: using time-resolved photoluminescence testing to verify that defect states do not introduce deep energy level traps, reducing the non-radiative recombination rate to 1.5×10 16 cm -3 the following.

[0067] It should be pointed out that: in addition to the nitride material system, it has also been further extended to other wide bandgap semiconductor materials. For example (1) β -Ga2O3 single crystal: 200keV nitrogen ion irradiation combined with 800℃ annealing process is used to form oxygen vacancies (V O ) and gallium vacancies (V Ga ) Recombination defects, time-resolved photoluminescence (TRPL) test shows that the carrier cooling time is shortened from 2.3ns to 0.8ns, and the non-radiative recombination rate is reduced by 65%; (2) ZnO nanowires: After 1MeV electron beam irradiation and 600℃ annealing, zinc gaps (Zn) are formed in the c-axis direction. i ) defect clusters, Hall effect test shows that the carrier mobility is improved to 320 cm² / (V·s) (untreated sample is 180 cm² / (V·s)), and the PL spectrum half-maximum width is narrowed to 42 meV (control group 68 meV); (3) 4H-SiC epitaxial layer: Combined with 150keV proton irradiation and 950℃ annealing process, silicon vacancies (V Si ) and carbon vacancies (V C ) for deep level transient spectroscopy (DLTS), the defect state density was detected to be from 5×10 16 cm -3 Down to 8×10 15 cm -3, the device reverse leakage current is reduced by two orders of magnitude. The universality of point defect-induced bandgap modulation and cooling time improvement is explored, and the feasibility and adaptability of this method for improving the performance of various wide-bandgap semiconductor devices are verified.

[0068] The wide-bandgap nitride quantum well and its preparation method provided in this application improve the symmetry of electron-hole behavior by introducing precisely designed defect states into the quantum well, regulating the localized band structure and increasing the hot electron cooling rate. Specifically, these defect states are located near the quasi-energy level (Eg2) formed by the CBM and CBM+1, effectively regulating the localized state density at the CBM and VBM, promoting balanced electron-hole cooling, and avoiding non-radiative recombination effects caused by deep-level defect states.

[0069] 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 local electric field induced by the defect enhances the energy relaxation of excited electrons through electroacoustic coupling; on the other hand, the distribution of defect states is precisely controlled to ensure that their energy levels match the quantum well band edge states, thereby avoiding the risk of decreased carrier recombination efficiency. In this way, 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 to traditional EBL technology.

[0070] Furthermore, further theoretical and experimental analysis of the wide-bandgap nitride quantum well and its fabrication method provided in this embodiment demonstrates that the strategy of optimizing the quantum well structure through defect engineering can significantly reduce local stress and lattice mismatch effects in quantum well devices, thereby improving the long-term reliability and thermal stability of the devices. This innovative design provides a new approach to addressing the energy band modulation and carrier management issues of wide-bandgap semiconductor devices, and opens up new avenues for device performance optimization.

[0071] The wide-bandgap nitride quantum well and its fabrication method provided in this embodiment, by combining defect engineering with quantum structure design, provides a novel approach with both theoretical significance and practical application potential for band structure control and performance optimization of wide-bandgap semiconductor devices. These approaches are expected to be applied in areas such as high-efficiency ultraviolet LEDs, high-frequency power amplifiers, and next-generation photodetectors, thereby promoting the development and application of high-performance wide-bandgap semiconductor devices.

[0072] The above technical solutions of the present application are described in detail below with reference to specific embodiments.

[0073] Example 1

[0074] The method of the present invention is further described below with reference to the accompanying drawings and embodiments, but the method of the present invention is not limited to the following embodiments.

[0075] 1. Preparation of substrate and buffer layer:

[0076] First, a c-face conductive SiC substrate was selected and subjected to standard organic cleaning (acetone and isopropanol ultrasonic cleaning for 5 minutes each). Subsequently, a nitridation pretreatment was performed in an MOCVD chamber: nitrogen saturated adsorption of the substrate surface was carried out at 800°C and 50kPa ammonia flow for 30 minutes to form a 3nm thick GaN buffer layer to optimize stress and lattice matching.

[0077] 2.GaN substrate layer growth:

[0078] A 2-μm-thick GaN layer with a V / III ratio of approximately 2000 was grown at 800°C and 100 kPa with a TMGa flow rate of 50 μmol / min and an NH3 flow rate of 2000 sccm. The growth rate was controlled within 1.0 μm / h to ensure epitaxial layer flatness and low dislocation density.

[0079] 3.GaN / AlN MQW structure epitaxy:

[0080] Grow 10 pairs of GaN (2nm) / AlN (2nm) quantum wells, such as Figure 3 The quantum well structure shown in the figure; wherein: GaN well layer: temperature 780℃, TMIn:TMGa flow ratio 1:4, NH3 flow 2000sccm; AlN well barrier: temperature 900℃, dynamic NH3 pulse interruption mode intake; repeated growth to form an MQW stack.

[0081] 4. Defect activation and post-processing:

[0082] After the MQW growth is completed, low-energy nitrogen ion implantation parameters (energy 5~10keV, dose 5×10 13 cm -2 ), to ensure that the interface V N enrichment without introducing deep damage; followed by rapid thermal annealing (RTA): 950℃ for 30 seconds in N2 atmosphere, cooling rate >100℃ / s, to stabilize V by thermal activation N defects and repair secondary lattice damage.

[0083] 5. Sample cutting and electrical preparation:

[0084] Use silicon saw blade to cut epitaxial wafer into 5×5mm 2 A small sample was prepared, and Ti / Al / Ni / Au (20 / 80 / 20 / 200 nm) electrodes were evaporated on the edge of the sample, and annealed at 450 ° C for 1 min to form an ohmic contact.

[0085] 6. Characterization and testing:

[0086] Structural analysis: High-resolution X-ray diffraction (HRXRD) was used to measure the MQW period and stress distribution;

[0087] Surface morphology: Field emission scanning electron microscopy (FE-SEM) was used to observe the interface of the defect-rich area;

[0088] Energy level determination: XPS measures Ns electron binding energy, and DLTS analyzes defect energy level density and energy level position;

[0089] Optical testing: Room temperature photoluminescence (PL) and temperature-dependent PL (80-300K) measurements of luminescence peak position and half-width;

[0090] Dynamic relaxation: Femtosecond time-resolved photoluminescence (TRPL) tests the cooling dynamics of electrons and holes, with an excitation wavelength of 266 nm, a pulse width of <200 fs, and a test time resolution of <1 ps;

[0091] Electrical performance: IV test measures leakage current and turn-on voltage in the range of -5-+5V.

[0092] 7. Data Analysis:

[0093] The electron cooling time and PL intensity normalization trends of different samples were compared, and the fast / slow relaxation components and Huang-Rhys factors were extracted using a double exponential fitting model. The energy band reconstruction parameters were calculated in combination with first-principles methods to verify the consistency between theory and experiment. Figure 4 shown.

[0094] PL, TRPL and carrier lifetime tests were conducted to measure the hot electron cooling time (e.g. Figure 3 The device’s thermal conductivity (PL) is shortened from 2.5 ns to 0.9 ns, achieving ±10% symmetry with the hole cooling time. Deep temperature-dependent PL testing shows that the device functions stably in the 300–80 K range.

[0095] The above implementation method fully proves that the atmosphere-temperature-injection coordinated control process can be used to controllably introduce V at the GaN / AlNMQW interface. N , achieving electron and hole cooling symmetry and significantly improving carrier injection efficiency.

[0096] It should be understood that the various forms of the processes shown above can be used to reorder, add, or delete steps. For example, the steps described in the present disclosure can be performed in parallel, sequentially, or in a different order, as long as the desired results of the technical solutions disclosed in the present disclosure can be achieved. This is not limited herein.

[0097] The above specific embodiments do not limit the scope of protection of the present invention. Those skilled in the art will appreciate that various modifications, combinations, sub-combinations, and substitutions may be made based on design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention are intended to be included within the scope of protection of the present invention.

Claims

1. A method for preparing a wide bandgap nitride quantum well, characterized by: The steps include: Growing a quantum well structure, the quantum well structure comprising a quantum well layer and a quantum barrier layer grown on the quantum well layer; Introducing nitrogen vacancies at the nitride quantum well heterointerface at the interface between the quantum well layer and the quantum barrier layer; The steps of growing the quantum well structure specifically include 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 substrate layer; The step of introducing nitrogen vacancies at the nitride quantum well heterointerface at the interface between the quantum well layer and the quantum barrier layer specifically includes the following steps: During the quantum barrier layer growth stage, a dynamic NH3 flow control technology is used to linearly reduce the NH3 flow rate from 100-200 sccm / min to 600-1000 sccm, while the trimethylaluminum flow rate is increased 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 inserted. After growing a 1 nm quantum barrier layer, the NH3 is turned off for 5-10 seconds, and the vacuum pump exhaust system is turned on during the interruption to maintain the cavity pressure ≤1×10 - 3 Pa, 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 nitrogen vacancies V N enriched region; the Ns state electron binding energy shift was detected by X-ray photoelectron spectroscopy, and the nitrogen vacancy V was quantified. N The concentration was controlled at 1×10 18 -5×10 19 cm -3 Deep level transient spectroscopy was used to confirm that the defect state was located in the Ec+0.8-1.2eV range, and high-resolution X-ray diffraction was used to verify that the interface strain remained ≤0.15%; among them: the growth temperature was controlled at 800±50℃, the reaction chamber pressure was maintained at 100±20 kPa, and the growth rate was controlled at 0.8-1.2μm / h.

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

3. The method for preparing a wide bandgap nitride quantum well according to claim 1, wherein: The quantum well structure is multi-layered and stacked in sequence.

4. The method for preparing a wide bandgap nitride quantum well according to claim 1, wherein: The step of providing a substrate specifically includes: selecting a c-plane conductive SiC substrate, cleaning it, and then performing a nitridation pretreatment to form a GaN buffer layer.

5. The method for preparing a wide bandgap nitride quantum well according to claim 1, wherein: The step of growing a GaN base layer on the substrate 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, wherein 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.

6. The method for preparing a wide bandgap nitride quantum well according to claim 1, wherein: The step of sequentially growing the quantum well layer and the quantum barrier layer on the GaN substrate layer specifically includes: sequentially growing the quantum well layer and the quantum barrier layer on the GaN substrate layer by magnetron sputtering, molecular beam epitaxy or MOCVD.

7. The method for preparing a wide bandgap nitride quantum well according to claim 6, wherein: The step of introducing nitrogen vacancies at the nitride quantum well heterointerface at the interface between the quantum well layer and the quantum barrier layer specifically includes the following steps: Pausing growth for 20-30 seconds at the interface between the quantum barrier layer and the quantum well layer, utilizing the nitrogen desorption effect in a vacuum environment to promote the detachment of surface nitrogen atoms to form a vacancy-rich interface, using a magnetron sputtering power greater than 5 kW to increase plasma energy, thereby enhancing the kinetic energy of the sputtered particles, and causing local atomic displacement when impacting the surface of the quantum barrier layer, thereby forming point defects; or During the quantum barrier layer growth stage, pulsed N2 injection is used, and the N2 flow rate fluctuates within the range of 100-500 sccm with a period of 10-60 seconds, with a fluctuation amplitude of ±30%-50%, so as to induce local uneven distribution of nitrogen atoms and form a vacancy-enriched region at the interface of the quantum well layer and the quantum barrier layer.

8. The method for preparing a wide bandgap nitride quantum well according to claim 1, wherein: The quantum barrier layer growth temperature is set to 800-950 ° C to suppress the recrystallization ability of nitrogen atoms; after the growth is completed, step annealing is performed, first at 750-850 ° C for 8-15 minutes to activate V N The AlN layer of the quantum barrier is formed by heating the AlN layer at a rate of 40-60°C / min to 950-1050°C and then rapidly cooling the AlN layer to room temperature at a rate of not less than 100°C / min. The defect stability is regulated by thermal activation. Low-energy nitrogen ions are implanted on the AlN layer of the quantum barrier with an energy range of 5-10 keV and a dose controlled at 1×10 13 ~1×10 14 cm -2 .

9. A wide bandgap nitride quantum well, characterized in that: The method for preparing a wide bandgap nitride quantum well according to any one of claims 1 to 8 is used to prepare the wide bandgap nitride quantum well; the method comprises a quantum well structure, wherein the quantum well structure comprises a quantum well layer and a quantum barrier layer grown on the quantum well layer; nitrogen vacancies at the nitride quantum well heterointerface are introduced at the interface between the quantum well layer and the quantum barrier layer.

10. A wide bandgap semiconductor device, characterized in that: Comprising the wide bandgap nitride quantum well as claimed in claim 9.

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