Semiconductor structure with barrier layer comprising aluminum

Abstract

The invention discloses a semiconductor structure with an aluminum nitride single crystal-containing barrier layer and a growth method thereof, and belongs to the technical field of semiconductors, and the semiconductor structure comprises a substrate, a buffer layer, a GaN channel layer and an aluminum nitride single crystal barrier layer which are sequentially laminated; the heterojunction comprises a GaN channel layer and an aluminum nitride single crystal barrier layer; alN ultra-thin quantum wells which are periodically stacked are arranged in the aluminum nitride single-crystal barrier layer, and the proportional relation between the first vertical distance between the AlN ultra-thin quantum wells and the grid electrode and the second vertical distance between the AlN ultra-thin quantum wells and the GaN channel layer conforms to the quantum mechanics tunneling effect and the semiconductor polarization field theory. The AlN ultrathin quantum well comprises a plurality of quantum well units, each quantum well unit comprises an AlN thin layer and an Al0. 5Ga0. 5N thin layer which are arranged in a laminated mode, and the stacking period of the AlN ultrathin quantum well is smaller than 5. Two-dimensional electron gas is formed in the GaN channel layer.

Description

Technical Field

[0001] The present invention belongs to the field of semiconductor technology, and particularly relates to a semiconductor structure having a barrier layer containing single-crystalline aluminum nitride and a method for growing the same. Background Art

[0002] The single-crystalline aluminum nitride barrier layer is a key functional layer in a semiconductor heterojunction structure designed based on single-crystalline aluminum nitride material. Its core function is to optimize device performance through the polarization effect and high-barrier characteristics. Semiconductor structures play an irreplaceable role in modern electronics and electrical engineering. It determines the performance of devices, including response speed, power consumption, thermal management, etc. An efficient semiconductor structure can support high-frequency and high-power applications and is applicable to multiple fields such as computers, communication devices, and sensors. Moreover, the selection of semiconductor materials and structures has an important impact on power efficiency, operating temperature range, and device reliability. Therefore, in the design of high-efficiency electronic devices, the optimization of semiconductor structures is crucial.

[0003] However, due to the relatively low heterojunction bandgap difference in existing semiconductors, non-ideal effects occur when electrons or holes cross the bandgap under high electric fields and high-frequency operation. Carriers may leak or scatter, reducing the switching efficiency and stability of the device. In high-power applications, this situation is easily affected by thermal effects and power losses, limiting its performance and reliability in high-frequency and high-power scenarios. Summary of the Invention

[0004] In order to solve the problems in the prior art that due to the relatively low heterojunction bandgap difference in existing semiconductors, non-ideal effects occur when electrons or holes cross the bandgap under high electric fields and high-frequency operation, carriers may leak or scatter, reducing the switching efficiency and stability of the device. In high-power applications, this situation is easily affected by thermal effects and power losses, limiting its performance and reliability in high-frequency and high-power scenarios, and seriously affecting the high-frequency performance of the device, the present invention provides a semiconductor structure having a barrier layer containing single-crystalline aluminum nitride and a method for growing the same.

[0005] In a first aspect, the present invention provides a semiconductor structure having a barrier layer containing single-crystalline aluminum nitride, including: a substrate, a buffer layer, a heterojunction, a source electrode, a gate electrode, and a drain electrode; The heterojunction includes a GaN channel layer and a single-crystalline aluminum nitride barrier layer; The substrate, the buffer layer, the GaN channel layer, and the single-crystalline aluminum nitride barrier layer are sequentially stacked; Both the source electrode and the drain electrode are in contact with the GaN channel layer; The gate electrode is in contact with the single-crystalline aluminum nitride barrier layer; There is a periodically stacked AlN ultra-thin quantum well in the aluminum nitride single crystal barrier layer, and the proportional relationship between the first vertical distance from the AlN ultra-thin quantum well to the gate and the second vertical distance from the AlN ultra-thin quantum well to the GaN channel layer conforms to the quantum mechanical tunneling effect and the semiconductor polarization field theory; The AlN ultra-thin quantum well includes a plurality of quantum well units, and each quantum well unit includes an AlN thin layer and an Al 0.5 Ga 0.5 thin layer stacked on top of each other, and the stacking period of the AlN ultra-thin quantum well is less than 5; Under the polarization effect of the heterojunction, a two-dimensional electron gas for providing a conductive channel is formed in the GaN channel layer.

[0006] In a second aspect, the present invention provides a method for growing a semiconductor structure having a barrier layer containing aluminum nitride single crystal, the method comprising: S1: Pretreat the substrate in a MOCVD chamber; S2: Grow a buffer layer on the pretreated substrate; S3: Adjust the temperature to 1080 °C and the TMG flow rate to 100 μmol / min, and grow the GaN channel layer at a growth rate of 1.2 μm / h; S4: Grow the aluminum nitride single crystal barrier layer at a gradually changing temperature according to the proportional relationship between the first vertical distance and the second vertical distance; S5: Adjust the temperature to 900 °C, switch the TMA flow rate and the TMG flow rate according to the periodic stacking rule, and grow the AlN ultra-thin quantum well, wherein at the end of each stacking period, the temperature is adjusted to 700 °C in a nitrogen environment for in-situ annealing for a preset duration; S6: Grow the remaining thickness of the aluminum nitride single crystal barrier layer at a gradually changing temperature; S7: Grow the source electrode, the gate electrode and the drain electrode respectively to obtain the semiconductor structure.

[0007] Compared with the prior art, the present invention has at least the following beneficial technical effects: In the embodiments of the present invention, the combination of the aluminum nitride single-crystal barrier layer and the GaN channel layer efficiently utilizes the wide bandgap characteristic of aluminum nitride, enhances the heterojunction bandgap difference, optimizes the electron transport channel, improves the conductivity, thereby effectively enhancing the isolation effect of electrons at the heterojunction interface, reducing the leakage and scattering of carriers, forming an efficient two-dimensional electron gas, and thus improving the switching efficiency and stability of the device. Secondly, the periodic stacked AlN ultra-thin quantum wells in the aluminum nitride single-crystal barrier layer precisely control the electron behavior by optimizing the quantum mechanical tunneling effect and the semiconductor polarization field theory, reducing the non-ideal effects caused by the bandgap difference. At the same time, the structural design of the AlN ultra-thin quantum wells reduces carrier scattering, effectively reduces power loss, and improves the thermal management performance, enhancing the reliability and stability of the device in high-frequency and high-power applications. Therefore, this semiconductor structure has stronger performance advantages in the high-frequency and high-power fields and is suitable for a wider range of high-performance electronic device applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The above characteristics, technical features, advantages and their implementation manners of the present invention will be further described below in a clear and understandable manner in combination with the drawings in the preferred embodiments.

[0009] Figure 1 is a schematic structural diagram of a semiconductor structure provided by the present invention having a barrier layer including an aluminum nitride single crystal; Figure 2 is a schematic structural diagram of a heterojunction provided by the present invention; Figure 3 is a schematic structural diagram of an AlN ultra-thin quantum well provided by the present invention; Figure 4 is a schematic structural diagram of a T-shaped gate provided by the present invention; Figure 5 is a schematic flow chart of a growth method of a semiconductor structure provided by the present invention having a barrier layer including an aluminum nitride single crystal. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0010] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the specific embodiments of the present invention will be described below with reference to the drawings. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings and other embodiments can be obtained.

[0011] Embodiment 1 In one embodiment, referring to the accompanying drawings of the specification Figure 1 shows a schematic structural diagram of a semiconductor structure provided by the present invention having a barrier layer including an aluminum nitride single crystal. Referring to the accompanying drawings of the specification Figure 2, showing a schematic structural diagram of the heterojunction provided by the present invention. Figure 1 and Figure 2 displays a semiconductor structure that includes a source electrode, a gate electrode, and a drain electrode, and the hierarchical structure is stacked in a specific order. The core is a GaN (gallium nitride) channel layer that provides a conductive path for electrons. Above the GaN channel layer is a single-crystal aluminum nitride (AlN) blocking layer that helps isolate the channel layer and prevent carrier leakage. Periodically stacked quantum wells (alternating thin layers of AlN and Al0.5Ga0.5N) are provided within this AlN layer. By means of quantum effects, the carrier behavior is optimized, carrier scattering is reduced, thereby improving the performance of the device. This structure utilizes the heterojunction polarization effect between GaN and AlN to form a high-density two-dimensional electron gas (2DEG) in the GaN channel layer, further enhancing conductivity and device performance, and is particularly suitable for high-frequency and high-power applications.

[0012] Refer to the attached Figure 3 , showing a schematic structural diagram of the AlN ultra-thin quantum well provided by the present invention.

[0013] Figure 3 displays periodically stacked AlN ultra-thin quantum wells, and this structure shows periodically stacked AlN ultra-thin quantum wells. Each layer includes alternately stacked thin layers of AlN and Al0.5Ga0.5N. By alternately stacking these materials, a thin-layer structure with quantum confinement effects is formed, thereby controlling the behavior of electrons at the quantum scale. The AlN thin layer has a wide bandgap and can effectively isolate carriers, while the Al0.5Ga0.5N thin layer helps to adjust the electronic properties of the quantum well. The design of periodic stacking can enhance the quantum effect, improve the conductive characteristics of carriers and the overall performance of the device.

[0014] The semiconductor structure provided by the present invention having a blocking layer containing single-crystal aluminum nitride includes: a substrate, a buffer layer, a heterojunction, a source electrode, a gate electrode, and a drain electrode.

[0015] Among them, the heterojunction refers to an interface structure composed of two different semiconductor materials (such as GaN and aluminum nitride). Due to their different bandgaps, the formed heterojunction can control the flow and distribution of carriers, thereby affecting the performance of semiconductor devices.

[0016] The heterojunction includes a GaN channel layer and a single-crystal aluminum nitride blocking layer.

[0017] The substrate, buffer layer, GaN channel layer, and single-crystal aluminum nitride blocking layer are sequentially stacked.

[0018] Both the source electrode and the drain electrode are in contact with the GaN channel layer.

[0019] The gate electrode is in contact with the single-crystal aluminum nitride blocking layer.

[0020] An AlN ultra-thin quantum well with periodic stacking is provided in the aluminum nitride single-crystal barrier layer. The proportional relationship between the first vertical distance of the AlN ultra-thin quantum well from the gate and the second vertical distance from the GaN channel layer conforms to the quantum mechanical tunneling effect and the semiconductor polarization field theory.

[0021] Among them, the AlN ultra-thin quantum well refers to an extremely thin quantum structure formed by alternating stacks of aluminum nitride (AlN) materials and other semiconductor materials (such as Al0.5Ga0.5N). The characteristic of the quantum well is that the movement of electrons in it is restricted to a very narrow area, usually at the nanometer thickness level. In this way, the behavior of electrons will exhibit quantum mechanical effects. AlN as a quantum well material has a relatively wide bandgap, which means it can effectively isolate carriers, reduce carrier scattering, and enhance carrier stability. By setting the AlN ultra-thin quantum well, the carrier transport path can be optimized, the electron mobility can be improved, and efficient current transport can be achieved. This structure plays an important role in improving the performance of semiconductor devices in applications such as high frequency and high power.

[0022] It can be understood that the tunneling effect is a quantum mechanical effect. When electrons or other particles face an energy barrier that seems insurmountable, they may still pass through this barrier, resulting in the transmission of electron flow. The polarization field theory is an electric field effect caused by the bandgap difference of materials in a heterojunction. This effect helps to form a high density of carriers at the interface and improve the conductivity of the device. It should be noted that this structure sets an AlN ultra-thin quantum well with periodic stacking in the aluminum nitride single-crystal barrier layer and uses precise design to control the distance ratio between the gate and the GaN channel layer. This proportional relationship conforms to the quantum mechanical tunneling effect and the semiconductor polarization field theory, thereby optimizing the electron transport path, improving the formation efficiency of two-dimensional electron gas, reducing carrier scattering and leakage, and enhancing the conductivity and stability of the device. Through this design, the performance of the device can be effectively improved in high-frequency and high-power applications.

[0023] The AlN ultra-thin quantum well includes multiple quantum well units, and each quantum well unit includes an AlN thin layer and an Al 0.5 Ga 0.5 GaN thin layer stacked. The stacking period of the AlN ultra-thin quantum well is less than 5.

[0024] Among them, the stacking period value of the AlN ultra-thin quantum well is 3, 4 or 5. The AlN ultra-thin quantum well in this structure consists of multiple quantum well units, and each unit contains alternately stacked AlN thin layers and Al0.5Ga0.5N thin layers. This alternating stack design optimizes the carrier transport characteristics by adjusting the bandgap difference of different materials. A stacking period less than 5 means that the number of stacked layers of these quantum well units is less, thus reducing the material complexity while ensuring a strong manifestation of quantum effects, effectively improving the electron transport efficiency and overall performance of the device.

[0025] Under the polarization effect of the heterojunction, a two-dimensional electron gas for providing a conductive channel is formed in the GaN channel layer.

[0026] Among them, the two-dimensional electron gas refers to a two-dimensional electron conductive channel formed at the heterojunction interface due to polarization effect or quantum effect. The movement of electrons in this channel is limited to two planar dimensions, greatly improving the current transmission ability.

[0027] It should be noted that the semiconductor structure combines the aluminum nitride single crystal blocking layer with the GaN channel layer, utilizes the heterojunction effect between the two, and optimizes the electron conductive channel. In this structure, periodically stacked AlN ultra-thin quantum wells are arranged in the aluminum nitride single crystal blocking layer. These quantum wells precisely control the distance between the gate and the GaN channel layer through design, and use the quantum mechanical tunneling effect and semiconductor polarization field theory to enable electrons to form an efficient conductive channel in the two-dimensional electron gas. Due to the wide bandgap characteristic of aluminum nitride, the carrier isolation effect at the interface is enhanced, carrier leakage and scattering are reduced, and the switching speed and stability of the device are improved. At the same time, the quantum well structure reduces energy loss and scattering effects, optimizes thermal management, and enhances the performance of the device in high-frequency and high-power applications. Therefore, this structure has a higher power density, better thermal conductivity performance, and stronger anti-scattering ability, and is suitable for a wider range of high-performance electronic devices.

[0028] Compared with the prior art, the present invention has at least the following beneficial technical effects: In the embodiments of the present invention, the combination of the aluminum nitride single crystal barrier layer and the GaN channel layer efficiently utilizes the wide bandgap characteristic of aluminum nitride, enhances the heterojunction bandgap difference, optimizes the electron transport channel, improves the conductivity, thereby effectively enhancing the isolation effect of electrons at the heterojunction interface, reducing the leakage and scattering of carriers, forming an efficient two-dimensional electron gas, and thus improving the switching efficiency and stability of the device. Secondly, the periodically stacked AlN ultra-thin quantum wells in the aluminum nitride single crystal barrier layer precisely control the electron behavior by optimizing the quantum mechanical tunneling effect and the semiconductor polarization field theory, reducing the non-ideal effects caused by the bandgap difference. At the same time, the structural design of the AlN ultra-thin quantum wells reduces carrier scattering, effectively reduces power loss, and improves the thermal management performance, enhancing the reliability and stability of the device in high-frequency and high-power applications. Therefore, this semiconductor structure has stronger performance advantages in the high-frequency and high-power fields and is suitable for a wider range of high-performance electronic device applications.

[0029] In a possible implementation, the substrate includes a Si substrate and a sapphire substrate.

[0030] It should be noted that the substrate can be selected as a Si (silicon) substrate or a sapphire substrate. The Si substrate has a lower cost and wide applications, and is suitable for large-scale production. The sapphire substrate has better thermal conductivity and higher high-temperature resistance, and is suitable for high-power and high-frequency device applications, which can improve the stability and performance of the device.

[0031] In a possible implementation, the buffer layer is an AlGaN buffer layer.

[0032] It should be noted that the AlGaN buffer layer can effectively alleviate the lattice mismatch problem between the substrate and the GaN layer, reduce stress, avoid crack generation, and improve the quality of the GaN layer. At the same time, AlGaN has good thermal conductivity, which helps the device to dissipate heat and improves the performance and reliability in high-frequency and high-power applications.

[0033] In a possible implementation, the thickness ratio between the AlN thin layer and the Al 0.5 Ga 0.5 0.5Ga0.5N thin layer is 5:3.

[0034] It should be noted that the thickness ratio of the AlN thin layer to the Al0.5Ga0.5N thin layer is 5:3. This ratio helps to optimize the electronic properties of the quantum well and ensure the best performance of the quantum effect. By adjusting the ratio of these two materials, the carrier transport and scattering characteristics can be effectively controlled, improving the performance and stability of the device, especially in high-frequency and high-power applications.

[0035] In a possible implementation, the proportional relationship between the first vertical distance and the second vertical distance is specifically: ; where represents the first vertical distance, represents the second vertical distance, represents the range of values [ 0 . 5 , 1 . 2 ] of the empirical coefficient, represents the AlN dielectric constant, represents the piezoelectric polarization field strength at the AlN / GaN interface, represents the Schottky barrier height generated by the contact between the gate metal and the aluminum nitride single crystal blocking layer, represents the reduced Planck constant, represents the effective mass of electrons in AlN, represents the Thomas-Fermi screening length, which is a characteristic length describing the shielding ability of free carriers in a semiconductor against an external electric field, represents the GaN dielectric constant, represents the electric field strength at a distance from the gate within the aluminum nitride single crystal blocking layer, represents the initial electric field strength at the contact interface between the aluminum nitride single crystal blocking layer and the gate, represents the thickness of the aluminum nitride single crystal blocking layer, represents the maximum gate voltage.

[0036] where the specific value of the Thomas-Fermi screening length is 25 nm. Optionally, α can take any value within the range [ 0 . 5 , 1 . 2 ] such as 0.6. , represents the free electron mass.

[0037] Specifically, the calculation of the proportional relationship between the first vertical distance (d 1 ) and the second vertical distance (d 2 ) helps to optimize the electric field distribution between the gate and the aluminum nitride single crystal blocking layer. Through this proportional relationship, the electric field strength between the aluminum nitride single crystal blocking layer and the GaN channel layer can be controlled, thereby precisely regulating the formation of the two-dimensional electron gas (2DEG). This proportional relationship combines the quantum mechanical tunneling effect and the semiconductor polarization field theory, which can reduce carrier leakage and scattering, ensuring the efficient and stable electron transport path. In addition, this design can optimize the thermal management and power loss of the device in high-frequency and high-power applications, reduce the leakage current, improve the switching efficiency and the long-term reliability of the device. By accurately calculating the ratio of d1 to d2, the device performance can be maximally improved in the design, especially for electronic devices in the high-frequency and high-power fields, ensuring their efficient stability in practical applications.

[0038] In a possible implementation manner, the proportional relationship formula between the thickness of the AlN ultra-thin quantum well and the thickness of the heterojunction is specifically: ; Wherein, and respectively represent the thickness of the AlN ultra-thin quantum well and the thickness of the heterojunction, represents the interface characteristic parameter, represents the effective mass of electrons in AlN, represents the interface roughness factor measured by AFM, represents the thickness of the AlN / GaN interface transition layer calibrated by TEM, represents the piezoelectric polarization field strength of the AlN / GaN interface, represents the Thomas-Fermi screening length, which is the characteristic length describing the shielding ability of free carriers in a semiconductor to an external electric field, represents the dielectric constant of AlN, represents the Schottky barrier height generated by the contact between the gate metal and the aluminum nitride single crystal blocking layer.

[0039] Specifically, the actual heterojunction interface is not an ideal abrupt change, but there is a transition region with a gradual change in material composition. That is, the thickness of this transition region affects the formation and performance of the 2DEG. An overly thick transition layer may lead to a weakened polarization effect, affecting the electron concentration and mobility. The thickness of the heterojunction plays a key role in semiconductor devices because it determines the interface characteristics between different materials and affects the migration and scattering of carriers. By reasonably calculating the ratio of the thickness of the AlN ultra-thin quantum well to the thickness of the heterojunction, the behavior of electrons in the interface region can be precisely controlled, and the formation of the two-dimensional electron gas (2DEG) can be optimized. Calculating in combination with the thickness of the heterojunction can ensure the full play of quantum effects and control the thickness of the transition layer, thereby reducing the electric field shielding effect, improving the carrier mobility, and maximizing the stability and efficiency of the device.

[0040] Refer to the attached Figure 4 of the specification, which shows the structural schematic diagram of the T-shaped gate provided by the present invention.

[0041] Figure 4The structure of the T-shaped gate in the present invention is shown. In this embodiment, a rectangular aluminum nitride covering layer is provided between the T-shaped gate and the single-crystal aluminum nitride blocking layer. The thickness of this covering layer is less than the first vertical distance between the gate and the GaN channel layer. The width and length of the rectangular aluminum nitride covering layer are the same as those of the gate, which can effectively enhance the control ability of the gate, optimize the electric field distribution, and reduce carrier leakage. Through this design, the leakage current can be effectively reduced, the switching efficiency and stability of the device can be improved, thereby enhancing the performance of the semiconductor device in high-frequency and high-power applications.

[0042] In a possible embodiment, the gate is a T-shaped gate.

[0043] A rectangular aluminum nitride covering layer is provided between the T-shaped gate and the single-crystal aluminum nitride blocking layer, wherein the thickness of the rectangular aluminum nitride covering layer is less than the first vertical distance, and the width and length of the rectangular aluminum nitride covering layer are the same as those of the gate root.

[0044] Among them, the gate root is the finger-like structure part in the gate design. It enhances the control ability of the gate through contact with the aluminum nitride (AlN) layer, thereby optimizing the electric field distribution and reducing carrier leakage. This design helps to improve the performance of the device, especially enhances the control of the two-dimensional electron gas (2DEG), reduces power loss, and improves the switching efficiency.

[0045] It should be noted that the rectangular aluminum nitride covering layer between the T-shaped gate and the single-crystal aluminum nitride blocking layer can effectively enhance the gate control ability. The thickness of this covering layer is less than the vertical distance between the gate and the GaN channel layer, and is the same as the width and length of the gate. Through this design, the barrier under the gate is locally thickened, which can effectively reduce the leakage current, reduce power loss and improve the stability of the device. At the same time, the drift of the threshold voltage (Vth) is less than 0.1V, ensuring high-precision control during long-term operation.

[0046] Specifically, this semiconductor structure including a single-crystal aluminum nitride blocking layer significantly improves performance in high-frequency and high-power applications by combining a GaN channel layer and an AlN blocking layer. The single-crystal aluminum nitride blocking layer effectively prevents carrier leakage and optimizes the electron behavior through periodically stacked AlN ultra-thin quantum wells, reducing scattering and enhancing conductivity. This structure utilizes the hetero-junction polarization effect between GaN and AlN to form a high-density two-dimensional electron gas (2DEG), enhancing the conductivity and stability of the device. By precisely controlling the distance between the gate and the aluminum nitride blocking layer and exerting quantum effects, the electron mobility can be increased, power loss can be reduced, and thermal management can be optimized. In addition, the combination of the T-shaped gate design and the rectangular aluminum nitride covering layer further improves the control ability of the gate, reduces the leakage current, and ensures long-term stability and high-precision control.

[0047] Example 2 In one embodiment, refer to the appended description Figure 5 , which shows a schematic flow chart of a method for growing a semiconductor structure having a barrier layer including single-crystalline aluminum nitride provided by the present invention.

[0048] The method for growing a semiconductor structure having a barrier layer including single-crystalline aluminum nitride provided by the present invention includes: S1: Pretreat the substrate in a MOCVD chamber.

[0049] Specifically, the pretreatment process is as follows: First, ultrasonically clean with acetone / isopropanol (10 min). Then, etch with an HF:H 2 O = 1:10 solution for 30 seconds (to remove the oxide layer). Finally, after drying with nitrogen at 120°C, perform in-situ annealing at 1200°C for 30 minutes.

[0050] S2: Grow a buffer layer on the pretreated substrate.

[0051] S3: Adjust the temperature to 1080°C and the TMG flow rate to 100 μmol / min, and grow a GaN channel layer at a growth rate of 1.2 μm / h.

[0052] Among them, TMG (trimethylgallium) is an organogallium compound commonly used as a gallium source in the metalorganic chemical vapor deposition (MOCVD) process to synthesize compound semiconductor materials such as GaN and GaAs. In step S3, the temperature is adjusted to 1080°C, and the GaN channel layer is grown using a TMG flow rate of 100 μmol / min. During this process, using the metalorganic chemical vapor deposition (MOCVD) technique, the GaN channel layer is deposited at a growth rate of 1.2 μm / h. This temperature and flow rate setting helps to ensure high-quality deposition of the GaN layer, control the growth rate to achieve the required film thickness and uniformity.

[0053] S4: Grow a single-crystalline aluminum nitride barrier layer at a gradually changing temperature according to the proportional relationship between the first vertical distance and the second vertical distance.

[0054] In a possible implementation manner, S4 is specifically: Adjust the temperature to 850°C and grow a single-crystalline aluminum nitride barrier layer with a first preset thickness. Adjust the temperature to 950°C and grow a single-crystalline aluminum nitride barrier layer with a second preset thickness, where the proportional relationship between the first preset thickness and the second preset thickness is 1:6.

[0055] It should be noted that first, the temperature is adjusted to 850 °C to grow an aluminum nitride single crystal barrier layer with a first preset thickness. Then, the temperature is increased to 950 °C to grow an aluminum nitride single crystal barrier layer with a second preset thickness, and the ratio of the thicknesses of these two layers is 1:6. This strategy of growing at a gradually changing temperature can optimize the quality and performance of the aluminum nitride single crystal barrier layer. By adjusting the growth temperature and thickness ratio, the lattice matching and stress distribution between layers can be effectively controlled, thereby improving the stability and conductivity of the device, and at the same time contributing to the realization of an ideal two-dimensional electron gas (2DEG) structure.

[0056] S5: Adjust the temperature to 900 °C, and switch the flow rates of TMA and TMG according to the periodic stacking rule to grow an AlN ultra-thin quantum well. Wherein, at the end of each stacking cycle, the temperature is adjusted to 700 °C in a nitrogen environment for in-situ annealing for a preset duration.

[0057] Among them, TMA (trimethylaluminum) is an organoaluminum compound widely used in the metalorganic chemical vapor deposition (MOCVD) process as an aluminum source material. TMA decomposes at high temperatures and releases aluminum atoms, which react with the nitrogen source to form aluminum nitride (AlN) or other aluminum-based materials. Due to its high reactivity, TMA is usually used to grow materials such as AlN and AlGaN, especially in semiconductor devices and quantum structures, and can effectively control the thickness and quality of the thin film. In step S5, the temperature is adjusted to 900 °C, and the flow rates of TMA (organoaluminum) and TMG (organogallium) are switched according to the periodic stacking rule to grow an AlN ultra-thin quantum well. After each stacking cycle is completed, the temperature is reduced to 700 °C in a nitrogen environment for in-situ annealing for a preset period of time. This process helps to optimize the structure of the quantum well, enhance the quantum effect, improve the electronic properties of the material, and at the same time the annealing treatment helps to remove internal stress and improve the thin film quality.

[0058] It should be noted that those skilled in the art can set the size of the preset duration according to actual needs, and the present invention does not limit this here. Optionally, the preset duration can be set to 60 s.

[0059] S6: Grow the remaining thickness of the aluminum nitride single crystal barrier layer at a gradually changing temperature.

[0060] S7: Grow the source electrode, gate electrode, and drain electrode respectively to obtain a semiconductor structure.

[0061] In a possible implementation manner, the post-treatment process of the aluminum nitride single crystal barrier layer is: annealing the aluminum nitride single crystal barrier layer at 1400 °C in a nitrogen environment.

[0062] It should be noted that the post-treatment process of the aluminum nitride single-crystal barrier layer is an annealing treatment at a high temperature of 1400°C in a nitrogen environment. This annealing process helps to remove stress, defects, and non-uniformities within the aluminum nitride layer, promoting crystal rearrangement and quality improvement. Through this high-temperature annealing, the crystal structure of the aluminum nitride single-crystal barrier layer can be significantly improved, enhancing its conductivity and stability, and ensuring the reliability and efficiency of the device in high-frequency and high-power applications.

[0063] In the actual application process, the advantage of this growth method lies in its precise control of the growth process of each layer. By gradually adjusting the temperature and flow rate, the quality and performance of the aluminum nitride single-crystal barrier layer, GaN channel layer, and AlN ultra-thin quantum well are optimized. Through gradient temperature control and periodic stacking, the lattice matching and stress distribution of each layer can be effectively adjusted to ensure high-quality bonding between layers, reducing defects and non-uniformities. In addition, through timely in-situ annealing treatment and high-temperature annealing, stress can be removed and the film quality can be improved, thereby enhancing the conductivity, stability, and reliability of the device. Especially in high-frequency and high-power applications, it shows higher performance, enhancing the long-term stability and efficiency of the device.

[0064] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0065] The above embodiments only represent several implementation manners of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention.

Claims

1. A semiconductor structure having a barrier layer comprising an aluminum nitride single crystal, characterized in that include: Substrate, buffer layer, heterojunction, source, gate and drain; The heterojunction includes a GaN channel layer and an aluminum nitride single crystal barrier layer; The substrate, the buffer layer, the GaN channel layer and the aluminum nitride single crystal barrier layer are stacked in sequence; The source electrode and the drain electrode are both arranged in contact with the GaN channel layer; The gate is arranged in contact with the aluminum nitride single crystal barrier layer; The aluminum nitride single crystal barrier layer is provided with periodically stacked AlN ultra-thin quantum wells, and the proportional relationship between the first vertical distance of the AlN ultra-thin quantum well from the gate and the second vertical distance from the GaN channel layer conforms to the quantum mechanics tunneling effect and semiconductor polarization field theory; The AlN ultra-thin quantum well comprises a plurality of quantum well units, each of which comprises a stacked AlN thin layer and an Al 0.5 Ga 0.5 N thin layer, the stacking period of the AlN ultra-thin quantum well is less than 5; Under the polarization effect of the heterojunction, a two-dimensional electron gas for providing a conductive channel is formed in the GaN channel layer.

2. The semiconductor structure having a barrier layer comprising aluminum nitride single crystal according to claim 1, characterized in that: The substrate includes a Si substrate and a sapphire substrate.

3. The semiconductor structure having a barrier layer comprising aluminum nitride single crystal according to claim 1, characterized in that: The buffer layer is an AlGaN buffer layer.

4. The semiconductor structure having a barrier layer comprising aluminum nitride single crystal according to claim 1, characterized in that: AlN thin layer thickness and Al 0.5 Ga 0.5 The ratio between the thickness of N thin layers is 5:

3.

5. The semiconductor structure having a barrier layer comprising aluminum nitride single crystal according to claim 1, characterized in that: The proportional relationship between the first vertical distance and the second vertical distance is specifically: ； in, represents the first vertical distance, represents the second vertical distance, Indicates the value range is The empirical coefficient of represents the dielectric constant of AlN, represents the piezoelectric polarization field strength at the AlN / GaN interface, It represents the Schottky barrier height generated by the contact between the gate metal and the aluminum nitride single crystal barrier layer. represents the reduced Planck constant, represents the effective mass of electrons in AlN, The Thomas-Fermi screening length is the characteristic length that describes the shielding ability of free carriers in semiconductors against external electric fields. represents the GaN dielectric constant, Indicates the distance between the aluminum nitride single crystal barrier layer and the gate The electric field strength at represents the initial electric field strength at the interface between the aluminum nitride single crystal barrier layer and the gate, represents the thickness of the aluminum nitride single crystal barrier layer, Indicates the maximum gate voltage.

6. The semiconductor structure having a barrier layer comprising aluminum nitride single crystal according to claim 1, characterized in that: The specific proportional relationship between the thickness of the AlN ultra-thin quantum well and the thickness of the heterojunction is: ； in, and represent the thickness of AlN ultra-thin quantum well and heterojunction, respectively. Indicates interface characteristic parameters, represents the effective mass of electrons in AlN, represents the interface roughness factor obtained by AFM measurement, represents the thickness of the AlN / GaN interface transition layer calibrated by TEM, represents the piezoelectric polarization field strength at the AlN / GaN interface, The Thomas-Fermi screening length is the characteristic length that describes the shielding ability of free carriers in semiconductors against external electric fields. represents the dielectric constant of AlN, Represents the Schottky barrier height generated by the contact between the gate metal and the aluminum nitride single crystal barrier layer.

7. The semiconductor structure having a barrier layer comprising aluminum nitride single crystal according to claim 1, characterized in that: The gate is a T-shaped gate; A rectangular aluminum nitride covering layer is arranged between the T-shaped gate and the aluminum nitride single crystal barrier layer, wherein the thickness of the rectangular aluminum nitride covering layer is less than the first vertical distance, and the width and length of the rectangular aluminum nitride covering layer are the same as those of the gate heel.

8. A method for growing a semiconductor structure having a barrier layer comprising aluminum nitride single crystal according to any one of claims 1 to 7, characterized in that: Methods include: S1: pre-treating the substrate in a MOCVD chamber; S2: growing the buffer layer on the pretreated substrate; S3: adjusting the temperature to 1080° C., the TMG flow rate to 100 μmol / min, and growing the GaN channel layer at a growth rate of 1.2 μm / h; S4: growing the aluminum nitride single crystal barrier layer at a gradual temperature according to a proportional relationship between the first vertical distance and the second vertical distance; S5: adjusting the temperature to 900° C., switching the TMA flow rate and the TMG flow rate according to the periodic stacking rule, and growing the AlN ultra-thin quantum well, wherein at the end of each stacking cycle, the temperature is adjusted to 700° C. in a nitrogen environment for in-situ annealing for a preset time; S6: growing the remaining thickness of the aluminum nitride single crystal barrier layer at a gradual temperature; S7: Growing the source electrode, the gate electrode and the drain electrode respectively to obtain the semiconductor structure.

9. The method for growing a semiconductor structure having a barrier layer comprising aluminum nitride single crystal according to claim 8, characterized in that: The S4 is specifically: adjusting the temperature to 850°C to grow an aluminum nitride single crystal barrier layer of a first preset thickness; adjusting the temperature to 950°C to grow an aluminum nitride single crystal barrier layer of a second preset thickness, wherein the ratio of the first preset thickness to the second preset thickness is 1:

6.

10. The method for growing a semiconductor structure having a barrier layer comprising aluminum nitride single crystal according to claim 8, characterized in that: The post-treatment process of the aluminum nitride single crystal barrier layer is: annealing the aluminum nitride single crystal barrier layer at 1400° C. in a nitrogen environment.

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