Group III nitride device and preparation method thereof
By introducing a periodic nanostructured gas-sensitive layer and gate modulation into a GaN-based gas sensor, the problems of low sensitivity and slow response at room temperature are solved, achieving high-sensitivity and fast-response gas detection, suitable for industrial safety and environmental monitoring.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-25
- Publication Date
- 2026-03-10
AI Technical Summary
Existing GaN-based gas sensors have low sensitivity and slow response at room temperature. Traditional noble metal thin-film gate materials exhibit performance degradation at low temperatures, and the interaction area between the sensing layer and gas molecules is limited, resulting in low adsorption site density.
Using group III nitride devices, a buffer layer, channel layer, barrier layer and gas-sensitive layer are formed on the substrate. The gas-sensitive layer has a periodic nanostructure, including nanopores or nanogrooves, which increases the gas adsorption area and generates a geometric confinement effect under light. Combined with gate control of 2DEG concentration, a highly efficient catalytic reaction for gas detection is achieved.
It significantly improves the sensitivity and response speed of gas sensors, reduces the detection limit, avoids the need for high-temperature operating environments, and enhances the stability and selective detection capabilities of the device.
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Figure CN121633221A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of semiconductor technology, and in particular to a group III nitride device and a preparation method thereof. BACKGROUND
[0002] In recent years, with the increasingly stringent requirements of environmental protection, the continuous development of industrial production, and the high attention of society to health and safety, various detection technologies, such as gas detection, have become increasingly important. Gas sensors are widely used in industrial safety, environmental monitoring, medical diagnosis and other fields, can detect toxic and harmful, flammable and explosive gases in industrial equipment, can monitor air quality, and can also detect respiratory diseases. Under this background, the demand for accurate detection and identification of gas molecules continues to grow, which has promoted the rapid development of sensing technology.
[0003] At present, GaN materials have wide application prospects in the field of sensing and detection due to their wide band gap, high electron mobility and other excellent characteristics. GaN-based devices can be widely used for gas detection due to their high sensitivity and extremely low detection limit, and also have unique advantages in the field of sensing and detection due to their high thermal stability and chemical stability. In the GaN HEMT structure, due to the spontaneous polarization and piezoelectric polarization effect, there is a high mobility and high concentration of 2DEG at the AlGaN / GaN heterojunction interface. The thin AlGaN barrier layer helps to improve the interface sensitivity, and the high mobility of 2DEG can enhance the sensitivity of the electrical response. This characteristic improves the sensitivity of the sensor and reduces the detection limit, making it have a significant advantage in sensing and detection.
[0004] In addition, the gate sensitive material of the GaN HEMT device is a key factor affecting the gas sensing performance of the device. At present, noble metal thin films such as Pt and Pd are usually used as gate materials. However, devices using noble metal thin films as gate materials usually require high-temperature environments. If the sensing performance will be greatly reduced at room temperature or lower temperature, and the interaction area between the traditional sensitive layer and the gas molecules is limited, the adsorption site density is low, which seriously restricts the improvement of sensitivity. Therefore, developing a gas sensor with high-density adsorption sites and high sensitivity, high response speed, and low detection limit at room temperature has become the key target of current research. SUMMARY
[0005] The purpose of the present application is to overcome the problems of low sensitivity and slow response speed of the gas sensor in the prior art, and to provide a group III nitride device and a preparation method thereof.
[0006] In a first aspect, a group III nitride device is provided, comprising: a substrate and a buffer layer, a channel layer, a barrier layer, and a first gas-sensitive layer sequentially formed on the substrate. A source and a drain are disposed on the barrier layer. The first gas-sensitive layer is disposed between the source and drain of the device. The first gas-sensitive layer is located between the source and drain. The first gas-sensitive layer is made of a material sensitive to a target gas. The first gas-sensitive layer has periodically arranged nanostructures formed by an etching process. The periodic nanostructures include nanopore structures and / or nanogroove structures. The nanopore structures form a porous structure along a direction perpendicular to the surface of the first gas-sensitive layer. The nanogroove structures extend along a direction parallel to the surface of the first gas-sensitive layer to form a strip-like structure. The periodic nanostructures are used to increase the gas adsorption area and generate a geometric confinement effect on illumination, thereby improving the gas-sensitive response performance. The device achieves efficient detection of the target gas through the synergistic amplification effect of the gas reaction catalyzed by the first gas-sensitive layer with the periodic nanostructures and the 2DEG at the channel.
[0007] In some possible implementations, the group III nitride device further includes a gate disposed on the barrier layer and between the source and drain, with the first gas-sensitive layer disposed between the source and gate or between the gate and drain. This structure, by introducing a gate, achieves effective electrical control over the 2DEG concentration, thereby significantly improving the device's detection sensitivity.
[0008] In some possible implementations, a second gas-sensitive layer is further disposed on the upper surface of the gate. This second gas-sensitive layer is made of a material sensitive to the target gas and has a periodic nanostructure. The nanopore structure forms a porous structure along a direction perpendicular to the surface of the second gas-sensitive layer, and the nanogroove structure extends along a direction parallel to the surface of the second gas-sensitive layer to form a strip-like structure. The second gas-sensitive layer covers the upper surface of the gate, and its boundary is located inside the gate sidewall or substantially aligned with the gate sidewall, without extending to the barrier layer outside the gate. This structure achieves synergistic enhancement of on-gate modulation and channel modulation, thereby greatly improving the device's response amplitude and detection sensitivity.
[0009] In some possible implementations, the substrate is made of one or more of the following materials: silicon, sapphire, silicon carbide, gallium nitride, diamond, aluminum nitride, and QST, etc.
[0010] In some possible implementations, the materials of the buffer layer, channel layer, and barrier layer are selected from different materials among GaN, AlGaN, InGaN, InAlN, AlInGaN, and other group III nitrides, or at least one of the materials containing different dopants are selected, wherein the interface between the channel layer and the barrier layer forms a 2DEG channel.
[0011] In some possible implementations, both the first gas-sensitive layer and the second gas-sensitive layer are composed of one or more of the following materials: nitride materials, metal oxides and two-dimensional transition metal dichalcogenides, wherein the first gas-sensitive layer or the second gas-sensitive layer of different materials can generate a large number of electron-hole pairs under light illumination.
[0012] The nitride material is composed of any one or more of the group III nitride materials such as gallium nitride (GaN), aluminum gallium nitride (AlGaN), and indium aluminum nitride (InAlN); the metal oxide is composed of any one or more of the metal oxide materials such as tin dioxide (SnO2), zinc oxide (ZnO), and titanium dioxide (TiO2); and the two-dimensional transition metal disulfide is composed of any one or more of the materials such as molybdenum disulfide (MoS2) and tungsten disulfide (WS2).
[0013] In some possible implementations, the periodic nanostructure includes nanopore structures and / or nanogroove structures. The nanopore structure has a circular, elliptical, polygonal, or other irregularly shaped etched cross-section in a direction parallel to the surface of the first or second gas-sensitive layer. The nanogroove structure has a rectangular, trapezoidal, V-shaped, or other irregularly shaped elongated structure in a direction parallel to the surface of the first or second gas-sensitive layer. The periodic nanostructure has a periodic arrangement characteristic, forming an array distribution, and produces a geometric confinement effect under illumination.
[0014] In some possible implementations, the pore size of the nanopore structure is 30-100 nm, the center-to-center distance between adjacent pores is 1.5-3 times the pore size, and the porosity is 20%-50%; the groove width of the nanogroove structure is 20-80 nm, the center-to-center distance between adjacent grooves is 2-4 times the groove width, and the density of the nanogrooves is 20%-50%; the depth of the nanopore structure or nanogroove structure is 20%-50% of the thickness of the first gas-sensitive layer or the second gas-sensitive layer.
[0015] In some possible implementations, if the depth of the nanopore structure or nanogroove structure is too small, the specific surface area will be reduced, thereby reducing the gas adsorption sites and affecting the device sensitivity; if the depth of the nanopore structure or nanogroove structure is too large, the etching may penetrate the first gas-sensitive layer and damage the barrier layer or penetrate the second gas-sensitive layer and damage the gate.
[0016] In some possible implementations, if the aperture of the nanopore or the width of the nanogroove is too large, the geometric confinement capability of the nanostructure for incident light is reduced, the scattering and reflection efficiency of light within the nanopore or nanogroove is reduced, resulting in weakened light absorption and reduced generation efficiency of photogenerated carriers; while if the aperture of the nanopore or the width of the nanogroove is too small, the nanostructure cannot effectively achieve light diffraction and scattering, resulting in a shortened propagation path of light within the material, reduced generation efficiency of photogenerated carriers, and more difficult to precisely control during photolithography and etching, which may lead to structural inhomogeneity and increased surface roughness.
[0017] In some possible implementations, if the porosity of the nanopores or the density of the nanogrooves is too high, the structure of the first or second gas-sensitive layer may become loose, which will affect the stability of the device; if the porosity of the nanopores or the density of the nanogrooves is too low, the number of gas adsorption sites will be reduced, thereby affecting the sensitivity of the sensor.
[0018] In some possible implementations, an insertion layer is also included, which is located between the channel layer and the barrier layer. The insertion layer is made of one or more of the following materials: AlN, AlInN, and AlInGaN, etc. The interface between the insertion layer and the channel layer forms a 2DEG channel. At the same time, the insertion layer can raise the conduction band level at the interface, and significantly increase the concentration of 2DEG through the polarization effect.
[0019] In some possible implementations, the group III nitride device structure includes a planar structure, an interdigitated structure, a ring structure, a ring-interdigitated structure, or a complex semiconductor device structure having the above-mentioned group III nitride device structure features. The source, drain, and gate are all made of any one or more of nickel, gold, palladium, platinum, titanium, titanium nitride, and ITO. The gate includes a Schottky metal gate, a metal-insulator-semiconductor gate, a metal oxide semiconductor gate, a P-type nitride gate, or a complex gate structure having the above-mentioned gate structure features.
[0020] In some possible implementations, a gold halftone contact is formed between the source and drain and the barrier layer, and a gold halftone contact is formed between the gate and the barrier layer.
[0021] Secondly, a method for fabricating a group III nitride device with a periodically arranged nanostructure is provided, comprising:
[0022] Select the desired substrate and polish and clean the substrate;
[0023] A buffer layer, a channel layer, and a barrier layer are sequentially grown on the substrate according to a predetermined material, order, and thickness.
[0024] The source and drain regions are defined by photolithography on the barrier layer and source and drain metals are deposited. Combined with a rapid annealing process, gold-semiconductor contacts are formed between the source metal, the drain metal and the barrier layer.
[0025] On the barrier layer, the first gas-sensitive layer region is defined by photolithography between the source and the drain, and the first gas-sensitive layer is fabricated.
[0026] The first gas-sensitive layer is patterned using electron beam lithography and plasma etching to form a first gas-sensitive layer with a periodically arranged nanostructure, including:
[0027] An electron beam resist is spin-coated onto the surface of the first gas-sensitive layer, and a pattern mask is formed by electron beam exposure and development. The pattern includes:
[0028] Nanopore patterns: pore size 30-100 nm, center-to-center spacing between adjacent pores 1.5-3 times the pore size, porosity 20%-50%; or
[0029] Nanogroove pattern: Groove width is 20-80nm, the center-to-center distance between adjacent grooves is 2-4 times the groove width, and the density of nanogrooves is 20%-50%;
[0030] Plasma etching is used to transfer the pattern to the first gas-sensitive layer, with an etching depth of 20%-50% of the thickness of the first gas-sensitive layer;
[0031] Thirdly, a method for fabricating a group III nitride device having a periodically arranged nanostructure and including a gate is provided, comprising:
[0032] Select the desired substrate and polish and clean the substrate;
[0033] A buffer layer, a channel layer, and a barrier layer are sequentially grown on the substrate according to a predetermined material, order, and thickness.
[0034] The source and drain regions are defined by photolithography on the barrier layer and source and drain metals are deposited. Combined with a rapid annealing process, gold-semiconductor contacts are formed between the source metal, the drain metal and the barrier layer.
[0035] On the barrier layer, the gate region is defined by photolithography between the source and drain, and gate metal is deposited.
[0036] On the barrier layer, a first gas-sensitive layer region is defined by photolithography between the gate and the drain or between the gate and the source, and a first gas-sensitive layer is fabricated.
[0037] The first gas-sensitive layer is patterned using electron beam lithography and plasma etching to form a first gas-sensitive layer with a periodically arranged nanostructure, including:
[0038] An electron beam resist is spin-coated onto the surface of the first gas-sensitive layer, and a pattern mask is formed by electron beam exposure and development. The pattern includes:
[0039] Nanopore patterns: pore size 30-100 nm, center-to-center spacing between adjacent pores 1.5-3 times the pore size, porosity 20%-50%; or
[0040] Nanogroove pattern: Groove width is 20-80nm, the center-to-center distance between adjacent grooves is 2-4 times the groove width, and the density of nanogrooves is 20%-50%;
[0041] Plasma etching is used to transfer the pattern to the first gas-sensitive layer, with an etching depth of 20%-50% of the thickness of the first gas-sensitive layer;
[0042] Fourthly, a method for fabricating a group III nitride device having a periodically arranged nanostructure and including a gate, wherein a first gas-sensitive layer is located on a barrier layer and a second gas-sensitive layer is located on the gate, comprising:
[0043] Select the desired substrate and polish and clean the substrate;
[0044] A buffer layer, a channel layer, and a barrier layer are sequentially grown on the substrate according to a predetermined material, order, and thickness.
[0045] The source and drain regions are defined by photolithography on the barrier layer and source and drain metals are deposited. Combined with a rapid annealing process, gold-semiconductor contacts are formed between the source metal, the drain metal and the barrier layer.
[0046] On the barrier layer, the gate region is defined by photolithography between the source and drain, and gate metal is deposited.
[0047] On the barrier layer, a first gas-sensitive layer region is defined by photolithography between the gate and the drain or between the gate and the source, and a first gas-sensitive layer is prepared. On the gate, a second gas-sensitive layer region is defined by photolithography, and a second gas-sensitive layer is prepared.
[0048] The first and second gas-sensitive layers are patterned using electron beam lithography and plasma etching to form a first and second gas-sensitive layer with periodically arranged nanostructures, including:
[0049] Electron beam resist is spin-coated onto the surfaces of the first and second gas-sensitive layers, and a pattern mask is formed by electron beam exposure and development. The pattern includes:
[0050] Nanopore patterns: pore size 30-100 nm, center-to-center spacing between adjacent pores 1.5-3 times the pore size, porosity 20%-50%; or
[0051] Nanogroove pattern: Groove width is 20-80nm, the center-to-center distance between adjacent grooves is 2-4 times the groove width, and the density of nanogrooves is 20%-50%;
[0052] Plasma etching is used to transfer the pattern to the first gas-sensitive layer and the second gas-sensitive layer, respectively, with etching depths of 20%-50% of the thickness of the first gas-sensitive layer and the second gas-sensitive layer.
[0053] The target gas described in this invention refers to a combination of one or more gases capable of undergoing a redox reaction with the gas-sensitive layer of the device. The target gas includes, but is not limited to, any one or more combinations of H2, CO, NH3, H2S, and NO2. Reducing gases such as H2 are particularly suitable for the technical solution described in this invention.
[0054] This application has the following beneficial effects:
[0055] 1. The first and second gas-sensitive layers of the group III nitride device proposed in this application are etched to form a periodically arranged nanostructure, which can geometrically confine incident light. The sidewalls of the nanopores or nanogrooves enhance photon scattering, further prolonging the photon propagation path in the nanopores, increasing the interaction time between photons and the first and second gas-sensitive layers, significantly improving the generation efficiency of photogenerated carriers, and promoting the redox reaction of the target gas.
[0056] 2. The first and second gas-sensitive layers of the group III nitride device proposed in this application are highly sensitive to gas molecules and can generate a large number of active electron-hole pairs under illumination, thus making it easier to react with the target gas and significantly improving the reaction rate. When the target gas is adsorbed onto the surface of the first and second gas-sensitive layers, it will undergo a redox reaction with the electron-hole pairs on its surface, resulting in changes in the potential of the first and second gas-sensitive layers. The change in the potential of the first gas-sensitive layer will significantly modulate the concentration of 2DEG at the heterojunction interface of the channel layer and the barrier layer, while the second gas-sensitive layer directly modulates the work function of the gate metal through gas adsorption, causing a significant threshold voltage drift, which in turn causes a significant change in the device current, greatly improving the sensor sensitivity and significantly reducing the detection limit. Illumination assistance not only improves the sensor's sensitivity and response speed and reduces the detection limit, but also avoids the need for traditional high-temperature operating environments, thereby reducing power consumption and extending the device's lifespan. In addition, by controlling the materials of the first and second gas-sensitive layers, selective detection of specific gases can be achieved.
[0057] 3. The first and second gas-sensitive layers proposed in this application are etched to form a periodically arranged nanostructure, which has a higher specific surface area than conventional semiconductor devices, significantly increasing the adsorption sites of the target gas, thus enabling the group III nitride device to exhibit higher response value and sensitivity.
[0058] 4. The group III nitride device of this application uses group III nitride materials (such as GaN, AlGaN, InAlN, etc.) to fabricate the channel layer and barrier layer, forming a heterojunction structure such as AlGaN / GaN. This heterojunction structure generates a high concentration of 2DEG at the interface through spontaneous polarization and piezoelectric polarization effects. Thanks to the high carrier density of 2DEG, the group III nitride device designed in this application can respond highly to small changes in gas concentration in the environment, exhibiting extremely low detection limit (LOD), excellent sensitivity, and superior response performance. Attached Figure Description
[0059] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments of this application and their descriptions are used to explain this application and do not constitute an undue limitation of this application.
[0060] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0061] Figure 1 This is a three-dimensional structural schematic diagram of the group III nitride device of Embodiment 1 of this application;
[0062] Figure 2 This is a top view of the group III nitride device of Embodiment 1 of this application;
[0063] Figure 3 This is a cross-sectional structural schematic diagram of the group III nitride device of Embodiment 2 of this application;
[0064] Figure 4 This is a top view of the group III nitride device of Embodiment 2 of this application;
[0065] Figure 5 This is a cross-sectional structural schematic diagram of the group III nitride device of Embodiment 3 of this application;
[0066] Figure 6 This is a top view of the group III nitride device of Embodiment 3 of this application;
[0067] Figure 7 This is a schematic cross-sectional view of the group III nitride device of Embodiment 4 of this application;
[0068] Figure 8 This is a top view of the group III nitride device of Embodiment 4 of this application;
[0069] Figure 9This is a three-dimensional structural schematic diagram of the group III nitride device of Embodiment 5 of this application;
[0070] Figure 10 This is a cross-sectional structural schematic diagram of the group III nitride device of Embodiment 5 of this application;
[0071] Figure 11 This is a top view of the group III nitride device of Embodiment 5 of this application.
[0072] Figure label:
[0073] 1. Substrate; 2. Buffer layer; 3. Channel layer; 4. Barrier layer; 5. First gas-sensitive layer; 51. Nanopore; 52. Nanogroove; 6. Source; 7. Drain; 8. Gate; 9. Second gas-sensitive layer. Detailed Implementation
[0074] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0075] Example 1
[0076] This embodiment provides a group III nitride device with gas sensing function. The group III nitride device structure in this embodiment includes a planar structure, an interdigitated structure, a ring structure, a ring-interdigitated structure, or a complex semiconductor device structure with the above-mentioned group III nitride device structural features. This embodiment mainly introduces a group III nitride device with a planar structure.
[0077] Specifically, such as Figure 1 and Figure 2 As shown, the group III nitride device involved in Embodiment 1 of this application includes a substrate 1 and a buffer layer 2, a channel layer 3, a barrier layer 4 and a first gas-sensitive layer 5 sequentially formed on the substrate 1. A source electrode 6 and a drain electrode 7 are disposed on the barrier layer 4. The first gas-sensitive layer 5 is located between the source electrode 6 and the drain electrode 7. Both the source electrode 6 and the drain electrode 7 form a gold-semiconductor contact with the barrier layer 4. That is, the source electrode 6 forms a gold-semiconductor contact with the barrier layer 4, and the drain electrode 7 also forms a gold-semiconductor contact with the barrier layer 4. The source electrode 6 and the drain electrode 7 are made of any one or more of nickel, gold, palladium, platinum, titanium, titanium nitride and ITO. Of course, the source electrode 6 and the drain electrode 7 can also be made of other conductive metal materials.
[0078] In this embodiment, substrate 1 can be made of various substrate materials commonly used in semiconductor devices, such as silicon, sapphire, silicon carbide, gallium nitride, diamond, aluminum nitride, and QST. The materials of buffer layer 2, channel layer 3, and barrier layer 4 are selected from different materials among GaN, AlGaN, InGaN, InAlN, AlInGaN, and other group III nitrides, or at least one material containing different doping. The interface between channel layer 3 and barrier layer 4 forms a 2DEG channel.
[0079] In this embodiment, the first gas-sensitive layer 5 is made of a material sensitive to the target gas, and a periodic nanopore array structure 51 is formed through an etching process. Under light illumination, the first gas-sensitive layer 5 can generate a large number of active electron-hole pairs, which are used to catalyze the redox reaction of the target gas on its surface. Specifically, the first gas-sensitive layer 5 is made of one or more of the following materials: nitride materials, metal oxides, and two-dimensional transition metal dichalcogenides. Among them, the nitride materials are composed of any one or more of Group III nitride materials such as GaN, AlGaN, and InAlN; the metal oxides are composed of any one or more of metal oxide materials such as SnO2, ZnO, and TiO2; and the two-dimensional transition metal dichalcogenides are composed of any one or more of materials such as MoS2 and WS2.
[0080] In a further embodiment, the substrate thickness is 1-20 μm.
[0081] In a further embodiment, the thickness of the buffer layer is 1-10 μm.
[0082] In a further embodiment, the thickness of the channel layer is 100-500 nm.
[0083] In a further embodiment, the thickness of the barrier layer is 5-50 nm.
[0084] The following example uses silicon as the substrate material. The fabrication method of a group III nitride device designed in Example 1 includes:
[0085] S101. Select silicon as substrate 1, and polish and clean substrate 1.
[0086] S102. A buffer layer 2, a channel layer 3, and a barrier layer 4 are sequentially grown on substrate 1 using a metal-organic chemical vapor deposition (MOCVD) process, thereby forming a heterojunction epitaxial wafer on substrate 1. In this embodiment, GaN material is used as the buffer layer 2, with a thickness of 2-6 μm. GaN material is used as the channel layer 3, with a thickness of 200-350 nm. AlGaN material is used as the barrier layer 4, with a thickness of 10-30 nm, wherein the Al composition in the AlGaN material is 10-30%.
[0087] S103. The source and drain regions are determined by photolithography, and then the source and drain metals are deposited. In this embodiment, Ti / Al / Ni / Au (25nm / 125nm / 45nm / 100nm) is deposited as the source and drain metals by one or a combination of one or more of the following deposition methods: electron beam evaporation (E-beam), sputtering, atomic layer deposition (ALD), and plasma-enhanced atomic layer deposition (PEALD). The deposited metals are then annealed in a nitrogen atmosphere at a temperature of 820-890℃ for 20-60s to form ohmic contacts between the source metal, the drain metal, and the barrier layer 4.
[0088] S104. In this example, TiO2 material is used as the first gas-sensitive layer 5. The first gas-sensitive layer region is determined between the source electrode 6 and the drain electrode 7 by photolithography. A 50nm TiO2 thin film is deposited by combining one or more of the following deposition methods: Sputter, ALD, PEALD, etc.
[0089] S105. Electron beam resist is spin-coated onto the TiO2 surface and baked. Periodic nanopore patterns are defined by electron beam lithography and then developed. The pore size of nanopore 51 is 30-80nm, the spacing between pores is 1.5-2 times the pore size, and the porosity is 20%-30%. Subsequently, plasma etching is used to transfer the pattern to the TiO2 layer. The specific parameters are set as follows: ICP (Inductively Coupled Plasma Etching) power 150W, pressure 5mTorr, CF4 and Ar mixed gas is introduced, and the etching depth is 10-20nm. The residual resist is removed to form a periodic nanopore array structure.
[0090] The group III nitride device fabricated in this embodiment exhibits excellent CO sensing performance under illumination. Under illumination, the first gas-sensitive layer generates a large number of active electron-hole pairs. Furthermore, the periodic nanopore array structure of the first gas-sensitive layer provides geometric confinement for incident light. The sidewalls of the nanopores 51 enhance photon scattering and further extend the photon propagation path within the nanopores 51, increasing the interaction time between photons and the first gas-sensitive layer, thereby improving light absorption efficiency and increasing the concentration of photogenerated carriers. Simultaneously, the periodic nanopore array structure increases the gas adsorption sites of the first gas-sensitive layer, allowing CO to be fully adsorbed on its surface and undergo redox reactions with active electrons and holes, resulting in a change in the potential of the first gas-sensitive layer. This potential change causes a significant alteration in the 2DEG concentration at the AlGaN / GaN heterojunction interface, leading to a significant change in the device current and amplifying the detection signal. This cascade amplification effect of potential-2DEG-current not only significantly improves the device's sensitivity, but also allows even slight fluctuations in potential to trigger noticeable current changes, greatly reducing the detection limit. Furthermore, illumination lowers the activation energy required for CO adsorption onto the surface of the first gas-sensitive layer, reducing the potential barrier and making the adsorption process easier. The electrons and holes generated by illumination are also more active, facilitating electron exchange with CO, thus increasing the device's response speed by 20% compared to the unilluminated state.
[0091] Example 2
[0092] This embodiment provides a group III nitride device with gas sensing function. The group III nitride device structure in this embodiment includes a planar structure, an interdigitated structure, a ring structure, a ring-interdigitated structure, or a complex semiconductor device structure with the above-mentioned group III nitride device structural features. This embodiment mainly introduces a group III nitride device with a planar structure.
[0093] Specifically, such as Figure 3 and Figure 4 As shown in Embodiment 2 of this application, a group III nitride device includes a substrate 1 and a buffer layer 2, a channel layer 3, a barrier layer 4, and a first gas-sensitive layer 5 sequentially formed on the substrate 1. A source 6, a drain 7, and a gate 8 are disposed on the barrier layer 4. The first gas-sensitive layer 5 is located between the drain 7 and the gate 8. Gold-semiconductor contacts are formed between the source 6, the drain 7, and the gate 8 and the barrier layer 4. The source 6 and the drain 7 are made of any one or more of nickel, gold, palladium, platinum, titanium, titanium nitride, and ITO. Of course, the source 6 and the drain 7 can also be made of other conductive metal materials. The gate 8 includes a Schottky metal gate 8, a metal-insulating semiconductor gate 8, a metal-oxide-semiconductor gate 8, a P-type nitride gate 8, or a complex gate structure having the above-mentioned gate structure features.
[0094] In this embodiment, substrate 1 can be made of various substrate materials commonly used in semiconductor devices, such as silicon, sapphire, silicon carbide, gallium nitride, diamond, aluminum nitride, and QST. The materials of buffer layer 2, channel layer 3, and barrier layer 4 are selected from different materials among GaN, AlGaN, InGaN, InAlN, AlInGaN, and other group III nitrides, or at least one material containing different doping. The interface between channel layer 3 and barrier layer 4 forms a 2DEG channel.
[0095] In this embodiment, the first gas-sensitive layer 5 is made of a material sensitive to the target gas. The first gas-sensitive layer 5 is etched to form a periodic nanopore array structure. Under illumination, the first gas-sensitive layer 5 can generate a large number of active electron-hole pairs, which are used to catalyze the redox reaction of the target gas on its surface. Specifically, the first gas-sensitive layer 5 is made of one or more of the following materials: nitride materials, metal oxides, and two-dimensional transition metal dichalcogenides. Specifically, the nitride materials are composed of any one or more of Group III nitride materials such as GaN, AlGaN, and InAlN; the metal oxides are composed of any one or more of metal oxide materials such as SnO2, ZnO, and TiO2; and the two-dimensional transition metal dichalcogenides are composed of any one or more of materials such as MoS2 and WS2.
[0096] In a further embodiment, the substrate thickness is 1-20 μm.
[0097] In a further embodiment, the thickness of the buffer layer is 1-10 μm.
[0098] In a further embodiment, the thickness of the channel layer is 100-500 nm.
[0099] In a further embodiment, the thickness of the barrier layer is 5-50 nm.
[0100] The following example uses silicon as the substrate material. The fabrication method of a group III nitride device designed in Example 2 includes:
[0101] S101. Select silicon as substrate 1, and polish and clean substrate 1.
[0102] S102. A buffer layer 2, a channel layer 3, and a barrier layer 4 are sequentially grown on substrate 1 using an MOCVD process, thereby forming a heterojunction epitaxial wafer on substrate 1. In this embodiment, GaN material is used as the buffer layer 2, with a thickness of 2-4 μm. GaN material is used as the channel layer 3, with a thickness of 200-300 nm. AlGaN material is used as the barrier layer 4, with a thickness of 10-20 nm, wherein the Al composition in the AlGaN material is 10-30%.
[0103] S103. The source and drain regions are determined by photolithography, and then the source and drain metals are deposited. In this embodiment, Ti / Al / Ni / Au (25nm / 125nm / 45nm / 100nm) is deposited as the source and drain metals by combining one or more of the following deposition methods: E-beam, Sputter, ALD, PEALD, etc., and annealed at 820-890℃ for 20-60s in a nitrogen atmosphere to form ohmic contacts between the source metal, the drain metal, and the barrier layer 4.
[0104] S104. The gate region is determined by photolithography, wherein the gate region is located on the barrier layer 4 and between the source 6 and the drain 7, and then the gate metal is deposited. In this embodiment, Pt is deposited as the gate metal by one or more of the deposition methods such as E-beam, Sputter, ALD, and PEALD, with a thickness of 10-50 nm.
[0105] S105. In this example, ZnO material is used as the first gas-sensitive layer 5. The first gas-sensitive layer region is determined by photolithography between the drain 7 and the gate 8. A ZnO thin film with a thickness of 30nm is deposited by combining one or more of the following deposition methods: Sputter, ALD, PEALD, etc.
[0106] S106. Electron beam resist is spin-coated onto the ZnO thin film surface and baked. After defining a periodic nanopore pattern by electron beam lithography, it is developed. The pore size of nanopore 51 is 30-50nm, the spacing between pores is 1.5-2 times the pore size, and the porosity is 30%-50%. Subsequently, plasma etching is used to transfer the pattern to the ZnO layer. The specific parameters are set as follows: ICP power 500W, pressure 5mTorr, CH4, H2 and Ar mixed gas are introduced, the etching depth is 10-15nm, and the residual resist is removed to form a periodic nanopore array structure.
[0107] The group III nitride device fabricated in this embodiment exhibits excellent H2 sensing performance under illumination. Under illumination, the first gas-sensitive layer generates a large number of active electron-hole pairs. Furthermore, the periodic nanopore array structure of the first gas-sensitive layer provides geometric confinement for incident light. The sidewalls of the nanopores 51 enhance photon scattering and further extend the photon propagation path within the nanopores 51, increasing the interaction time between photons and the first gas-sensitive layer, thereby improving light absorption efficiency and increasing the concentration of photogenerated carriers. Simultaneously, the periodic nanopore array structure increases the gas adsorption sites of the first gas-sensitive layer, promoting the full adsorption of H2 on the surface of the first gas-sensitive layer and its redox reaction with active electrons and holes, leading to a change in the potential of the first gas-sensitive layer. This potential change causes a significant alteration in the 2DEG concentration at the AlGaN / GaN heterojunction interface, resulting in a significant change in the device current and amplifying the detection signal. This cascade amplification effect of potential-2DEG-current not only significantly improves the device's sensitivity, but also allows even slight fluctuations in potential to trigger noticeable current changes, greatly reducing the detection limit. Furthermore, illumination lowers the activation energy required for H2 adsorption onto the surface of the first gas-sensitive layer, reducing the potential barrier and making the adsorption process easier. The electrons and holes generated by illumination are also more active, facilitating electron exchange with H2, thus increasing the device's response speed by 30% compared to the unilluminated state.
[0108] Example 3
[0109] This embodiment provides a group III nitride device with gas sensing function. The group III nitride device structure in this embodiment includes a planar structure, an interdigitated structure, a ring structure, a ring-interdigitated structure, or a complex semiconductor device structure with the above-mentioned group III nitride device structural features. This embodiment mainly introduces a group III nitride device with a planar structure.
[0110] Specifically, such as Figure 5 and Figure 6 As shown, the group III nitride device involved in Embodiment 3 of this application includes a substrate 1 and a buffer layer 2, a channel layer 3, a barrier layer 4 and a first gas-sensitive layer 5 sequentially formed on the substrate 1. A source 6, a drain 7 and a gate 8 are disposed on the barrier layer 4. The first gas-sensitive layer 5 is located between the source 6 and the gate 8. A gold-semiconductor contact is formed between the source 6, the drain 7 and the gate 8 and the barrier layer 4. The source 6 and the drain 7 are made of any one or more of nickel, gold, palladium, platinum, titanium, titanium nitride and ITO. Of course, the source 6 and the drain 7 can also be made of other conductive metal materials. The gate 8 includes a Schottky metal gate 8, a metal-insulator semiconductor gate 8, a metal oxide semiconductor gate 8, a P-type nitride gate 8, or a complex gate structure with the above gate structure features.
[0111] In this embodiment, substrate 1 can be made of various substrate materials commonly used in semiconductor devices, such as silicon, sapphire, silicon carbide, gallium nitride, diamond, aluminum nitride, and QST. The materials of buffer layer 2, channel layer 3, and barrier layer 4 are selected from different materials among GaN, AlGaN, InGaN, InAlN, AlInGaN, and other group III nitrides, or at least one material containing different doping. The interface between channel layer 3 and barrier layer 4 forms a 2DEG channel.
[0112] In this embodiment, the first gas-sensitive layer 5 is made of a material sensitive to the target gas and is formed into a periodic nanopore array structure through an etching process. Under light illumination, the first gas-sensitive layer 5 can generate a large number of active electron-hole pairs, which are used to catalyze the redox reaction of the target gas on its surface. Specifically, the first gas-sensitive layer 5 is made of one or more of the following materials: nitride materials, metal oxides, and two-dimensional transition metal dichalcogenides. Among them, the nitride materials are composed of any one or more of Group III nitride materials such as GaN, AlGaN, and InAlN; the metal oxides are composed of any one or more of metal oxide materials such as SnO2, ZnO, and TiO2; and the two-dimensional transition metal dichalcogenides are composed of any one or more of materials such as MoS2 and WS2.
[0113] In a further embodiment, the substrate thickness is 1-20 μm.
[0114] In a further embodiment, the thickness of the buffer layer is 1-10 μm.
[0115] In a further embodiment, the thickness of the channel layer is 100-500 nm.
[0116] In a further embodiment, the thickness of the barrier layer is 5-50 nm.
[0117] The following example uses silicon as the substrate material. The fabrication method of a group III nitride device designed in this embodiment 3 includes:
[0118] S101. Select silicon as substrate 1, and polish and clean substrate 1.
[0119] S102. A buffer layer 2, a channel layer 3, and a barrier layer 4 are sequentially grown on substrate 1 using an MOCVD process, thereby forming a heterojunction epitaxial wafer on substrate 1. In this embodiment, GaN material is used as the buffer layer 2, with a thickness of 2-5 μm. GaN material is used as the channel layer 3, with a thickness of 150-300 nm. AlGaN material is used as the barrier layer 4, with a thickness of 15-30 nm, wherein the Al composition in the AlGaN material is 10-30%.
[0120] S103. The source and drain regions are determined by photolithography, and then the source and drain metals are deposited. In this embodiment, Ti / Al / Ni / Au (20nm / 130nm / 50nm / 150nm) is deposited as the source and drain metals by combining one or more of the following deposition methods: E-beam, Sputter, ALD, PEALD, etc., and annealed at 820-890℃ for 20-60s in a nitrogen atmosphere to form ohmic contacts between the source metal, the drain metal, and the barrier layer 4.
[0121] S104. The gate region is determined by photolithography, wherein the gate region is located on the barrier layer 4 and between the source 6 and the drain 7, and then the gate metal is deposited. In this embodiment, Pt is deposited as the gate metal by one or more of the deposition methods such as E-beam, Sputter, ALD, and PEALD, with a thickness of 10-80 nm.
[0122] S105. In this example, MoS2 material is used as the first gas-sensitive layer 5. The first gas-sensitive layer region is defined between the source 6 and the gate 8 by photolithography. A MoS2 thin film with a thickness of 10 nm is deposited by one or more of the following deposition methods: chemical vapor deposition (CVD), ALD, etc.
[0123] S106. Electron beam resist is spin-coated onto the MoS2 surface and baked. Periodic nanopore patterns are defined by electron beam lithography and then developed. The pore size of nanopore 51 is 40-60nm, the spacing between pores is 1.5-2 times the pore size, and the porosity is 30%-50%. Subsequently, the pattern is transferred to the MoS2 layer by plasma etching. The specific parameters are set as follows: ICP power 100W, pressure 10mTorr, SF6, CHF3 and Ar mixed gas are introduced, the etching depth is 2-5nm, and the residual resist is removed to form a periodic nanopore array structure.
[0124] The group III nitride device fabricated in this embodiment exhibits excellent NO2 sensing performance under illumination. Under illumination, the first gas-sensitive layer generates a large number of active electron-hole pairs. Furthermore, the periodic nanopore array structure of the first gas-sensitive layer provides geometric confinement for incident light. The sidewalls of the nanopores 51 enhance photon scattering and further extend the photon propagation path within the nanopores 51, increasing the interaction time between photons and the first gas-sensitive layer, thereby improving light absorption efficiency and increasing the concentration of photogenerated carriers. Simultaneously, the periodic nanopore array structure increases the gas adsorption sites of the first gas-sensitive layer, allowing NO2 to be fully adsorbed on its surface and undergo redox reactions with active electrons and holes, resulting in a change in the potential of the first gas-sensitive layer. This potential change causes a significant alteration in the 2DEG concentration at the AlGaN / GaN heterojunction interface, leading to a significant change in the device current and amplifying the detection signal. This cascade amplification effect of potential-2DEG-current not only significantly improves the device's sensitivity, but also allows even slight fluctuations in potential to trigger noticeable current changes, greatly reducing the detection limit. Furthermore, illumination lowers the activation energy required for NO2 adsorption onto the surface of the first gas-sensitive layer, reducing the potential barrier and making the adsorption process easier. The electrons and holes generated by illumination are also more active, facilitating electron exchange with NO2, thus increasing the device's response speed by 50% compared to the unilluminated state.
[0125] Example 4
[0126] This embodiment provides a group III nitride device with gas sensing function. The group III nitride device structure in this embodiment includes a planar structure, an interdigitated structure, a ring structure, a ring-interdigitated structure, or a complex semiconductor device structure with the above-mentioned group III nitride device structural features. This embodiment mainly introduces a group III nitride device with a planar structure.
[0127] Specifically, such as Figure 7 and Figure 8 As shown, the group III nitride device involved in Embodiment 4 of this application includes a substrate 1 and a buffer layer 2, a channel layer 3, a barrier layer 4 and a first gas-sensitive layer 5 sequentially formed on the substrate 1. A source 6, a drain 7 and a gate 8 are disposed on the barrier layer 4. The source 6, drain 7 and gate 8 are all gold-semiconductor contacts formed with the barrier layer 4. The source 6 and drain 7 are made of any one or more of nickel, gold, palladium, platinum, titanium, titanium nitride and ITO. Of course, the source 6 and drain 7 can also be made of other conductive metal materials.
[0128] In this embodiment, the first gas-sensitive layer 5 is disposed on the barrier layer 4 and located between the drain 7 and the gate 8. The second gas-sensitive layer 9 is disposed on the gate 8, covering the upper surface of the gate 8, and its boundary is located inside the sidewall of the gate 8 or substantially aligned with the sidewall of the gate 8, without extending to the barrier layer 4 outside the gate 8. The gate 8 includes a Schottky metal gate 8, a metal-insulator semiconductor gate 8, a metal oxide semiconductor gate 8, a P-type nitride gate 8, or a complex gate structure having the above-mentioned gate structure features.
[0129] In this embodiment, substrate 1 can be made of various substrate materials commonly used in semiconductor devices, such as silicon, sapphire, silicon carbide, gallium nitride, diamond, aluminum nitride, and QST. The materials of buffer layer 2, channel layer 3, and barrier layer 4 are selected from different materials among GaN, AlGaN, InGaN, InAlN, AlInGaN, and other group III nitrides, or at least one of these materials containing different dopants.
[0130] In this embodiment, both the first gas-sensitive layer 5 and the second gas-sensitive layer 9 are made of materials sensitive to the target gas. The first gas-sensitive layer 5 and the second gas-sensitive layer 9 are etched to form a periodic nanopore array structure, which can generate a large number of active electron-hole pairs under light illumination, catalyzing the redox reaction of the target gas on its surface. Specifically, the first gas-sensitive layer 5 and the second gas-sensitive layer 9 are made of one or more of the following materials: nitride materials, metal oxides, and two-dimensional transition metal dichalcogenides. Specifically, the nitride materials are composed of any one or more of Group III nitride materials such as GaN, AlGaN, and InAlN; the metal oxides are composed of any one or more of metal oxide materials such as SnO2, ZnO, and TiO2; and the two-dimensional transition metal dichalcogenides are composed of any one or more of materials such as MoS2 and WS2.
[0131] In a further embodiment, the substrate thickness is 1-20 μm.
[0132] In a further embodiment, the thickness of the buffer layer is 1-10 μm.
[0133] In a further embodiment, the thickness of the channel layer is 100-500 nm.
[0134] In a further embodiment, the thickness of the barrier layer is 5-50 nm.
[0135] The following example uses silicon as the substrate material. The fabrication method of a group III nitride device designed in Example 4 includes:
[0136] S101. Select silicon as substrate 1, and polish and clean substrate 1.
[0137] S102. A buffer layer 2, a channel layer 3, and a barrier layer 4 are sequentially grown on substrate 1 using an MOCVD process, thereby forming a heterojunction epitaxial wafer on substrate 1. In this embodiment, GaN material is used as the buffer layer 2, with a thickness of 2-3 μm. GaN material is used as the channel layer 3, with a thickness of 200-400 nm. AlGaN material is used as the barrier layer 4, with a thickness of 10-25 nm, wherein the Al composition in the AlGaN material is 10-30%.
[0138] S103. The source and drain regions are determined by photolithography, and then the source and drain metals are deposited. In this embodiment, Ti / Al / Ni / Au (20nm / 130nm / 50nm / 150nm) is deposited as the source and drain metals by combining one or more of the following deposition methods: E-beam, Sputter, ALD, PEALD, etc., and annealed at 820-890℃ for 20-60s in a nitrogen atmosphere to form ohmic contacts between the source metal, the drain metal, and the barrier layer 4.
[0139] S104. The gate region is determined by photolithography, wherein the gate region is located on the barrier layer 4 and between the source 6 and the drain 7, and then the gate metal is deposited. In this embodiment, Pt is deposited as the gate metal by one or more of the deposition methods such as E-beam, Sputter, ALD, and PEALD, with a thickness of 10-80 nm.
[0140] S105. In this example, SnO2 material is used as the first gas-sensitive layer 5 and the second gas-sensitive layer 9. The first gas-sensitive layer region and the second gas-sensitive layer region are defined on the barrier layer 4 and the gate 8 respectively by photolithography. A SnO2 thin film with a thickness of 40nm is deposited on the barrier layer 4 and the gate 8 by one or more of the deposition methods such as Sputter, ALD, and PEALD.
[0141] S106. Electron beam resist is spin-coated onto the SnO2 thin film surface and baked. Periodic nanopore patterns are defined by electron beam lithography and then developed. The pore diameter of nanopore 51 is 30-60 nm, the spacing between pores is 1.5-2 times the pore diameter, and the porosity is 20%-40%. Subsequently, the pattern is transferred to the SnO2 layer by plasma etching. The specific parameters are set as follows: ICP power 100W, pressure 5mTorr, CF4 and Ar mixed gas is introduced, and the etching depth is 10-20 nm. The residual resist is removed, and the nanopore array is completed.
[0142] The group III nitride device fabricated in this embodiment exhibits excellent H2 sensing performance under illumination. Under illumination, the first and second gas-sensitive layers generate a large number of active electron-hole pairs. Furthermore, the periodic nanopore array structure provides geometric confinement for incident light. The sidewalls of the nanopores enhance photon scattering and further extend the photon propagation path within the nanopores, increasing the interaction time between photons and the first and second gas-sensitive layers, thereby improving light absorption efficiency and increasing the concentration of photogenerated carriers. Simultaneously, the periodic nanopore array structure increases the gas adsorption sites of the first and second gas-sensitive layers, allowing H2 to be fully adsorbed on their surfaces and undergo redox reactions with active electrons and holes. The second gas-sensitive layer directly modulates the work function of the gate metal through gas adsorption, inducing a significant threshold voltage drift. Meanwhile, the first gas-sensitive layer efficiently modulates the transport characteristics of the two-dimensional electron gas in the channel through its carried charge, thereby greatly improving the device's response amplitude and detection sensitivity. Furthermore, illumination lowers the activation energy required for H2 adsorption onto the surfaces of the first and second gas-sensitive layers, reducing the potential barrier and making the adsorption process easier. The electrons and holes generated by illumination are also more active, facilitating electron exchange with H2 and increasing the device's response speed. The group III nitride device fabricated in this embodiment does not require a high-temperature environment, reducing the power consumption needed to maintain high temperatures and extending the device's lifespan.
[0143] Example 5
[0144] This embodiment provides a group III nitride device with gas sensing function. The group III nitride device structure in this embodiment includes a planar structure, an interdigitated structure, a ring structure, a ring-interdigitated structure, or a complex semiconductor device structure with the above-mentioned group III nitride device structural features. This embodiment mainly introduces a group III nitride device with a planar structure.
[0145] Specifically, such as Figure 9 , Figure 10 and Figure 11 As shown in Embodiment 5 of this application, a group III nitride device includes a substrate 1 and a buffer layer 2, a channel layer 3, a barrier layer 4, and a first gas-sensitive layer 5 sequentially formed on the substrate 1. A source electrode 6 and a drain electrode 7 are disposed on the barrier layer 4. The first gas-sensitive layer 5 is located between the source electrode 6 and the drain electrode 7. Both the source electrode 6 and the drain electrode 7 form gold-semiconductor contacts with the barrier layer 4. That is, the source electrode 6 forms a gold-semiconductor contact with the barrier layer 4, and the drain electrode 7 also forms a gold-semiconductor contact with the barrier layer 4. The source electrode 6 and the drain electrode 7 are made of any one or more of nickel, gold, palladium, platinum, titanium, titanium nitride, and ITO. Of course, the source electrode 6 and the drain electrode 7 can also be made of other conductive metal materials.
[0146] In this embodiment, substrate 1 can be made of various substrate materials commonly used in semiconductor devices, such as silicon, sapphire, silicon carbide, gallium nitride, diamond, aluminum nitride, and QST. The materials of buffer layer 2, channel layer 3, and barrier layer 4 are selected from different materials among GaN, AlGaN, InGaN, InAlN, AlInGaN, and other group III nitrides, or at least one material containing different doping. The interface between channel layer 3 and barrier layer 4 forms a 2DEG channel.
[0147] In this embodiment, the first gas-sensitive layer 5 is made of a material sensitive to the target gas and is formed into a periodic nanogroove array structure through an etching process. Under light illumination, the first gas-sensitive layer 5 can generate a large number of active electron-hole pairs, which are used to catalyze the redox reaction of the target gas on its surface. Specifically, the first gas-sensitive layer 5 is made of one or more of the following materials: nitride materials, metal oxides, and two-dimensional transition metal dichalcogenides. Among them, the nitride materials are composed of any one or more of Group III nitride materials such as GaN, AlGaN, and InAlN; the metal oxides are composed of any one or more of metal oxide materials such as SnO2, ZnO, and TiO2; and the two-dimensional transition metal dichalcogenides are composed of any one or more of materials such as MoS2 and WS2.
[0148] In a further embodiment, the substrate thickness is 1-20 μm.
[0149] In a further embodiment, the thickness of the buffer layer is 1-10 μm.
[0150] In a further embodiment, the thickness of the channel layer is 100-500 nm.
[0151] In a further embodiment, the thickness of the barrier layer is 5-50 nm.
[0152] The following example uses silicon as the substrate material. The fabrication method of a group III nitride device designed in Example 5 includes:
[0153] S101. Select silicon as substrate 1, and polish and clean substrate 1.
[0154] S102. A buffer layer 2, a channel layer 3, and a barrier layer 4 are sequentially grown on substrate 1 using an MOCVD process, thereby forming a heterojunction epitaxial wafer on substrate 1. In this embodiment, GaN material is used as the buffer layer 2, with a thickness of 2-5 μm. GaN material is used as the channel layer 3, with a thickness of 250-400 nm. AlGaN material is used as the barrier layer 4, with a thickness of 10-35 nm, wherein the Al composition in the AlGaN material is 10-30%.
[0155] S103. The source and drain regions are determined by photolithography, and then the source and drain metals are deposited. In this embodiment, Ti / Al / Ni / Au (25nm / 125nm / 45nm / 100nm) is deposited as the source and drain metals by combining one or more of the following deposition methods: E-beam, Sputter, ALD, PEALD, etc., and then annealed at 820-890℃ for 20-60s in a nitrogen atmosphere to form ohmic contacts between the source metal, the drain metal, and the barrier layer 4.
[0156] S104. In this example, GaN material is used as the first gas-sensitive layer 5. The first gas-sensitive layer region is determined between the source electrode 6 and the drain electrode 7 by photolithography. A GaN thin film with a thickness of 50 nm is deposited by combining one or more of the following deposition methods: Sputter, ALD, PEALD, etc.
[0157] S105. Spin-coat an electron beam resist onto the GaN surface and bake. Define a periodic nanogroove pattern by electron beam lithography and then develop it. The width of the nanogroove 52 is 20-60 nm, the depth is 10-25 nm, the center-to-center spacing of adjacent nanogrooves 52 is 2-3 times the width of the nanogroove, and the density of the nanogrooves 52 is 30%-40%. Then, use a plasma etching process to transfer the pattern to the GaN thin film. The specific parameters are set as follows: ICP power 100 W, pressure 5 mTorr, and a mixed gas of Cl2, BCl3 and Ar is introduced to remove residual resist, thus completing the fabrication of the nanogroove array.
[0158] The group III nitride device fabricated in this embodiment exhibits excellent sensing performance for NH3 under illumination. Under illumination, the first gas-sensitive layer generates a large number of active electron-hole pairs. Furthermore, the periodic nanogroove array structure of the first gas-sensitive layer provides geometric confinement for incident light. The sidewalls of the nanogroove 52 enhance photon scattering and further extend the photon propagation path within the nanogroove 52, increasing the interaction time between the photons and the first gas-sensitive layer, thereby improving light absorption efficiency and increasing the concentration of photogenerated carriers. Simultaneously, the periodic nanogroove array structure increases the gas adsorption sites of the first gas-sensitive layer, allowing NH3 to be fully adsorbed on the surface of the first gas-sensitive layer and undergo redox reactions with active electrons and holes, resulting in a change in the potential of the first gas-sensitive layer. This potential change causes a significant alteration in the 2DEG concentration at the AlGaN / GaN heterojunction interface, leading to a significant change in the device current and amplifying the detection signal. This cascade amplification effect of potential-2DEG-current not only significantly improves the device's sensitivity, but also allows even slight fluctuations in potential to trigger noticeable current changes, greatly reducing the detection limit. Furthermore, illumination lowers the activation energy required for NH3 adsorption onto the surface of the first gas-sensitive layer, reducing the potential barrier and making the adsorption process easier. Additionally, the electrons and holes generated by illumination are more active, facilitating electron exchange with NH3 and increasing the device's response speed.
[0159] The above are merely preferred embodiments of this application; however, the scope of protection of this application is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in this application, based on the technical solution and its improved concept, should be covered within the scope of protection of this application.
Claims
1. A group III nitride device, characterized in that, From bottom to top, it includes substrate, buffer layer, channel layer, barrier layer and first gas sensitive layer, the source and the drain are arranged on the barrier layer, the first gas sensitive layer is arranged between the source and the drain of the device, the first gas sensitive layer is composed of a material sensitive to target gas, the first gas sensitive layer has a periodic nanostructure, the periodic nanostructure includes nano-hole structure and / or nano-groove structure, the nano-hole structure forms a hole structure along the direction perpendicular to the surface of the first gas sensitive layer, and the nano-groove structure forms a strip structure along the direction parallel to the surface of the first gas sensitive layer; the periodic nanostructure is used to increase the gas adsorption area and produce geometric confinement effect under light; the III-nitride device realizes the detection of target gas through the synergistic amplification of the first gas sensitive layer with periodic nanostructure and the 2DEG at the channel.
2. The group III nitride device of claim 1, wherein The III-nitride device further includes a gate electrode, the gate electrode is arranged on the barrier layer and between the source and the drain, and the first gas sensitive layer is arranged between the source and the gate electrode or between the gate electrode and the drain.
3. The group III nitride device of claim 2, wherein, The upper surface of the gate electrode is further provided with a second gas sensitive layer, the second gas sensitive layer is composed of a material sensitive to target gas, the second gas sensitive layer has a periodic nanostructure, the nano-hole structure forms a hole structure along the direction perpendicular to the surface of the second gas sensitive layer, and the nano-groove structure forms a strip structure along the direction parallel to the surface of the second gas sensitive layer, the second gas sensitive layer covers the upper surface of the gate electrode, and the boundary thereof is located within the sidewall of the gate electrode or substantially aligns with the sidewall of the gate electrode without extending onto the barrier layer outside the gate electrode.
4. The group III nitride device of any of claims 1-3, wherein the device is a light emitting diode. The substrate is made of one or more of the following materials: silicon, sapphire, silicon carbide, gallium nitride, diamond, aluminum nitride and QST; And / or The materials of the buffer layer, the channel layer and the barrier layer are respectively selected from different materials in GaN, AlGaN, InGaN, InAlN, AlInGaN and other III-nitride materials, or at least one of the materials is selected to contain different doping, wherein the interface of the channel layer and the barrier layer forms a 2DEG channel; And / or The first gas sensitive layer and the second gas sensitive layer are both composed of one or more of the following materials: nitride material including gallium nitride, aluminum gallium nitride or indium aluminum nitride; metal oxide including tin dioxide, zinc oxide or titanium dioxide; and two-dimensional transition metal dichalcogenide including molybdenum disulfide or tungsten disulfide.
5. The group III nitride device of any of claims 1-3, wherein the device is a light emitting diode. The periodic nanostructure includes nano-hole structure and / or nano-groove structure, the shape of the etching section of the nano-hole structure in the direction parallel to the surface of the first gas sensitive layer or the second gas sensitive layer is circular, elliptical or polygonal; the shape of the etching section of the nano-groove structure in the direction parallel to the surface of the first gas sensitive layer or the second gas sensitive layer is rectangular, trapezoidal or V-shaped; the periodic nanostructure has a periodic arrangement feature, forms an array-like distribution, and produces geometric confinement effect under light.
6. The group III nitride device of any of claims 1-3, wherein the device is a light emitting diode. The pore diameter of the nano-pore structure is 30-100 nm, the distance between adjacent pore centers is 1.5-3 times of the pore diameter, and the porosity is 20%-50%; the groove width of the nano-groove structure is 20-80 nm, the distance between adjacent groove centers is 2-4 times of the groove width, and the density of the nano-groove is 20%-50%; the depth of the nano-pore structure or the nano-groove structure is 20%-50% of the thickness of the first gas-sensitive layer or the second gas-sensitive layer.
7. The group III nitride device of any of claims 1-3, wherein, The III-nitride device structure includes a planar structure, an interdigital structure, a ring structure, a ring interdigital structure, or a complex semiconductor device structure having the features of the above III-nitride device structure, the source, the drain and the gate are made of any one or more of nickel, gold, palladium, platinum, titanium, titanium nitride and ITO, the gate includes a Schottky metal gate, a metal-insulator-semiconductor gate, a metal-oxide-semiconductor gate, a P-type nitride gate, or a complex gate structure having the features of the above gate structure, wherein the source and the drain form a gold-semiconductor contact with the barrier layer, and the gate forms a gold-semiconductor contact with the barrier layer.
8. A method of fabricating a group III nitride device, comprising: The preparation method for preparing the III-nitride device with periodic nano-structures as claimed in claim 1 comprises the following steps: selecting a desired substrate and polishing and cleaning the substrate; growing a buffer layer, a channel layer and a barrier layer on the substrate in a predetermined material, order and thickness; determining the source and drain regions on the barrier layer by photolithography and depositing source and drain metals, and combining a rapid annealing process to form a gold-semiconductor contact between the source and drain metals and the barrier layer; determining the first gas-sensitive layer region between the source and drain on the barrier layer by photolithography and preparing the first gas-sensitive layer; patterning the first gas-sensitive layer by electron beam lithography and plasma etching to form the first gas-sensitive layer with periodic nano-structures.
9. A method of fabricating a group III nitride device, comprising: The preparation method for preparing the III-nitride device with periodic nano-structures and including a gate as claimed in claim 2 comprises the following steps: selecting a desired substrate and polishing and cleaning the substrate; growing a buffer layer, a channel layer and a barrier layer on the substrate in a predetermined material, order and thickness; determining the source and drain regions on the barrier layer by photolithography and depositing source and drain metals, and combining a rapid annealing process to form a gold-semiconductor contact between the source and drain metals and the barrier layer; determining the gate region on the barrier layer by photolithography and depositing gate metal between the source and drain or between the source and gate; determining the first gas-sensitive layer region on the barrier layer by photolithography and preparing the first gas-sensitive layer between the source and drain or between the source and gate; patterning the first gas-sensitive layer by electron beam lithography and plasma etching to form the first gas-sensitive layer with periodic nano-structures.
10. A method of fabricating a group III nitride device, comprising: The preparation method for preparing the III-nitride device with periodic nano-structures and including a gate as claimed in claim 3 comprises the following steps: Selecting a desired substrate and polishing and cleaning the substrate; Growth of a buffer layer, a channel layer and a barrier layer on the substrate in a predetermined material, order and thickness; Defining source and drain regions on the barrier layer by photolithography and depositing source and drain metals, forming ohmic contacts between the source and drain metals and the barrier layer by a rapid annealing process; Defining a gate region between the source and drain on the barrier layer by photolithography and depositing a gate metal; Defining a first gas sensitive layer region between the gate and the drain or between the gate and the source on the barrier layer by photolithography and preparing a first gas sensitive layer, and defining a second gas sensitive layer region on the gate by photolithography and preparing a second gas sensitive layer; Patterning the first and second gas sensitive layers by electron beam lithography and plasma etching to form the first and second gas sensitive layers with periodically arranged nanostructures.