An AlGaN / GaN thin film sensor with enhanced sensitivity and capable of monitoring ultraviolet and pressure simultaneously

Abstract

The application discloses an AlGaN / GaN thin film sensor with enhanced sensitivity and capable of monitoring ultraviolet and pressure, which comprises an AlGaN / GaN-based thin film deposited on the upper surface of a silicon substrate, and a square groove is formed on the lower surface of the silicon substrate; a square thin film area of the sensor is formed on the thin film at a position corresponding to the square groove; a HEMT transistor is arranged at the center of each side of the square thin film area; and the outer edge of the transistor exceeds the square thin film area by 50-100 mu m. The four gate high electron mobility transistors are arranged at the center positions of the four sides of the square thin film, the influence of the 2DEG concentration change caused by the gravity of the thin film is reduced, the output current is increased without additional air pressure, the sensitivity of the pressure sensor is improved, and the AlGaN / GaN thin film sensor integrating the high-sensitivity pressure sensor and the ultraviolet detector is prepared.

Description

Technical Field

[0001] This patent belongs to the field of sensors, specifically relating to an AlGaN / GaN thin-film sensor with enhanced sensitivity that enables simultaneous monitoring of ultraviolet light and pressure, and its fabrication method. Background Technology

[0002] With the rapid development of IoT technology, intelligent sensing devices are gradually evolving towards multi-functional integration, miniaturization, and low power consumption. The IoT connects the physical and digital worlds, relying on various sensors as its "nerve endings" to collect and process environmental data in real time. Sensor technology has become a crucial component of the IoT's core infrastructure, and its performance directly determines the sensing accuracy and response speed of the IoT system.

[0003] In complex scenarios such as industrial monitoring and aerospace, the need for simultaneous monitoring of pressure and ultraviolet radiation is becoming increasingly prominent. Traditional silicon-based pressure sensors suffer from limited sensitivity due to their low electron mobility; however, AlGaN / GaN heterojunctions, with their interfacial two-dimensional electron gas (2DEG) piezoelectric properties, have become an ideal choice for high-performance pressure sensing: pressure-induced thin-film deformation can significantly modulate the 2DEG concentration through piezoelectric polarization, achieving high-sensitivity signal conversion. Simultaneously, the wide bandgap of AlGaN materials (covering the ultraviolet band) makes it naturally suited for ultraviolet detection; devices built upon it can respond to ultraviolet light through photoconductivity.

[0004] However, existing technologies have obvious limitations: pressure sensors mostly adopt local area charge collection mode, which can only utilize the 2DEG changes in a specific area, while the polarization enhancement effect caused by the global thin film deformation due to pressure is not fully converted into an electrical signal, resulting in limited sensitivity and dynamic range; moreover, the integration of pressure and ultraviolet detection functions is poor, and discrete devices or simple integration schemes are not only complex, but also prone to signal cross-interference, failing to utilize the common control mechanism of 2DEG to achieve synergistic optimization.

[0005] Therefore, developing an integrated sensor that can efficiently collect charge changes in multiple regions and combines high-sensitivity pressure sensing with excellent ultraviolet detection performance has become a key direction to overcome the limitations of existing technologies. Summary of the Invention

[0006] To address the aforementioned problems, this invention first provides an AlGaN / GaN thin-film sensor with enhanced sensitivity, enabling simultaneous monitoring of ultraviolet light and pressure. By placing four gated high electron mobility transistors (HEMTs) at the center of each of the four sides of a square AlGaN / GaN thin film, the influence of 2DEG concentration changes caused by the film's own gravity is reduced, resulting in increased output current without external pressure and improved pressure sensor sensitivity. Simultaneously, by changing the material and thickness of the gate electrode, the device's response to ultraviolet light is increased, thus fabricating an AlGaN / GaN thin-film sensor integrating a high-sensitivity pressure sensor and an ultraviolet detector.

[0007] To achieve the above objectives, the present invention first provides an AlGaN / GaN thin-film sensor with enhanced sensitivity, enabling simultaneous monitoring of ultraviolet light and pressure. The sensor includes an AlGaN / GaN-based thin film deposited on the upper surface of a silicon substrate. A square groove is formed on the lower surface of the silicon substrate. The position on the AlGaN / GaN-based thin film corresponding to the square groove is the square thin-film region of the sensor. HEMT transistors are respectively disposed at the center of the four sides of the square thin-film region. The source or drain of two adjacent HEMT transistors is connected by a metal connection line and connected to a second source or drain. The second source or drain is located at the four vertices of the AlGaN / GaN square thin film. Two second sources are diagonally positioned and connected to a common source via a second metal connection line. Two second drains are diagonally positioned and connected to a common drain via a third metal connection line. The gate metals of two opposing HEMT transistors are connected by a second gate metal connection and connected to a common gate. A sealed cavity is formed between the square groove and the silicon wafer.

[0008] In one embodiment of the present invention, the outer edge of the HEMT transistor extends 50–100 μm beyond the square thin film region, and the area of ​​the square thin film region is (500–700) * (500–700) μm. 2 .

[0009] In one embodiment of the present invention, the AlGaN / GaN-based thin film includes a buffer layer, a GaN channel layer, an AlN insertion layer, an AlGaN barrier layer, and a GaN capping layer sequentially deposited on a silicon substrate, and the AlGaN / GaN-based thin film is etched to form four HEMT transistors.

[0010] In one embodiment of the present invention, the size of the HEMT transistor is 200*200~400*400um. 2 The AlGaN / GaN-based thin film is etched from the top down to the GaN channel layer, and the etching depth of the GaN channel layer accounts for 50 to 100% of the total thickness of the GaN channel layer.

[0011] In one embodiment of the present invention, the thickness of the AlGaN / GaN-based thin film is 3 to 5 μm, wherein the thickness of the GaN channel layer is 0.3 to 0.4 μm.

[0012] In one embodiment of the present invention, the stacked structure of the materials of the first source electrode, the first drain electrode, the second source electrode, the second drain electrode, the first metal connection line, and the second gate metal is Ti / Al / Ni / Au, with thicknesses of 20 / 160 / 55 / 45nm respectively.

[0013] In one embodiment of the present invention, the dimensions of the source electrode II and the drain electrode II are (50~100)*(50~100)um. 2 .

[0014] In one embodiment of the present invention, the material stacking structure of the gate metal is Ni / Au, with a thickness of 5nm / 5nm and a width of 50-100nm.

[0015] In one embodiment of the present invention, the linewidths of the second and third metal interconnects are 20µm to 50µm, and the materials used are Ti / Au, Ni / Au, or Ti / Al / Ni / Au, with thicknesses of 10–30 / 20–60nm, 20–30 / 40–60nm, or 20 / 100 / 25 / 20nm. When using Ti / Au or Ni / Au, it is optimal that the thickness of Au is twice that of Ti or Ni.

[0016] In one embodiment of the present invention, the dimensions of the total source, total gate, and total drain are (200-350)*(200-350)um. 2 The material used is Ni / Au, with a thickness of 50-100 / 100-200 nm.

[0017] This invention also discloses a method for fabricating an AlGaN / GaN thin-film sensor with enhanced sensitivity, enabling simultaneous monitoring of ultraviolet light and pressure, comprising the following steps:

[0018] (1) A buffer layer, a GaN channel layer, an AlN insertion layer, an AlGaN barrier layer, and a GaN capping layer are sequentially formed on the upper surface of a silicon substrate to obtain an AlGaN / GaN-based thin film.

[0019] (2) Etch the AlGaN / GaN-based thin film obtained in step (1) from the top until the GaN channel layer is etched to a certain depth to isolate the two-dimensional electron gas between devices and form four HEMT transistors on the AlGaN / GaN-based thin film.

[0020] (3) The GaN capping layer of the HEMT transistor obtained in step (2) is etched to etch out the positions of the first source, the first drain and the first metal connection line of the HEMT. The upper surface of the AlGaN barrier layer is exposed at the positions of the first source, the first drain and the first metal connection line. Metal is sputtered on the GaN capping layer and the AlGaN barrier layer to form ohmic contacts. The first source, the first drain, the second source, the second drain, the first metal connection line and the second gate metal are formed by annealing.

[0021] (4) Sputter metal Ni / Au onto the GaN capping layer of the structure obtained in step (3) to form gate metal 1;

[0022] (5) Sputter metal Ni / Au onto the structure obtained in step (4) as the final test connection port source, gate and drain;

[0023] (6) A first silicon nitride insulating layer is deposited on the surface of the structure formed in step (5), and a photolithographic pattern is used to etch out the source two, drain two, total source, total drain and total gate portions;

[0024] (7) In step (6), the lead wire between the source electrode and the source electrode is photolithographically formed on the surface of the first silicon nitride insulating layer, and Ni / Au metal is deposited at 20 / 40nm.

[0025] (8) Continue to deposit a second silicon nitride insulating layer on top of step (7), and etch out the drain, source, drain and gate portions of the photolithography pattern;

[0026] (9) Photolithographically etch the lead between the drain electrodes on the surface of the second silicon nitride insulating layer obtained in step (8), and deposit Ni / Au metal at 20 / 40nm as the metal connection line three;

[0027] (10) Continue to deposit a third silicon nitride insulating layer on the structure of step (9), and etch out the total source, total drain and total gate portions of the photolithography pattern;

[0028] (11) Photolithographic pattern on the lower surface of the silicon substrate of the structure obtained in step (10) is used to etch and expose the lower surface of the buffer layer to form an opening;

[0029] (12) The silicon substrate with the structure obtained in step (11) is bonded to a standard silicon wafer using Au-Au bonding, so that the opening in step (11) forms a closed cavity with the silicon wafer.

[0030] In one embodiment of the present invention, the thicknesses of the first silicon nitride insulating layer, the second silicon nitride insulating layer, and the third silicon nitride insulating layer are all 10 to 30 nm.

[0031] The present invention also discloses an application of the above-mentioned AlGaN / GaN thin film sensor in industrial detection and aerospace fields.

[0032] Beneficial effects:

[0033] (1) The AlGaN / GaN heterojunction enhances the piezoelectric polarization effect with increasing stress, causing changes in 2DEG concentration. COMSOL simulations show that when external pressure is uniformly applied downwards from above the film, the stress is at its maximum at the center of the fixed side of the square film. This invention fabricates four gate high electron mobility transistors (HEMTs) and places them at the center of the four sides of the square film to collect the changes in 2DEG concentration at the stress maximum under different pressures. Compared with placing the HEMT devices at the center of the film, placing them at the center of the four sides of the square film reduces the influence of 2DEG concentration changes caused by the film's own gravity, thus increasing the sensor's output current without external pressure, thereby increasing the sensor's sensitivity. At the same time, due to the photoconductive effect, this device also has a good response to ultraviolet light, and multiple collection points of charge changes enhance the current output signal, giving the device excellent ultraviolet detection performance.

[0034] (2) This invention finds the operating voltage at which the device is most sensitive to air pressure through testing under different gate control conditions, thereby maximizing the device’s response to air pressure; in the fabrication process, the gate electrode is thinned to Ni / Au (5nm / 5nm) and the gate length is made to within 50nm, which can enhance the effect of ultraviolet light penetrating into AlGaN and increase the photocurrent, thereby enhancing the device’s response to ultraviolet light.

[0035] (3) Compared with traditional devices, this invention adopts a multi-region current collection method, sets the HEMT placement area to the center of the thin film edge, and uses grid control adjustment to maximize the device's sensitivity to air pressure response, greatly improving the sensitivity of the pressure sensor and the responsivity and detectivity of ultraviolet light response. The pressure sensor prepared by this invention can achieve a sensitivity of up to 11.45% / kPa at a working voltage of Vgs = -3V and Vds = 3.0V. As an ultraviolet detector, its responsivity and detectivity are as high as 326806.7593A / W and 5.64E+13Jones, respectively, which are far higher than the existing technology level. Attached Figure Description

[0036] Figure 1 This is an overview structural diagram and a partial dimensional schematic diagram of Embodiment 1 of the present invention, wherein 201-source one, 202-drain one, 203-gate metal one, 204-metal connection line one, 205-gate metal two, 301-source two, 302-drain two, 303-metal connection line two, 304-metal connection line four, 401-total source, 402-total drain, and 403-total gate.

[0037] Figure 2This is a cross-sectional structural diagram of the device in Embodiment 1 of the present invention, corresponding to... Figure 1 The cross-sectional view at the dashed line position is shown in the figure, where 100-wafer; 101-silicon substrate; 102-buffer layer; 103-GaN channel layer; 104-AlN embedding layer; 105-AlGaN barrier; 106-GaN capping layer; 110-Au-Au bonding layer.

[0038] Figure 3 This is a HEMT structure diagram and its dimensions on an active region of the device of Embodiment 1 of the present invention.

[0039] Figure 4 This is a top-down view of the manufacturing process flow diagram of the device of the present invention.

[0040] Figure 5 This is a process flow diagram of the device of the present invention. Figure 1 Taking the fabrication of a HEMT transistor in a square region as an example, excluding the fabrication of source / drain diodes, gate metal diodes, total source / drain gate and metal interconnects, the following components are defined: 100 - wafer; 101 - silicon substrate; 102 - buffer layer; 103 - GaN channel layer; 104 - AlN embedding layer; 105 - AlGaN barrier; 106 - GaN capping layer; 107 - Ti / Al / Ni / Au layer; 108 - Ni / Au layer; 109 - silicon nitride layer; 110 - Au-Au bonding layer.

[0041] Figure 6 These are the transfer curve and leakage current curve of the device of the present invention.

[0042] Figure 7 The output curve of the device in Embodiment 1 of the present invention at Vgs = -3V and Vds = 3.0V, and the sensitivity curve obtained by fitting the relationship between the relative current change and the air pressure.

[0043] Figure 8 This is a graph showing the ultraviolet detection performance of the device in Embodiment 1 of the present invention.

[0044] Figure 9 These are the pressure sensitivity diagram and ultraviolet detection performance diagram of the device in Embodiment 2 of the present invention.

[0045] Figure 10 The output curve of the device in Comparative Example 1 of this invention at Vgs = -3V and Vds = 3.0V, and the sensitivity curve obtained by fitting the relationship between the relative current change and the air pressure.

[0046] Figure 11 This is a graph showing the ultraviolet detection performance of the device in Comparative Example 1 of this invention. Detailed Implementation

[0047] In the following description, for illustrative purposes and not for limiting purposes, those skilled in the art should understand that the present invention can also be implemented in other embodiments without these specific details. To illustrate the technical solutions described in the present invention, specific embodiments are described below.

[0048] Example 1

[0049] A method for fabricating an AlGaN / GaN thin-film sensor with enhanced sensitivity, enabling simultaneous monitoring of ultraviolet light and pressure, includes the following steps:

[0050] (1) A 4µm buffer layer 102, a 300nm GaN channel layer 103, a 1nm AlN insertion layer 104, a 20nm AlGaN barrier layer 105, and a 2nm GaN capping layer 106 are sequentially formed on the upper surface of a silicon substrate 101 to obtain an AlGaN / GaN-based thin film.

[0051] (2) The AlGaN / GaN-based thin film obtained in step (1) is etched from the top. The thickness of the GaN channel layer 103 is 300nm and the etching depth is 150nm. Two-dimensional electron gas is isolated between devices. Four HEMT transistors 2 are formed on the AlGaN / GaN-based thin film. The area size of the transistor 2 is 300um*200um.

[0052] (3) The GaN capping layer 106 of the HEMT transistor 2 obtained in step (2) is etched to etch out the positions of the source 201, drain 202, metal connection line 204 and gate metal 205 of the HEMT. The upper surface of the AlGaN barrier layer is exposed at the positions of the source 201, drain 202, metal connection line 204 and gate metal 205. Metal is sputtered on the GaN capping layer and the AlGaN barrier layer to form ohmic contacts. Annealing is performed to form the source 201, drain 202, source 201, drain 202, metal connection line 204 and gate metal 205.

[0053] (4) Sputter metal Ni / Au to form gate metal 203 on the GaN capping layer 106 of the structure obtained in step (3), with a thickness of 5nm / 5nm and a width of 50nm;

[0054] (5) Sputter metal Ni / Au onto the structure obtained in step (4) as the final test connection port total source 401, total drain 402, and total gate 403 with a thickness of 100 / 200nm and a size of 300um*300um;

[0055] (6) A 15nm first silicon nitride insulating layer is deposited on the surface of the structure formed in step (5), and a photolithographic pattern is used to etch out the source 2 301, drain 2 302, total source 401, total drain 402, and total gate 403.

[0056] (7) In step (6), the lead between the two source electrodes is obtained by photolithography on the surface of the first silicon nitride insulating layer, and Ni / Au metal is deposited at 20 / 40nm as the second metal connection line;

[0057] (8) Continue to deposit a 15nm second silicon nitride insulating layer on top of step (7), and etch out the drain 2 302, total source 401, total drain 402 and total gate 403 in the photolithography pattern;

[0058] (9) Photolithographically etch the lead between drain electrode 302 on the surface of the second silicon nitride insulating layer obtained in step (8), and deposit Ni / Au metal, 20 / 40nm, as metal interconnect 304;

[0059] (10) Continue to deposit a 10nm third silicon nitride insulating layer on the structure of step (9), and etch out the total source 401, total drain 402 and total gate 403 through photolithography.

[0060] (11) Photolithographic pattern on the lower surface of the silicon substrate 101 obtained in step (10) is used to etch and expose the lower surface of the buffer layer 102 to form an opening. The area of ​​the etched region is 600um*600um.

[0061] (12) The silicon substrate 101 with the structure obtained in step (11) is bonded to the standard silicon wafer 100 using Au-Au bonding 110, so that the opening in step (11) forms a closed cavity with the silicon wafer.

[0062] In this case, the outer edge of the HEMT transistor extends 100 μm beyond the edge of the square thin film corresponding to the etched area.

[0063] By providing gate voltage and drain voltage, the leakage current, turn-on voltage, and IV output curve of the output device are analyzed under different air pressure and ultraviolet light irradiation conditions to obtain pressure sensitivity, photoelectric detection responsivity, and detectivity.

[0064] Record the current output value as I0 under no pressure, and the current output value as I under different pressures. d , (I d -I0) / I0 is the relative change in current under different pressures, ΔIds=I d -I0 represents the difference in output current between the initial air pressure and different air pressures. Therefore, the formula for calculating the sensitivity of the pressure sensor is:

[0065] S = Δ(ΔIds / I0) / ΔP;

[0066] In ultraviolet detection, the responsivity of the device is:

[0067]

[0068] The detection rate of the device is:

[0069]

[0070] Where R is the responsivity, D* is the detectivity, and I... P It is photocurrent, I D It is the dark current, Peffect is the effective power irradiated on the device, and A is the device area.

[0071] Depend on Figure 6 It can be seen that the device's turn-on voltage is around -3V, and when Vds is negative, the gate leakage current is in the nA range, indicating that the gate has a good turn-off effect. Figure 7 The pressure response results of Example 1 were used to calculate the sensitivity under different leakage pressures by using the output current under different air pressures. Under the working voltage of Vgs = -3V and Vds = 3.0V, the sensitivity was 11.45% / kPa, indicating that it has a good response effect to pressure. Figure 8 The photoelectric detection performance of Example 1 has a maximum responsivity and detectivity of 326806.7593 A / W and 5.64E+13 Jones, respectively.

[0072] Durga's team (High Temperature AlGaN / GaN Membrane Based Pressure Sensors) achieved a sensitivity of 0.76% / kPa using an AlGaN / GaN thin film structure, which is far superior to the current industry sensitivity level. Wanglong Wu's team (Wafer-scale high sensitive UV photodetectors based on novel AlGaN / n-GaN / p-GaN heterostructure HEMT) achieved a responsivity of 9.12 A / W and a detectivity of 1.95E13 Jones using an AlGaN / n-GaN / p-GaN heterostructure HEMT. The comparison shows that the present invention exhibits excellent response characteristics to ultraviolet light.

[0073] Example 2

[0074] The difference between Example 2 and Example 1 is that the thickness of the gate metal Ni / Au in step (4) is 50 / 100 nm.

[0075] To verify the performance of the device, it was tested under the same conditions as in Example 1. Figure 9The diagram shows the pressure sensitivity and photoelectric detection performance of Example 2. Due to the change in the gate metal thickness, the ultraviolet light incident rate decreases, the photocurrent decreases, and the dark current does not change much, resulting in a decrease in responsivity and detectivity. The effect deteriorates after the gate metal thickness is changed.

[0076] Depend on Figure 9 It can be seen that when used as a pressure sensor, the sensitivity of Vgs=-3V and Vds=3V is still 10.40% / kPa, which is almost unaffected by the thickness of the gate electrode metal; however, it has a huge impact on ultraviolet light. By measuring the bright and dark currents under different light intensities, the maximum values ​​of responsivity and detectivity are calculated to be 81682.11816 A / W and 1.15E+13 Jones, respectively, which is almost 1 / 4 of that of the example.

[0077] Comparative Example 1

[0078] The difference between Comparative Example 1 and Example 1 is that, relative to the square thin film corresponding to the etched area, the HEMT transistor is located inside the thin film, and its outer edge is 30 μm away from the edge of the square thin film.

[0079] The pressure and ultraviolet light test conditions were still applied as in Example 1, and the change in output current Ids was observed as a standard for measuring device performance.

[0080] Figure 10 To compare the pressure response effect of Example 1, when the HEMT was completely transferred to the interior of the thin film region, it can be seen that under the same test conditions, the output current under different air pressures decreased, and the current change between the same air pressure difference also decreased, resulting in a decrease in sensitivity to air pressure. At the same time, after being transferred to the interior of the thin film region, due to the film's own gravity and the opposite piezoelectric polarization directions of the film center and edge, the 2DEG concentration and mobility in the natural state decreased. This resulted in a decrease in the 2DEG concentration induced by the same power of light in photodetector, leading to a decrease in photocurrent, which further reduced the photodetector responsivity and detectivity.

[0081] Depend on Figure 10 It can be seen that the current still shows an increasing trend with increasing air pressure, but the increase in current decreases under the same air pressure interval, further leading to a decrease in pressure sensitivity. The sensitivity drops to 7.64% / kPa when Vgs = -3V and Vds = 3V. Simultaneously, due to the HEMT shifting to the interior of the thin film region and occupying its center, the film slightly indents due to gravity. The center and edge of the film exhibit opposite piezoelectric polarization effects when subjected to the same pressure direction, resulting in a decrease in 2GEG concentration, reduced mobility, and decreased photocurrent under natural conditions. Consequently, both responsivity and detectivity decrease simultaneously. The maximum responsivity and detectivity are 263500.7087 A / W and 4.21E+13 Jones, respectively. Figure 11 .

[0082] In summary, the gate thickness of 5nm / 5nm and the placement of four HEMTs across the edge of the thin film in Example 1 are beneficial to the improvement of the device's pressure sensitivity and photoelectric response.

[0083] The embodiments provided above are not intended to limit the scope of the invention, nor are the described steps intended to limit the order of execution. Any obvious modifications made to the invention by those skilled in the art based on existing common knowledge also fall within the scope of protection defined by the claims.

Claims

1. An AlGaN / GaN thin-film sensor with enhanced sensitivity, enabling simultaneous monitoring of ultraviolet light and pressure, characterized in that, The sensor includes an AlGaN / GaN-based thin film deposited on the upper surface of a silicon substrate. A square groove is formed on the lower surface of the silicon substrate. The position on the AlGaN / GaN-based thin film corresponding to the square groove is the square thin film region of the sensor. HEMT transistors are respectively disposed at the center of the four sides of the square thin film region. The source or drain of two adjacent HEMT transistors is connected by a metal connection line and connected to the source or drain of two. The source or drain is disposed at the four vertices of the AlGaN / GaN square thin film. The two source transistors are diagonally disposed and connected to the total source by a metal connection line. The two drain transistors are diagonally disposed and connected to the total drain by a metal connection line. The gate metals of two opposing HEMT transistors are connected by a gate metals and connected to the total gate. A sealed cavity is formed between the square groove and the silicon wafer.

2. The sensor according to claim 1, characterized in that, The outer edge of the HEMT transistor extends 50–100 μm beyond the square thin film region, and the area of ​​the square thin film region is (500–700) μm * (500–700) μm.

3. The sensor according to claim 1, characterized in that, The AlGaN / GaN-based thin film includes a buffer layer, a GaN channel layer, an AlN insertion layer, an AlGaN barrier layer, and a GaN capping layer sequentially deposited on a silicon substrate. The AlGaN / GaN-based thin film is etched to form four HEMT transistors.

4. The sensor according to claim 3, characterized in that, The HEMT transistor has a size of (200-400) μm * (200-400) μm. The AlGaN / GaN-based thin film is etched from the top to the GaN channel layer, and the etching depth of the GaN channel layer accounts for 50-100% of the total thickness of the GaN channel layer.

5. The sensor according to claim 3, characterized in that, The AlGaN / GaN-based thin film has a thickness of 3–5 μm, wherein the GaN channel layer has a thickness of 0.3–0.4 μm.

6. The sensor according to claim 1, characterized in that, The stacked structure of the source electrode 1, drain electrode 1, source electrode 2, drain electrode 2, metal interconnect line 1, and gate metal 2 is Ti / Al / Ni / Au, with thicknesses of 20 / 160 / 55 / 45nm respectively.

7. The sensor according to claim 1, characterized in that, The gate metal has a Ni / Au material stacking structure with a thickness of 5nm / 5nm and a width of 50-100nm.

8. A method for fabricating an AlGaN / GaN thin-film sensor with enhanced sensitivity and enabling simultaneous ultraviolet and pressure monitoring as described in any one of claims 1 to 7, characterized in that, Includes the following steps: (1) A buffer layer, a GaN channel layer, an AlN insertion layer, an AlGaN barrier layer, and a GaN capping layer are sequentially formed on the upper surface of a silicon substrate to obtain an AlGaN / GaN-based thin film. (2) Etch the AlGaN / GaN-based thin film obtained in step (1) from the top until the GaN channel layer is etched, isolating the two-dimensional electron gas between devices, and forming four HEMT transistors on the AlGaN / GaN-based thin film. (3) The GaN capping layer of the HEMT transistor obtained in step (2) is etched to etch out the positions of the first source, the first drain and the first metal connection line of the HEMT. The upper surface of the AlGaN barrier layer is exposed at the positions of the first source, the first drain and the first metal connection line. Metal is sputtered on the GaN capping layer and the AlGaN barrier layer to form ohmic contacts. The first source, the first drain, the second source, the second drain, the first metal connection line and the second gate metal are formed by annealing. (4) Sputter metal Ni / Au onto the GaN capping layer of the structure obtained in step (3) to form gate metal 1; (5) Sputter metal Ni / Au onto the structure obtained in step (4) as the final test connection port source, gate and drain; (6) A first silicon nitride insulating layer is deposited on the surface of the structure formed in step (5), and a photolithographic pattern is used to etch out the source two, drain two, total source, total drain and total gate portions; (7) In step (6), the lead wire between the source electrode and the source electrode is photolithographically formed on the surface of the first silicon nitride insulating layer, and Ni / Au metal is deposited at 20 / 40nm. (8) Continue to deposit a second silicon nitride insulating layer on top of step (7), and etch out the drain, source, drain and gate portions of the photolithography pattern; (9) Photolithographically etch the lead between the drain electrodes on the surface of the second silicon nitride insulating layer obtained in step (8), and deposit Ni / Au metal at 20 / 40nm as the metal connection line three; (10) Continue to deposit a third silicon nitride insulating layer on the structure of step (9), and etch out the total source, total drain and total gate portions of the photolithography pattern; (11) Photolithographic pattern on the lower surface of the silicon substrate of the structure obtained in step (10) is used to etch and expose the lower surface of the buffer layer to form an opening; (12) The silicon substrate with the structure obtained in step (11) is bonded to a standard silicon wafer using Au-Au bonding, so that the opening in step (11) forms a closed cavity with the silicon wafer.

9. The preparation method according to claim 8, characterized in that, The thicknesses of the first silicon nitride insulating layer, the second silicon nitride insulating layer, and the third silicon nitride insulating layer are all 10–30 nm.

10. The application of the AlGaN / GaN thin-film sensor according to any one of claims 1 to 7 in industrial detection and aerospace fields.

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