Amorphous indium gallium zinc oxide thin film transistor room temperature hydrogen sensor and integrated preparation method

Abstract

The invention belongs to the field of gas sensors, and discloses an amorphous indium gallium zinc oxide thin film transistor room temperature hydrogen sensor and an integrated preparation method. The hydrogen sensor comprises a gate electrode, a gate dielectric layer, an amorphous indium gallium zinc oxide film, an aluminum oxide functional layer and a gas sensitive layer which are sequentially arranged from bottom to top, a source electrode and a drain electrode are arranged between the gate dielectric layer and the amorphous indium gallium zinc oxide thin film, and the amorphous indium gallium zinc oxide thin film is in contact with the gate dielectric layer and is connected with the source electrode and the drain electrode through ohmic contact. A gas-sensitive signal is generated through the catalytic reaction of the gas-sensitive layer and hydrogen, the channel current of the amorphous indium gallium zinc oxide film is changed through charge transfer or a capacitance effect, the aluminum oxide functional layer repairs the surface defects of the amorphous indium gallium zinc oxide, the hydrogen detection performance is enhanced, and the detection sensitivity is improved. And a signal of the gas sensitive layer is allowed to be coupled to a channel of the amorphous indium gallium zinc oxide film, so that the hydrogen sensor has the characteristics of high sensitivity, working at room temperature and ultra-small volume.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of gas sensors, and more particularly relates to an amorphous indium gallium zinc oxide thin film transistor room temperature hydrogen sensor and an integrated preparation method. BACKGROUND

[0002] Hydrogen is a clean energy with great potential and an important industrial raw material, and its application is becoming more and more widespread. However, hydrogen has a very wide explosion limit and a very low ignition energy, and the risk of leakage is high, so it is very important to develop a sensor that can quickly and sensitively detect hydrogen to ensure the safe production, transportation and use of hydrogen energy.

[0003] The current mainstream semiconductor hydrogen sensor usually relies on the resistance change of metal oxide material at high temperature to detect hydrogen. This working mode leads to high energy consumption, the need for complex heating elements and temperature control systems, which not only increases the volume and cost, but also may cause safety hazards. Although optical hydrogen sensors can work at room temperature, they are complex to manufacture, high in cost, and difficult to popularize.

[0004] Thin film transistor gas sensors use planar manufacturing processes, have the characteristics of simple process, small size, and are suitable for large-scale manufacturing. The transistor structure has an amplification effect on the sensing signal, which can significantly increase the sensitivity of the sensor. The thin film transistor hydrogen sensor still has the following technical problems: the surface of the semiconductor is weak in chemical activity at room temperature, and the sensitivity to hydrogen is low; the interface defect density between the gas sensitive material and the semiconductor layer is high, which leads to degradation of device performance; the preparation process of the gas sensitive material is not compatible with the preparation process of the transistor, and integrated manufacturing is difficult. Therefore, it is necessary to improve the existing thin film transistor gas sensor. SUMMARY

[0005] In view of the above defects or improvement needs of the prior art, the present application provides an amorphous indium gallium zinc oxide thin film transistor room temperature hydrogen sensor and an integrated preparation method, thereby solving the technical problems of existing gas sensors such as high working temperature, low sensitivity, and complex structure.

[0006] To achieve the purpose of the present application, according to the first aspect of the present application, an amorphous indium gallium zinc oxide thin film transistor room temperature hydrogen sensor is provided, which comprises a gate electrode, a gate dielectric layer, an amorphous indium gallium zinc oxide thin film, an aluminum oxide functional layer and a gas sensitive layer arranged in order from bottom to top; a source-drain electrode is also arranged between the gate dielectric layer and the amorphous indium gallium zinc oxide thin film; and the amorphous indium gallium zinc oxide thin film is in contact with the gate dielectric layer, and the amorphous indium gallium zinc oxide thin film is connected to the source-drain electrode through ohmic contact.

[0007] As a preferred embodiment of the present application, the aluminum oxide functional layer is prepared by an atomic layer deposition process, wherein the number of cycles of the atomic layer deposition process is 20-400 cycles.

[0008] As a preferred embodiment of the present application, the precursor sources of the atomic layer deposition process are trimethylaluminum and deionized water, and each deposition cycle includes one pulse of trimethylaluminum and one pulse of deionized water.

[0009] As a preferred embodiment of the present application, when the number of cycles of the atomic layer deposition process of the aluminum oxide functional layer is 20-100 cycles, the gas sensitive layer is a nano-particle structure.

[0010] When the number of cycles of the atomic layer deposition process of the aluminum oxide functional layer is 100-400 cycles, the gas sensitive layer is a thin film structure.

[0011] The gas sensitive layer is prepared by an atomic layer deposition process to form the nano-particle structure, and the gas sensitive layer is prepared by a magnetron sputtering deposition process or an atomic layer deposition process to form the thin film structure.

[0012] As a preferred embodiment of the present application, the amorphous indium gallium zinc oxide thin film is prepared by annealing after magnetron sputtering; and the thickness of the amorphous indium gallium zinc oxide thin film is 10-70 nm.

[0013] As a preferred embodiment of the present application, the gas sensitive layer is metal palladium or an alloy thereof.

[0014] As a preferred embodiment of the present application, the gate electrode and the gate dielectric layer are a silicon wafer with one side oxidized, wherein the pure silicon wafer in the silicon wafer with one side oxidized serves as the gate electrode, and the silicon oxide layer serves as the gate dielectric layer.

[0015] According to a second aspect of the present application, an integrated preparation method of an amorphous indium gallium zinc oxide thin film transistor room temperature hydrogen sensor is provided, comprising the following steps:

[0016] (1) sequentially preparing a gate electrode and a gate dielectric layer, and then preparing a source-drain electrode on part of the surface of the gate dielectric layer;

[0017] (2) preparing an amorphous indium gallium zinc oxide thin film layer on the source-drain electrode and the gate dielectric layer, and performing annealing;

[0018] (3) preparing an aluminum oxide functional layer on the amorphous indium gallium zinc oxide thin film layer, and preparing a gas sensitive layer on the aluminum oxide functional layer.

[0019] As a preferred embodiment of the present application, in step (2), the amorphous indium gallium zinc oxide thin film layer is prepared on the source-drain electrode and the gate dielectric layer by magnetron sputtering and then annealed to room temperature after heating; wherein the heating rate is 5℃ / min or less, and the heating temperature is 200-400℃.

[0020] As a preferred embodiment of the present application, in step (3), the aluminum oxide functional layer is prepared on the amorphous indium gallium zinc oxide thin film layer by an atomic layer deposition process, wherein the number of cycles of the atomic layer deposition process is 20-400 cycles.

[0021] Overall, compared with the prior art, the above technical solution conceived by the present application mainly has the following technical advantages:

[0022] 1. The amorphous indium gallium zinc oxide thin film transistor room temperature hydrogen sensor provided by the present application generates a gas sensitive signal through the catalytic reaction of the gas sensitive layer with hydrogen, and changes the amorphous indium gallium zinc oxide thin film channel current through charge transfer or capacitance effect. The aluminum oxide functional layer and the indium gallium zinc oxide are both metal oxides, have high matching degree, repair the surface defects of the amorphous indium gallium zinc oxide, have passivation effect on the amorphous indium gallium zinc oxide, improve the mobility of the amorphous indium gallium zinc oxide, and thus improve the signal strength generated by the gas sensitive reaction injection charge, and allow the gas sensitive layer signal to be coupled to the channel of the amorphous indium gallium zinc oxide thin film, so that the hydrogen sensor of the present application has the characteristics of high sensitivity, room temperature operation and ultra-small volume.

[0023] 2. The aluminum oxide functional layer is preferably prepared by an atomic layer deposition process, wherein the number of cycles of the atomic layer deposition process is 20-400 cycles, and the thickness of the prepared aluminum oxide functional layer is appropriate. More preferably, the thickness of the aluminum oxide functional layer matches the morphology of the gas sensitive layer, specifically, when the gas sensitive layer is in a thin film form, the corresponding number of cycles of the aluminum oxide layer is 200-400 cycles, too thick will reduce the capacitance effect, resulting in a decrease in sensitivity, and too thin will cause the aluminum oxide layer to be prone to electrical breakdown, causing short circuit of the indium gallium zinc oxide thin film; when the gas sensitive layer is in a nanoparticle form, the number of cycles of the aluminum oxide layer is 20-50 cycles, too thick will hinder charge transfer, resulting in a decrease in sensitivity, and too thin will reduce the defect passivation effect of the aluminum oxide layer, resulting in a decrease in device performance.

[0024] 3. The high-temperature slow heating annealing of the amorphous indium gallium zinc oxide thin film in the present application can regulate the oxygen vacancy concentration, reduce the sub-threshold swing, and enhance the amplification effect on the sensing signal.

[0025] 4. The gas sensitive layer of the present application uses Pd or its alloy, which has high selectivity and high catalytic activity for hydrogen, and is conducive to room temperature sensing.

[0026] 5、The present application takes thin film transistor as device basis, and the thin film transistor, the aluminum oxide functional layer and the gas sensitive layer can adopt CMOS compatible process to complete integrated preparation, and can realize super small volume, large batch integrated manufacturing. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 The subthreshold swing of the indium gallium zinc oxide thin film transistor with different annealing temperatures in example 1 in the present application is compared;

[0028] Figure 2 The XPS spectrum of the indium gallium zinc oxide (IGZO) thin film with different annealing temperatures in example 1 in the present application is shown in the figure, wherein Figure 2 (a) corresponds to the IGZO thin film prepared under the annealing condition at room temperature, (b) corresponds to the IGZO thin film prepared under the annealing condition at 200 DEG C, (c) corresponds to the IGZO thin film prepared under the annealing condition at 400 DEG C, and (d) corresponds to the IGZO thin film prepared under the annealing condition at 600 DEG C;

[0029] Figure 3 The on-off ratio of the indium gallium zinc oxide thin film transistor with different annealing temperatures in example 1 in the present application is shown in the figure;

[0030] Figure 4 The subthreshold swing of the indium gallium zinc oxide thin film transistor with different heating rates in example 1 in the present application is shown in the figure;

[0031] Figure 5 The transfer characteristic of the indium gallium zinc oxide thin film transistor with different ALD aluminum oxide cycle numbers in example 2 in the present application is shown in the figure;

[0032] Figure 6 The mobility of the indium gallium zinc oxide thin film transistor with different aluminum oxide layers in example 2 in the present application is shown in the figure;

[0033] Figure 7 The subthreshold swing of the indium gallium zinc oxide thin film transistor with different aluminum oxide layers in example 2 in the present application is shown in the figure;

[0034] Figure 8 The sensor section schematic diagram of example 3.1 of the present application is shown in the figure;

[0035] Figure 9 The gas sensitive performance test of the sensor of example 3.1 of the present application to hydrogen at normal temperature and pressure is shown in the figure;

[0036] Figure 10 The response value-concentration fitting relationship of the sensor of example 3.1 of the present application is shown in the figure;

[0037] Figure 11 The selectivity test of the sensor of example 3.1 of the present application at normal temperature and pressure is shown in the figure;

[0038] Figure 12 The gas sensing performance of the sensor of the embodiment 3.2 of the present application to hydrogen was tested at normal temperature and pressure.

[0039] Figure 13 The cross-sectional schematic diagram of the sensor of the embodiment 3.3 of the present application was shown.

[0040] Figure 14 The gas sensing performance of the sensor of the embodiment 3.3 of the present application to hydrogen was tested at normal temperature and pressure.

[0041] Figure 15 The repeatability of the sensor of the embodiment 3.3 of the present application to hydrogen was tested at normal temperature and pressure.

[0042] Figure 16 The response value-concentration fitting relationship of the sensor of the embodiment 3.3 of the present application was shown.

[0043] Figure 17 The gas sensing performance of the sensor of the embodiment 3.4 of the present application to hydrogen was tested at normal temperature and pressure. DETAILED DESCRIPTION

[0044] In order to make the objects, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and do not limit the present application. In addition, the technical features involved in each embodiment of the present application described below can be combined with each other as long as they do not conflict with each other.

[0045] The present application aims to provide a small volume, high sensitivity room temperature hydrogen sensor and a preparation method, which solves the problems of high working temperature, low sensitivity and complex structure of the existing hydrogen sensor, can realize mass production, and meets the demand of hydrogen concentration monitoring and leakage detection. In order to achieve the above purpose, the present application provides a thin film transistor room temperature hydrogen sensor based on aluminum oxide functional layer and an integrated preparation method.

[0046] An integrated preparation method of an amorphous indium gallium zinc oxide thin film transistor room temperature hydrogen sensor, comprising the following steps:

[0047] The substrate was cleaned and dried, specifically: the substrate was ultrasonically cleaned with ethanol, acetone, isopropanol and deionized water in sequence, for 10 minutes.

[0048] The substrate is made of high-resistance material, preferably high-resistance silicon wafer; the gate electrode is made of electrode material prepared on the substrate, preferably Ti and amorphous silicon, preferably 20-60 nm in thickness, to provide good conductivity and meet process compatibility; the gate dielectric layer is made of insulating material prepared on the gate electrode, preferably aluminum oxide and silicon oxide, preferably 50-300 nm in thickness, to ensure insulation performance and gate control capability. For example, the gate electrode and the gate dielectric layer are made of single-side oxidized low-resistance silicon, the low-resistance silicon part serving as the gate electrode, preferably 100-1000 um in thickness; the oxide layer serving as the gate dielectric layer, preferably 50-300 nm in thickness.

[0049] The source-drain electrode is prepared on part of the surface of the substrate, specifically: using the corresponding target material of electrode material, prepared by magnetron sputtering, the work function of the source-drain electrode material is lower than that of the amorphous indium gallium zinc oxide (IGZO) thin film, which is a conductive material that can form ohmic contact with IGZO, to reduce contact resistance and improve signal strength, and the preferred material includes Ti, ITO.

[0050] The amorphous IGZO active layer is prepared on the source-drain electrode and the surface of the substrate, specifically: using IGZO ceramic target material, prepared by magnetron sputtering, and then annealed by high-temperature slow heating. The preferred thickness of the IGZO thin film is 10-70 nm, and too thick will reduce the gate control capability, and too thin will increase the surface scattering and reduce the device performance.

[0051] The magnetron sputtering specifically includes: the annealing process uses high-temperature slow heating annealing, specifically, the heating rate is 5℃ / min or lower, and the heating / annealing temperature range is 200-400℃. The preferred parameters are as follows: the heating rate is 1℃ / min, and the heating / annealing temperature is 400℃.

[0052] The aluminum oxide functional layer is prepared on the amorphous IGZO active layer, specifically: the aluminum oxide functional layer is prepared by atomic layer deposition (ALD) process, the precursor source is trimethylaluminum and deionized water, each deposition cycle includes one trimethylaluminum pulse and one deionized water pulse, and the cycle number of the atomic layer deposition process is 20-400 cycles. Aluminum oxide and IGZO are both metal oxides, with high matching degree, which can effectively reduce the surface defect state density of IGZO and improve the mobility, to enhance the signal amplification effect of IGZO; the aluminum oxide surface is rich in Lewis acid sites, which can be used as a binding site to receive hydrogen from the gas-sensitive layer; the aluminum oxide can transmit the electrical signal generated by the surface hydrogen to the IGZO thin film through charge transmission or capacitive coupling.

[0053] The gas-sensitive layer is prepared on the aluminum oxide functional layer, specifically: the gas-sensitive layer is Pd-based material, deposited by ALD or magnetron sputtering.

[0054] The preparation process of the gas sensitive layer and the aluminum oxide functional layer is matched, preferably: if the nanometer particle shaped gas sensitive layer is deposited by ALD, the cycle number of the aluminum oxide functional layer should be 20-100 times, more preferably 20-50 times; if the thin film shaped gas sensitive layer is deposited by magnetron sputtering, the cycle number of the aluminum oxide functional layer should be 100-400 times, more preferably 200-400.

[0055] The ALD deposition scheme is as follows: the precursor source is Pd(hafc)2 and tert-butyl hydrazine, each deposition cycle includes one Pd(hafc)2 and one tert-butyl hydrazine pulse, and the total cycle number is less than 100 times. The gas sensitive layer deposited by the scheme is in a nanometer particle shape, and the sheet resistance is greater than 100 MΩ. The magnetron sputtering deposition scheme is as follows: a Pd metal target is used, and the thickness is 10-100 nm, preferably 40 nm. The gas sensitive layer deposited by the scheme is in a thin film shape, and the sheet resistance is less than 100 kΩ.

[0056] When the amorphous indium gallium zinc oxide thin film transistor room temperature hydrogen sensor of the application works, a fixed gate voltage is loaded to make the amorphous IGZO thin film transistor work in a sub-threshold region to amplify the gas sensitive signal. A fixed positive voltage is loaded to the drain electrode, and the source electrode is grounded to provide working current. Hydrogen is decomposed into hydrogen atoms by the catalytic action of the gas sensitive layer to generate a gas sensitive electric signal. The electric signal is transmitted to the IGZO film through the aluminum oxide functional layer to affect the IGZO channel carrier concentration to generate a detectable current change. The sensor can work at room temperature, has a small volume, is suitable for batch production, and provides a new strategy for existing hydrogen sensors.

[0057] The above method is further described in detail in combination with the accompanying drawings and specific examples. It should be understood that the following examples are only used to explain the application, and the scope of protection of the application is not limited thereto.

[0058] Example 1:

[0059] An IGZO thin film transistor includes a single-sided oxidized low-resistance silicon substrate and an amorphous IGZO thin film arranged in sequence from bottom to top. The source electrode and the drain electrode are made of conductive material and have ohmic contact with the amorphous IGZO. In this embodiment, the source electrode and the drain electrode are metal Ti thin films prepared by magnetron sputtering, and the thickness is 30 nm.

[0060] The amorphous IGZO thin film is prepared by magnetron sputtering and then annealed in air to obtain high-temperature annealing, wherein the heating rate is 1-10 ℃ / min, the annealing temperature is room temperature to 600 ℃, and the thickness is 40 nm.

[0061] As Figure 1The subthreshold swing of the IGZO thin film transistor at different annealing temperatures is shown, and the test results show that the subthreshold swing of the IGZO thin film transistor annealed at 400 DEG C is the lowest, and the signal amplification effect is stronger, and the performance is optimal.

[0062] As shown in Figure 2 The XPS spectrum of the IGZO film at different annealing temperatures is shown, and the test results show that the oxygen vacancy content of the IGZO film is significantly reduced after annealing. On the one hand, the oxygen vacancy as a defect state will hinder the movement of carriers and reduce the performance of the device; on the other hand, the oxygen vacancy is the source of IGZO carriers, and the content is too low to cause the conductivity of IGZO to decrease. Therefore, the device annealed at 400 DEG C shows the best overall performance.

[0063] As shown in Figure 3 The on-off ratio of the IGZO thin film transistor at different annealing temperatures is shown, and the results show that the IGZO annealed at 400 DEG C has the highest on-off ratio, and the IGZO annealed at 200 DEG C has the lowest on-off ratio, which proves that the too low oxygen vacancy content is not conducive to the conduction of the device.

[0064] As shown in Figure 4 The subthreshold swing of the IGZO thin film transistor at different heating rates is shown, and the test results show that the subthreshold swing of the IGZO thin film transistor with a heating rate of 1 DEG C / min is significantly smaller than that of the IGZO thin film transistor with a heating rate of 10 DEG C / min, which proves that low-speed heating can improve the performance of the transistor.

[0065] As can be seen from Example 1, the amorphous IGZO film can be prepared by the preparation method of the present application, and the signal amplification capability of the amorphous IGZO thin film transistor prepared under the condition of a heating rate of 1 DEG C / min and an annealing temperature of 400 DEG C is more optimal, and is more suitable for a gas sensor. The method is used in the following examples for subsequent sensors.

[0066] Example 2:

[0067] An IGZO thin film transistor with an aluminum oxide functional layer comprises, from bottom to top, a single-sided oxidized low-resistance silicon substrate, an amorphous IGZO film and an aluminum oxide functional layer. The source and drain are made of conductive material and have ohmic contact with the amorphous IGZO. In this embodiment, the source and drain are metal Ti films prepared by magnetron sputtering, and the thickness is 30 nm.

[0068] The amorphous IGZO film is prepared by magnetron sputtering and then annealed in air, and the parameters are as follows: the heating rate is 1 DEG C / min, the annealing temperature is 400 DEG C, and the thickness is 40 nm.

[0069] The aluminum oxide functional layer is prepared by ALD, and the dose is 20 cycles or 100 cycles, and the corresponding thicknesses are 0.9 nm and 9.8 nm, respectively.

[0070] Transfer characteristics of IGZO thin-film transistors without deposited alumina, such as Figure 5 As shown in device ①, the transfer characteristics of the IGZO thin film transistor with 20 cycles of aluminum oxide deposition are as follows: Figure 5 As shown in device ②, the transfer characteristics of the IGZO thin film transistor with 100 cycles of aluminum oxide deposition are as follows: Figure 5 As shown in device ③.

[0071] The transfer characteristic curves were all measured using a semiconductor analyzer at room temperature and pressure. For example... Figure 6 The figure shows the mobility of IGZO thin-film transistors with different alumina layers. The device mobility was extracted from the transfer characteristic curves. The results show that the device mobility increases after alumina deposition, indicating that the defect state density decreases, which is beneficial for the transport of injected electrons. Figure 7 The figure shows the subthreshold swing of IGZO thin film transistors with different alumina layers. The subthreshold swing of the device was extracted from the transfer characteristic curve. The results show that the subthreshold swing is reduced after alumina deposition, which in principle provides a stronger amplification effect for gas-sensitive signals.

[0072] As can be seen from Example 2, the alumina prepared by the method of the present invention has a surface defect passivation effect on IGZO, which can improve transistor performance, and this is the basis for good gas-sensing performance.

[0073] Example 3:

[0074] Example 3.1:

[0075] like Figure 8 As shown, a thin-film transistor room-temperature hydrogen sensor based on an alumina functional layer includes, from bottom to top, a single-sided low-resistivity silicon oxide substrate, an amorphous IGZO thin film, an ultrathin alumina functional layer, and a metal Pd nanoparticle gas-sensitive layer. The source and drain are made of conductive materials and have ohmic contacts with the amorphous IGZO. In this embodiment, the source and drain are metal Ti thin films, prepared by magnetron sputtering, with a thickness of 30 nm.

[0076] The amorphous IGZO thin film was prepared by magnetron sputtering with a thickness of 40 nm and annealed in air with the following parameters: heating rate of 1℃ per minute and annealing temperature of 400℃.

[0077] The alumina functional layer was prepared by ALD at a dose of 20 cycles and had a thickness of 0.9 nm.

[0078] The Pd nanoparticle gas-sensitive layer was prepared by ALD at a dose of 50 cycles. The morphology of the gas-sensitive layer cannot be selected; otherwise, the IGZO will be short-circuited by the gas-sensitive film, and an effective signal cannot be measured.

[0079] In operation, the low-resistance silicon substrate serves as a gate electrode, a fixed gate voltage is loaded to make the amorphous IGZO thin film transistor work in the subthreshold region to amplify the gas sensitive signal. A fixed positive voltage is loaded to the drain electrode, and the source electrode is grounded to provide working current.

[0080] As shown in Figure 9 The gas sensitive performance test of the sensor under normal temperature and pressure shows that the sensor has high sensitivity, and the relative response value of 1000ppm hydrogen is 137, and the detection lower limit is lower than 20ppm.

[0081] As shown in Figure 10 The response value-concentration fitting relationship of the sensor shows that the response value is proportional to the square root of the hydrogen concentration, which proves that the gas sensitive response comes from the reaction process of hydrogen decomposition into hydrogen atoms.

[0082] As shown in Figure 11 The selectivity test of the sensor under normal temperature and pressure shows that the sensor has low response to other hydrogen-containing interference gases, which ensures the accuracy of hydrogen detection.

[0083] In this embodiment, the working principle of the sensor is that hydrogen is decomposed into hydrogen atoms by the catalytic action of metal Pd nanoparticles, and this process injects electrons into the amorphous IGZO thin film through the ultra-thin aluminum oxide functional layer, changes the carrier concentration of the amorphous IGZO thin film, and further produces source-drain current change.

[0084] As can be seen from embodiment 3.1, the thin film transistor room temperature hydrogen sensor can be prepared by the preparation method of the application, and the nanoparticles Pd has strong catalytic performance, so that the sensor has high sensitivity and high selectivity, and is suitable for detection of low concentration hydrogen.

[0085] Embodiment 3.2:

[0086] A thin film transistor room temperature hydrogen sensor, comprising a single-sided oxidized low-resistance silicon substrate, an amorphous IGZO thin film and a metal Pd nanoparticle gas sensitive layer arranged in order from bottom to top. The source electrode and the drain electrode are made of conductive material and have ohmic contact with the amorphous IGZO. In this embodiment, the source electrode and the drain electrode are metal Ti thin films prepared by magnetron sputtering, and the thickness is 30nm.

[0087] The amorphous IGZO thin film is prepared by magnetron sputtering, and the thickness is 40nm. The annealing parameters in air are as follows: the heating rate is 1℃ per minute, and the annealing temperature is 400℃.

[0088] The metal Pd nanoparticle gas sensitive layer is prepared by ALD, and the dose is 50 cycles.

[0089] In operation, the low-resistance silicon substrate is used as a gate electrode, a fixed gate voltage is loaded, and the amorphous IGZO thin film transistor is operated in a sub-threshold region to amplify the gas sensitive signal. The drain electrode is loaded with a fixed positive voltage, and the source electrode is grounded to provide working current.

[0090] As shown in Figure 12 the gas sensitive performance test of the sensor on hydrogen at normal temperature and pressure, the test results show that the sensor has low response to hydrogen and low degree of distinction to different concentrations of hydrogen. Compared with Example 3.1, it can be seen that the aluminum oxide layer plays an important role in improving the sensitivity.

[0091] Example 3.3:

[0092] As shown in Figure 13 a thin film transistor room temperature hydrogen sensor based on an aluminum oxide functional layer, including a single-sided oxidized low-resistance silicon substrate, an amorphous IGZO thin film, an aluminum oxide functional layer and a metal Pd thin film gas sensitive layer arranged in order from bottom to top. The source and drain electrodes are made of conductive materials and have ohmic contact with the amorphous IGZO. In this embodiment, the source and drain electrodes are metal Ti thin films prepared by magnetron sputtering, with a thickness of 30 nm.

[0093] The amorphous IGZO thin film is prepared by magnetron sputtering, with a thickness of 40 nm, and is annealed in air. The parameters are as follows: the heating rate is 1℃ per minute, and the annealing temperature is 400℃.

[0094] The aluminum oxide functional layer is prepared by ALD, with a dose of 400 cycles and a thickness of 42 nm, to repair defects in the amorphous IGZO thin film and isolate electron transmission.

[0095] The metal Pd thin film gas sensitive layer is prepared by magnetron sputtering, with a thickness of 40 nm.

[0096] In operation, the low-resistance silicon substrate is grounded, a fixed voltage is loaded on the metal Pd thin film, and the amorphous IGZO thin film transistor is operated in a sub-threshold region to amplify the gas sensitive signal. The drain electrode is loaded with a fixed positive voltage, and the source electrode is grounded to provide working current.

[0097] As shown in Figure 14 the gas sensitive performance test of the sensor on hydrogen at normal temperature and pressure, the test results show that the sensor has good response to hydrogen, and the relative response to 1000ppm hydrogen is 3.2, and the detection lower limit is less than 100ppm.

[0098] As shown in Figure 15 the repeatability test of the sensor on hydrogen at normal temperature and pressure, the test results show that the sensor has stable performance and is conducive to long-term detection.

[0099] As shown in Figure 16The response value-concentration fitting relationship of the sensor is shown, and the fitting result shows that the response value is proportional to the square root of the hydrogen concentration, which proves that the gas sensitive response is derived from the reaction process of hydrogen gas decomposing into hydrogen atoms. The relationship is consistent with Example 3.1, which shows that the gas sensitive response mechanism does not change in essence, and only the signal transmission mode is different.

[0100] In this embodiment, the working principle of the sensor is that hydrogen is decomposed into hydrogen atoms by the catalytic action of the metal Pd thin film, and migrates to the surface of the alumina, combines with the Lewis acid site, generates a dipole layer, changes the carrier concentration of the amorphous IGZO thin film through the capacitive effect, and further generates a change in the source-drain current.

[0101] As can be seen from Example 3.3, the thin film transistor room temperature hydrogen sensor can be prepared by the preparation method of the application, the thin film gate structure has high stability, has good detection repeatability, and is suitable for continuous detection of hydrogen.

[0102] Example 3.4:

[0103] A thin film transistor room temperature hydrogen sensor based on an alumina functional layer, comprising a single-sided low-resistance silicon substrate, an amorphous IGZO thin film, an alumina functional layer and a metal Pd nanoparticle gas sensitive layer arranged in order from bottom to top. The source and drain are made of conductive material and have ohmic contact with the amorphous IGZO. In this embodiment, the source and drain are metal Ti thin films prepared by magnetron sputtering, and the thickness is 30 nm.

[0104] The amorphous IGZO thin film is prepared by magnetron sputtering, and the thickness is 40 nm. Annealing in air, parameters are as follows: the heating rate is 1℃ per minute, and the annealing temperature is 400℃.

[0105] The alumina functional layer is prepared by ALD, the dose is 400 cycles, and the thickness is 42 nm.

[0106] The metal Pd nanoparticle gas sensitive layer is prepared by ALD, and the dose is 50 cycles.

[0107] When working, the low-resistance silicon substrate serves as the gate electrode, a fixed gate voltage is loaded, the amorphous IGZO thin film transistor works in the sub-threshold region to amplify the gas sensitive signal. The drain electrode is loaded with a fixed positive voltage, and the source electrode is grounded to provide working current.

[0108] As Figure 17The gas sensitive performance test of the sensor to hydrogen at normal temperature and pressure is shown, and the test results show that the sensor has no response to hydrogen. Comparative Example 3.1 can show that the nano-particle Pd gas sensitive layer needs an ultra-thin alumina layer, otherwise the electron transport is blocked and the gas sensitive response cannot be generated. Comparative Example 3.3 can show that when the insulating alumina layer is used, the gas sensitive layer needs to be in a thin film form and be connected to a fixed voltage, otherwise the dipole layer generated by the gas sensitive response cannot affect the IGZO channel.

[0109] Obviously, various modifications and changes can be made to the present application by those skilled in the art without departing from the spirit and scope of the present application. Thus, it is intended that the present application cover the modifications and changes as long as they come within the scope of the appended claims and their equivalents. The above-described embodiments are only preferred embodiments of the present application, and the scope of protection is not limited thereto. Any equivalent replacement or transformation made by those skilled in the art based on the present application shall fall within the scope of protection of the present application.

Claims

1. An amorphous indium gallium zinc oxide thin-film transistor room temperature hydrogen sensor, characterized in that, The device includes, from bottom to top, a gate electrode, a gate dielectric layer, an amorphous indium gallium zinc oxide thin film, an aluminum oxide functional layer, and a gas-sensitive layer; a source / drain electrode is also disposed between the gate dielectric layer and the amorphous indium gallium zinc oxide thin film; and the amorphous indium gallium zinc oxide thin film is in contact with the gate dielectric layer, and the amorphous indium gallium zinc oxide thin film is connected to the source / drain electrode through an ohmic contact.

2. The amorphous indium gallium zinc oxide thin-film transistor room temperature hydrogen sensor according to claim 1, characterized in that, The alumina functional layer is prepared by an atomic layer deposition process, wherein the atomic layer deposition process consists of 20-400 cycles.

3. The amorphous indium gallium zinc oxide thin-film transistor room temperature hydrogen sensor according to claim 2, characterized in that, The precursor sources for the atomic layer deposition process are trimethylaluminum and deionized water, and each deposition cycle includes one trimethylaluminum pulse and one deionized water pulse.

4. The amorphous indium gallium zinc oxide thin-film transistor room temperature hydrogen sensor according to claim 2, characterized in that, When the atomic layer deposition process of the alumina functional layer has 20-100 cycles, the gas-sensitive layer has a nanoparticle structure. When the atomic layer deposition process of the alumina functional layer has 100-400 cycles, the gas-sensitive layer has a thin film structure. The gas-sensitive layer is fabricated into the nanoparticle structure using atomic layer deposition (ALD) technology, and the gas-sensitive layer is fabricated into the thin film structure using magnetron sputtering deposition (MSD) or atomic layer deposition (ALD) technology.

5. The amorphous indium gallium zinc oxide thin-film transistor room temperature hydrogen sensor according to claim 1, characterized in that, The amorphous indium gallium zinc oxide thin film is obtained by magnetron sputtering followed by annealing; the thickness of the amorphous indium gallium zinc oxide thin film is 10-70 nm.

6. The amorphous indium gallium zinc oxide thin-film transistor room temperature hydrogen sensor according to claim 1, characterized in that, The gas-sensitive layer is palladium or its alloy.

7. The amorphous indium gallium zinc oxide thin-film transistor room temperature hydrogen sensor according to claim 1, characterized in that, The gate electrode and the gate dielectric layer are single-sided oxidized silicon wafers, wherein the pure silicon wafer in the single-sided oxidized silicon serves as the gate electrode, and the silicon oxide layer serves as the gate dielectric layer.

8. An integrated fabrication method for an amorphous indium gallium zinc oxide thin-film transistor room temperature hydrogen sensor, characterized in that, Includes the following steps: (1) A gate electrode and a gate dielectric layer are prepared sequentially, and then a source and drain electrode is prepared on a portion of the surface of the gate dielectric layer; (2) An amorphous indium gallium zinc oxide thin film layer is prepared on the source / drain electrode and the gate dielectric layer, and then annealed; (3) An aluminum oxide functional layer is prepared on the amorphous indium gallium zinc oxide thin film layer, and a gas-sensitive layer is prepared on the aluminum oxide functional layer.

9. The integrated fabrication method of the amorphous indium gallium zinc oxide thin-film transistor room temperature hydrogen sensor according to claim 8, characterized in that, In step (2), the amorphous indium gallium zinc oxide thin film layer is prepared by magnetron sputtering on the source / drain electrodes and the gate dielectric layer, followed by heating and annealing to room temperature; wherein the heating rate is less than 5°C / min and the heating temperature is 200–400°C.

10. The integrated fabrication method of the amorphous indium gallium zinc oxide thin-film transistor room temperature hydrogen sensor according to claim 8, characterized in that, In step (3), an aluminum oxide functional layer is prepared on the amorphous indium gallium zinc oxide thin film layer by an atomic layer deposition process, wherein the atomic layer deposition process has 20-400 cycles.

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