Gas sensing device based on thin film field effect transistor and preparation method thereof

Abstract

The invention belongs to the technical field of gas sensors, and particularly discloses a gas sensing device based on a thin film field effect transistor and a preparation method of the gas sensing device. According to the gas sensing device, a gate insulating layer, a channel active layer and a source / drain layer are sequentially and vertically stacked on a substrate, the source / drain layer comprises a source electrode and a drain electrode which are arranged at different positions in the horizontal direction and are insulated from each other, and the source electrode serves as the output end of the gas sensing device; the source / drain layer is sequentially provided with a gas-sensitive film which is located between the projections of the source electrode and the drain electrode in the horizontal direction and is isolated from the source electrode and the drain electrode through a medium, and the gas-sensitive film is located between the projections of the source electrode and the drain electrode in the horizontal direction. And the top electrode is used as an input end of the gas sensing device, coincides with or partially coincides with the projection of the drain electrode in the horizontal direction, and is isolated from the gas sensitive film, the source electrode and the drain electrode through a medium.

Description

Technical Field

[0001] The present application belongs to the technical field of gas sensors, and more specifically, relates to a gas sensor device based on a thin film field effect transistor and a preparation method thereof. Background Art

[0002] With the rise of new generation technologies such as the Internet of Things, big data, and artificial intelligence, the development of information technology will continue to show a trend of miniaturization, integration, intelligence, and marginalization. Sensors are important devices for people to obtain external information. The demand for gas detection in industrial testing, environmental monitoring, medical and health care, home monitoring, and other scenarios is constantly upgrading, and the demand for reliable, miniaturized, chip-level, and ultra-low power consumption gas monitoring is becoming increasingly urgent.

[0003] Most traditional gas sensors are two-terminal resistor gas sensors or three-terminal transistor types, which can only collect changes in resistance or analog current caused by changes in gas concentration, and then transmit this analog current to an external circuit unit for analog-to-digital conversion signal processing. They usually require high hardware costs, large size, and high power consumption. Therefore, when chip-based, it is usually necessary to design a dedicated signal processing circuit for on-chip analog-to-digital conversion processing. At the same time, semiconductor gas sensors based on three-terminal transistors and analog-to-digital conversion circuits containing multiple transistor structures are difficult to integrate on a large scale, which is not conducive to improving integration and reducing power consumption. Traditional semiconductor gas sensors combined with signal processing circuits require dozens of transistors to realize the functions of gas identification and analog-to-digital signal conversion.

[0004] Patent document CN108447915A discloses a thin film field effect transistor type gas sensor and a preparation method thereof; the thin film field effect transistor type gas sensor can be a thin film field effect transistor with a bottom gate top contact structure; the thin film field effect transistor includes a substrate, a gate insulating layer, and a channel active layer from bottom to top, thereby constituting a thin film field effect transistor; the transistor outputs an analog current signal, which needs to be subsequently connected to an analog-to-digital conversion circuit such as a ring oscillator to realize the conversion from analog signal to digital signal. A simple ring oscillator can be cascaded by 7 to 8 differential circuits, each differential circuit is composed of 4 to 5 transistors, and the entire analog-to-digital conversion circuit is composed of at least dozens of transistors, so that the analog current signal output by the thin film field effect transistor can be converted into a digital current signal that can be processed by the back-end functional circuit.

[0005] The non-patent document "A Bio-Inspired Neuromorphic Sensory System (AdvancedIntelligent Systems, 22 May 2022)" introduces a neuromorphic gas sensing system, in which the gas sensing unit is composed of a TO sensor array, the analog-to-digital signal processing unit is composed of a memristor composed of a Pt / Ag / TaOx / Pt structure, and a comparator unit is composed of a MOS tube. Its structure is shown in Figure b on page 2 and Figure a on page 4, where the comparator unit needs to be composed of multiple transistors. At the same time, the TO sensor is different from the field-effect transistor sensor, cannot be prepared using a silicon-based process, and cannot be monolithically integrated with the memristor, resulting in the separation of the sensing unit and the analog-to-digital conversion unit.

[0006] The document "Single Transistor Optoelectronic Spiking Neuron with Optogenetics- Inspired Spatiotemporal Dynamics (Advanced Functional Materials, February 202434 (22))" introduces a photoelectric pulse neuron, which is integrated with a grating-controlled MoS2 field-effect transistor and a threshold switch. Its structure is shown in Figure a on page 3. Since light is directly absorbed by MoS2, the MoS2 channel carrier concentration is changed by photogenerated carriers. Combined with the bottom gate voltage regulation, the output result reflects the two states of whether there is light or not. It can only indicate whether there is a signal, but cannot determine more specific intensity information. Summary of the invention

[0007] In view of the defects of the prior art, the purpose of the present application is to provide a gas sensor device based on a thin film field effect transistor and a preparation method thereof, in which a threshold switch structure is integrated in the gas sensor device to directly realize the conversion of the gas concentration signal into a pulse output signal.

[0008] The present application provides a gas sensor device based on a thin film field effect transistor, comprising a gate insulating layer, a channel active layer and a source / drain layer stacked in sequence on a substrate, wherein the source / drain layer comprises a source electrode and a drain electrode which are arranged at different positions in a horizontal direction and insulated from each other, the source electrode serves as an output end of the gas sensor device, and the channel active layer adopts a metal oxide semiconductor material or a low-dimensional semiconductor material; On the source / drain layer are arranged in sequence: The gas-sensitive film is located between the projections of the source electrode and the drain electrode in the horizontal direction and is isolated from the source electrode and the drain electrode by a dielectric; The top electrode, serving as the input terminal of the gas sensor device, overlaps or partially overlaps with the horizontal projection of the drain electrode, and is isolated from the gas sensitive film, the source electrode and the drain electrode by a dielectric.

[0009] Preferably, the channel active layer uses a semiconductor material with a relatively low resistivity; the metal oxide semiconductor material is preferably zinc oxide (ZnO) or indium gallium zinc oxide (IGZO); and the low-dimensional semiconductor material is preferably MoS2, carbon nanotubes, black phosphorus, metal organic framework compounds or Mxene.

[0010] Preferably, the top electrode is composed of a lower silver electrode and an upper protective metal layer, and the material of the upper protective metal layer is Au or Pt.

[0011] Preferably, the material of the gas-sensitive film is CeO2, WO3, or PbS.

[0012] Preferably, the material of the medium is Al2O3, HfO2 or h-BN.

[0013] Preferably, a vertical distance between the top electrode and the drain electrode, and a vertical distance between the gas-sensitive film and the channel active layer are both 8 nm to 12 nm.

[0014] Preferably, the gas sensor device further includes a gate electrode which is disposed on the substrate and is separated from other structures.

[0015] The present application also discloses a method for preparing the above-mentioned gas sensor device, comprising: sequentially preparing a gate insulating layer, a channel active layer, a source / drain layer, a dielectric, a top electrode and a gas-sensitive film.

[0016] In general, the above technical solutions conceived by this application have the following technical advantages compared with the prior art: 1. The gas sensor device disclosed in the present application realizes the gas sensing function, and the substrate, gate insulating layer, drain electrode, dielectric, and top electrode also constitute a threshold switch structure, which can realize analog-to-digital conversion in the same device and directly convert the gas concentration signal of the gas sensor device into a digital signal output; 2. The dielectric material is made of metal oxide or van der Waals insulating dielectric material, which insulates the gas-sensitive film from the source electrode and the drain electrode, and serves as a dielectric between the top electrode and the drain electrode, so that the gas sensor device can play a gas identification role; the reuse of the dielectric structure replaces the analog-to-digital conversion circuit composed of multiple MOS tubes, and the analog-to-digital conversion circuit function that can only be realized by a ring oscillator composed of dozens of transistors is realized by a gas sensor device, so that the integration is improved, and at the same time, the excess energy consumption that may be caused by multiple MOS tubes is reduced; it has been verified that the gas sensor device of the present application can reach a scale of 100μm, and is even expected to reach the nm scale under silicon-based technology; 3. The present application uses a channel active layer, a gas-sensitive film and a medium therebetween to form a gas-sensitive structure. By adjusting the materials and other parameters of the channel active layer and the gas-sensitive film, the output amplitude of the gas sensor device can be made more variable, making it more sensitive to changes in the concentration of the target gas, thereby achieving a sensitivity enhancement effect; 4. The gas sensor device of this application provides a feasible method for hierarchical design of pulse electronic devices, expands the application scope of neuromorphic hardware in the emerging field of bionic olfaction, and is expected to realize the integration of neuromorphic vision chips. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a schematic diagram of the structure of the gas sensor device provided in Example 1 of the present application; Figure 2 This is the preparation step of the gas sensor device provided in Example 1 of the present application; Figure 3 is a schematic diagram of the structure of Example 2 of the present application; Figure 4 It is the response characteristic diagram of the comparative example of the present application to different concentrations of NO2; Figure 5 is a response characteristic diagram of Example 2 of the present application to different concentrations of NO2; Figure 6 is a threshold switch pulse rectification characteristic diagram of Example 2 of the present application; Among them, the same figure marks represent the same structure from beginning to end, wherein, 1-substrate, 2-gate insulating layer, 3-source electrode, 4-channel active layer, 5-drain electrode, 6-dielectric layer, 7-lower silver electrode, 8-gas-sensitive thin film layer, 9-gate electrode, 10-upper protective metal. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0019] In the description of the present application, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the feature. In the description of the present application, "plurality" means two or more, unless otherwise clearly and specifically defined.

[0020] In addition, references throughout this specification to "one embodiment"; "one embodiment", "an example" or similar language indicate that a particular feature, structure, or characteristic described in conjunction with the embodiment is included in at least one embodiment of the present application. Thus, appearances of the phrase "in one embodiment"; "in one embodiment" and similar language throughout this specification may, but do not necessarily, all refer to the same embodiment.

[0021] Figure 1 This is a schematic diagram of the structure of the gas sensor device provided in the present application. As shown in the figure, a gate insulating layer 2, a channel active layer 4, a source / drain layer, a gas sensitive film 8, and a top electrode are vertically stacked in sequence on a substrate 1; a gate electrode 9 is also provided on one side of the substrate separated from other structures.

[0022] The channel active layer 4 is usually made of semiconductor materials, such as one-dimensional materials such as carbon nanotubes, two-dimensional materials such as molybdenum disulfide, black phosphorus, Mxene, organic semiconductor films with conductive ability, metal organic framework compounds (MOFs), metal oxide IGZO (indium gallium zinc oxide), etc.; the use of conductive semiconductor materials makes the current value of the gas sensor device have the dual regulation function of being affected by the bottom gate voltage and the change of the top gate voltage caused by the adsorption of gas by the gas sensitive film. Under the condition of fixed bottom gate voltage, the sensor current value will change with the gas concentration.

[0023] The source / drain layer includes a source electrode 3 and a drain electrode 5 at different positions in the horizontal direction, which are isolated by a dielectric 6; the material of the dielectric 6 is Al2O3, hexagonal boron nitride (h-BN) or HfO2, etc.; The gas-sensitive film 8 is arranged above the source / drain layer, between the projections of the source electrode 3 and the drain electrode 5 in the horizontal direction. It can be seen from the figure that the horizontal position corresponding to the source electrode 3 and the drain electrode 5 at the same horizontal position is also the medium 6; the thickness of the gas-sensitive film 8 is usually less than 100nm, and can be made of semiconductor gas-sensitive materials, including metal oxide semiconductors, two-dimensional layered materials, organic semiconductors, metal organic framework materials and colloidal quantum dots; in some embodiments, when the target gas is NO2 or NO, the material of the gas-sensitive film 8 can be PbS; when the target gas is H2S, the material of the gas-sensitive film 8 can be CeO2; when the target gas is NH3, the material of the gas-sensitive film 8 can be WO3; The top electrode is composed of a lower silver electrode 7 and an upper protective metal 10, and overlaps or partially overlaps with the projection of the drain electrode 5 in the horizontal direction; under the influence of voltage, the lower silver electrode 7 will extend a conductive wire toward the drain electrode 5, so that the insulation state between the two changes to a conductive state; the material of the upper protective metal 10 is Au or Pt; from Figure 1 It can be seen that the top electrode, the gas-sensitive film 8, the source electrode 3 and the drain electrode 5 are all isolated from each other by the dielectric 6; since the thickness of the dielectric has an influence on the elongated connection state of the conductive filament, the vertical spacing between the top electrode and the drain electrode, and the thickness of the dielectric between the gas-sensitive film and the channel active layer are all 8 nm to 12 nm.

[0024] In the gas sensor device of the present application, the substrate 1, the gate insulating layer 2, the source electrode 3, the channel active layer 4, the dielectric 6, the gas sensitive film 8 and the gate electrode 9 constitute a gas sensing structure; the substrate 1, the gate insulating layer 2, the drain electrode 5, the dielectric 6, and the top electrode constitute a threshold switch structure with a neuron integral pulse output function; the gas sensing structure and the threshold switch structure are integrated together through the dielectric layer, so that the gas sensor device of the present application has the integral emission function of a neuron and can convert the concentration value of the target gas into an output pulse signal.

[0025] The specific working process of the gas sensor device is as follows: Under working conditions, the drain electrode 5 is connected to nothing, the source electrode 3 is connected to the output, and the top electrode layer 7 acts as a threshold switch and an equivalent drain electrode for applying a pulse voltage; When the target gas does not exist (i.e., the gas does not react with the gas-sensitive film), the Ag at the bottom of the top electrode layer 7 will produce Ag conductive filaments under the action of voltage, which pass through the dielectric 6 and contact the drain electrode 5, so that the gas sensor device becomes conductive, and the current increases sharply from the gentle level, usually from the pA level to the μA level; after the rapid discharge is completed, the Ag conductive filament breaks, and the drain electrode 5 and the top electrode layer 7 are in an insulating state again; this cycle repeats, thereby generating a pulse voltage; in the above case, the growth rate of the Ag conductive filament is only affected by the pulse voltage frequency and amplitude of the top electrode layer 7. When the target gas exists, the conductivity of the gas-sensitive film changes, which causes the voltage between the top electrode 7 and the drain electrode 5 to change, and the growth rate of the Ag conductive filament changes, so that the output pulse frequency changes; the concentration of the corresponding gas to be measured can be determined by the pulse frequency.

[0026] In the above process, the target gas is identified through the gas-sensitive film; changing the charge distribution of the gas-sensitive film and the gas-sensitive gate voltage can affect the growth and breaking speed of the Ag conductive filament in the threshold switch, change the pulse output current, and convert the concentration information of the target gas into pulse current output information. This is equivalent to realizing analog-to-digital signal conversion with a single transistor, without the need for an analog-to-digital conversion circuit, and effectively improves the integration of gas sensor devices.

[0027] The gas sensor device disclosed in this application can be prepared by conventional semiconductor technology or silicon technology. Figure 2 This is a flow chart of a typical preparation method, in which the preparation sequence is: gate insulating layer, channel active layer, source / drain layer, dielectric, top electrode and gas sensitive film; however, the actual preparation process and preparation technology are not limited thereto; Figure 2 The specific preparation method of the embodiment shown is: S1 (content a): prepare a heavily doped silicon substrate 1, and the SiO2 on its surface is used as a gate insulating layer 2; plasma etches a rectangular groove on the surface SiO2 layer 2 to expose the lower silicon substrate 1; S2 (content b): electron beam evaporation deposits a gate electrode 9 on the exposed silicon substrate 1; S3 (content c): deposits or transfers the channel active layer 4 material on the part with the SiO2 layer 2; S4 (content d): electron beam lithography leads out a source electrode 3 and a drain electrode 5 on the channel material; S5 (content e): deposits or transfers a medium 6 on the device surface; S6 (content f) electron beam lithography patterning leads out a conductive wire pattern on the drain side, and deposits an Ag electrode 7 and an upper protective metal 10; S7 (content g): spin coating, drop coating or spray printing of nanoparticles to make a gas-sensitive film 8, and the specific film formation method of the gas-sensitive material depends on the characteristics of the material.

[0028] The following are examples: Example 1 Figure 1 This is a schematic diagram of the structure of the gas sensor device of this application. The overall size of the sensor is 250×200μm 2 , using Al2O3 as the dielectric layer, the preparation process includes the following steps: S1. Using heavily doped semiconductor wafer silicon as substrate 1 and gate insulating layer 2; S2. Maskless photolithography patterning of bottom gate electrode 9. The function of the bottom gate electrode is to be contacted by the needle tip of the probe station and add gate voltage. The shape of the bottom gate electrode is rectangular, 1000 μm long and 500 μm wide. The bottom gate dielectric oxide layer at the edge of the silicon wafer is etched away by plasma etching to expose the semiconductor wafer substrate. The bottom gate electrode metal (Cr (10 nm) / Au (60 nm)) is composited by electron beam evaporation. The gate electrode structure only needs to be conductive. S3. The channel active layer 4 is an active channel layer (30 nm thick) formed by a mechanical exfoliation method using a two-dimensional semiconductor thin film material MoS2. The length of the mechanically exfoliated few-layer MoS2 is 75 μm and the width is usually 40 μm. S4. The source electrode 3 and the drain electrode 5 are prepared by electron beam lithography and electron beam evaporation, both of which use a Cr / Au 5nm / 30nm structure; S5. Atomic layer deposition to prepare Al2O3 (11 nm) as dielectric layer 6; S6. 15nm Ag and 20nm Au electrodes 7 are sequentially deposited directly above the drain electrode 5 as conductive wire materials, and the Au electrode is only used as a protective layer 10 for the Ag conductive wire; S7. The gas-sensitive film 8 is prepared by a solution method using PbS quantum dots (film thickness 17 nm), and is composited on the dielectric layer 6 of the channel active layer 4 by drop coating, thereby forming a thin film field effect transistor gas sensor.

[0029] Example 2 Example 1 was repeated with the same steps, except that The dimensions of the channel active layer 4 are 60 μm long, 50 μm wide and 20 nm thick; the material of the medium 6 is h-BN, 70 μm long, 60 μm wide and 10 nm thick; the top electrode includes Ag10 nm and Au30 nm; the thickness of the gas sensitive film is 20 nm; its overall structure is as follows Figure 3 shown.

[0030] Comparative Example Example 2 was repeated with the same steps, except that step S5 was not performed, thereby obtaining a gas sensing device without a dielectric layer.

[0031] Verification Example 1 Test method of prepared thin film field effect transistor gas sensor The gas sensor prepared in Example 2 is electrically connected to the source, drain and gate metal connections of the device in turn according to the three probes of the probe station. The bottom gate voltage is in the range of -5V to 5V. The specific value selection will be affected by the preparation process deviation and the thickness of the two-dimensional channel material. The drain voltage is selected between 1V and 10V, and the source is grounded, that is, the source-drain voltage value depends on the thickness of the dielectric layer and the quality of the film, and the pulse frequency is within 100Hz-1KHz. Figure 4 The response characteristics of the gas sensor of comparative example 1 to different concentrations of NO2 are shown in FIG. Figure 4 Content (a) is the I / V characteristics of the sensor of comparative example 1 under air conditions. Only the voltage is applied to the drain to test the source-drain channel current. The current changes approximately linearly with the voltage, indicating that the channel is turned on and the channel layer functions well. Content (d) is the I / V characteristics of the transistor without adding gas. d / Vd Output characteristic curve. The current value under the same drain voltage changes significantly with the change of the bottom gate voltage, indicating that it is well regulated by the bottom gate voltage. Content (b) is the I / V characteristics under different NO2 gas concentrations. At this time, no bottom gate voltage is applied. The current decreases with the increase of gas concentration, indicating that it is regulated by the top gate voltage of the gas. However, it can be seen that when the gas concentration is between 0.2ppm and 5ppm, the change of the current value is very small, and the current value curves are close to overlap, which is not conducive to distinguishing gases. Content (e) is the I / V characteristics under different NO2 gas concentrations when the bottom gate voltage is applied and the gas concentration is changed while keeping the drain voltage at 0.5V. d / V g The output current value is between 0 and 5 μA when the gas concentration is from 0.1 ppm to 5 ppm, and the discrimination is also low. Content (c) and content (f) are the I d / V g Compared with the curve in content (e), it can be seen that with the increase of drain voltage, the output under the same gas concentration and the same gate voltage increases slightly. When the drain voltage in content (c) increases from 0.5V in content (e) to 1V, only the gas with a concentration of 0.1ppm reaches above 5μA and is less than 10μA, and the current values ​​of the other high-concentration gases are still below 5μA. Content (f) continues to increase the drain voltage to 5V. It can be seen that the current value of the gas with 0.1ppm increases to about 15μA, and the current value of the gas with 0.2ppm increases to about 10μA. The current value of the gas with higher concentration does not increase significantly and the output distribution is still relatively concentrated, indicating that the gas sensor has low sensitivity and discrimination to relatively high-concentration gases.

[0032] Figure 5 The response characteristics of the transistor gas sensor of Example 2 to different concentrations of NO2 are shown. Figure 5 Content (a) is the I / V characteristics of the sensor of Example 2 under air conditions. Only the voltage is applied to the drain to test the source-drain channel current. The current changes approximately linearly with the voltage, indicating that the channel is turned on and the channel layer functions well. Content (d) is the I / V characteristics of the transistor without adding gas. d / V d Output characteristic curve, the current value under the same drain voltage changes significantly with the change of bottom gate voltage, indicating that it is well regulated by the bottom gate voltage. Content (b) is the I / V characteristic under different NO2 gas concentrations. At this time, no bottom gate voltage is applied, and the current decreases with the increase of gas concentration, but Figure 4 Compared with the curve in content (b), the output curves of gases with different concentrations have obvious dispersion effects and the current values ​​corresponding to the concentrations become larger, indicating that the sensor has higher discrimination and sensitivity to gases with different concentrations, and the output current is more effectively regulated by the top gate voltage of the gas. Content (e) shows the I d / Vg From the curve, we can see that the gas concentration ranges from 0.1ppm to 5ppm, and the corresponding output current value ranges from 8uA to 0, showing an approximately uniform distribution. Figure 4 Content (e) shows that all gas concentrations are densely distributed below 5uA, and the discrimination effect is more significant. The output current value of the same concentration of gas at the same gate voltage also increases, showing a sensitivity enhancement effect. Content (c) and content (f) show the I d / V g The curve is compared with the content (e). It can be seen that as the drain voltage increases, the output current increases under the same gas concentration and the same gate voltage, and both show an effect of nearly uniform distribution. Figure 5 Content (c) and content (f) and Figure 4 Comparing contents (c) and (f), we can see that the current value distribution has increased and become more uniform. The larger current value makes the response to different gases more sensitive, and the more uniform current value distribution of gases with different concentrations makes the distinction between gases with different concentrations more accurate, especially for high-concentration gases. As the current value increases, the degree of distinction also increases, indicating that the dielectric layer improves the gas-sensitive performance of the thin-film field-effect transistor and has a sensitivity-enhancing effect.

[0033] Verification Example 2 Threshold Switch Rectification Characteristics Figure 6 It is the threshold switch pulse rectification characteristic diagram of Example 2; the black curve shows the rectification characteristics of the threshold switch under air conditions with a drain voltage of 1V, the source grounded, and no bottom gate voltage, the input DC voltage, and the output current in the form of a pulse square wave. Among them, the red curve shows the pulse square wave caused by NO2 diluted to a concentration of 0.1ppm with nitrogen under a drain voltage of 1V without a bottom gate voltage. It can be seen that the changes in pulse width and amplitude compared with air. It can be seen that the olfactory sensor is significantly regulated by the top gate pressure caused by the gas concentration of the bottom gate pressure. At the same time, the threshold switch has an integral rectification characteristic, and the drain pulse input will be re-rectified into a new pulse output. When the drain input is fixed, the new pulse frequency is regulated by the top gate and bottom gate voltages, and the bottom gate voltage is fixed, so that the gas concentration affects the top gate voltage, changes the output current frequency of the threshold switch, and completes the pulse output current.

[0034] The same test was carried out on Example 1, and it was found that the same effect as Example 2 was also achieved, indicating that when the dielectric layer is Al2O3, it can also provide physical space for the growth and break of the Ag filament, and at the same time, the pulse output effect can be achieved by immediately disconnecting after the discharge is turned on, which proves the scalability of the design.

[0035] At the device level, the threshold switch field effect transistor gas sensor based on the three-terminal electrical structure of the embodiment of the present application has the characteristics that the amplitude and frequency of the pulse output current are adjustable with the gas concentration. Under the conditions of the same bottom gate voltage and input drain pulse voltage, gas identification and pulse signal output can be achieved through a single device, thereby having compact gas sensing and signal processing functions, solving the problem of low integration of analog-to-digital conversion circuits, and more importantly, the device structure provides a feasible method for highly scalable and hierarchical design of pulse electronic devices, expanding the application scope of neuromorphic hardware in the emerging field of bionic olfaction, and is expected to realize the integration of neuromorphic vision chips. At the future application level, neuromorphic olfactory sensors based on field effect transistor structures are easy to integrate in large-scale arrays, and will also be easy to integrate future application algorithms and edge computing. They have ultra-compact physical structures and can be used as core components of large-scale neuromorphic olfactory chips.

[0036] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims

1. A gas sensor device based on a thin film field effect transistor, comprising a gate insulating layer, a channel active layer and a source / drain layer stacked in sequence on a substrate, wherein the source / drain layer comprises a source electrode and a drain electrode which are arranged at different positions in a horizontal direction and insulated from each other, and the source electrode serves as an output end of the gas sensor device, characterized in that: The channel active layer is made of metal oxide semiconductor material or low-dimensional semiconductor material; On the source / drain layer are arranged in sequence: The gas-sensitive film is located between the projections of the source electrode and the drain electrode in the horizontal direction and is isolated from the source electrode and the drain electrode by a dielectric; The top electrode, serving as the input terminal of the gas sensor device, overlaps or partially overlaps with the horizontal projection of the drain electrode, and is isolated from the gas sensitive film, the source electrode and the drain electrode by a dielectric.

2. The gas sensor device according to claim 1, characterized in that: The metal oxide semiconductor material is zinc oxide or indium gallium zinc oxide, and the low-dimensional semiconductor material is MoS2, carbon nanotubes, black phosphorus, metal organic framework compounds or Mxene.

3. The gas sensor device according to claim 1, characterized in that: The top electrode is composed of a lower silver electrode and an upper protective metal layer, and the material of the upper protective metal layer is Au or Pt.

4. The gas sensor device according to claim 1, characterized in that: The materials of the gas-sensitive film are CeO2, WO3 and PbS.

5. The gas sensor device according to claim 1, characterized in that: The material of the medium is Al2O3, HfO2 or h-BN.

6. The gas sensor device according to claim 1, characterized in that: The vertical distance between the top electrode and the drain electrode, and the vertical distance between the gas-sensitive film and the channel active layer are 8nm to 12nm.

7. The gas sensor device according to claim 1, characterized in that: The invention also includes a gate electrode which is arranged on the substrate and separated from other structures.

8. A method for preparing the gas sensor device according to any one of claims 1 to 7.

9. The preparation method according to claim 8, characterized in that: include: The gate insulating layer, the channel active layer, the source / drain layer, the dielectric, the top electrode and the gas-sensitive film are prepared in sequence.

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