Gas sensor device based on thin film field effect transistor and method for manufacturing the same

Abstract

The application belongs to the technical field of gas sensor, and specifically discloses a gas sensor device based on a thin film field effect transistor and a preparation method thereof. The gas sensor device vertically and sequentially has a gate insulating layer, a channel active layer and a source / drain layer on a substrate. The source / drain layer includes a source electrode and a drain electrode arranged at different positions in the horizontal direction and insulated from each other. The source electrode serves as an output end of the gas sensor device. Above the source / drain layer, a gas sensitive thin film is arranged, which is located between the projections of the source electrode and the drain electrode in the horizontal direction and is insulated from the source electrode and the drain electrode through a medium. A top electrode serves as an input end of the gas sensor device, coincides or partially coincides with the projection of the drain electrode in the horizontal direction, and is insulated from the gas sensitive thin film, the source electrode and the drain electrode through a medium.

Description

Technical Field

[0001] This application belongs to the field of gas sensor technology, and more specifically, relates to a gas sensor device based on thin-film field-effect transistor and its fabrication method. Background Technology

[0002] With the rise of next-generation technologies such as the Internet of Things, big data, and artificial intelligence, the development of information technology will continue to show trends of miniaturization, integration, intelligence, and edge computing. Sensors are important devices for people to obtain information from the outside world. In scenarios such as industrial inspection, environmental monitoring, medical and health care, and home monitoring, the demand for gas detection is constantly upgrading, and the need for reliable, miniaturized, chip-level, and ultra-low power gas monitoring is becoming increasingly urgent.

[0003] Traditional gas sensors are mostly two-terminal resistive gas sensors or three-terminal transistor types, which can only detect changes in resistance or analog current caused by changes in gas concentration. This analog current is then transmitted to an external circuit unit for analog-to-digital conversion (ADC) signal processing. This typically requires high hardware costs, resulting in large size and high power consumption. Therefore, when implementing them on a chip, dedicated signal processing circuits are usually required for on-chip ADC processing. Furthermore, three-terminal transistor-based semiconductor gas sensors and ADC circuits containing multiple transistors are difficult to integrate on a large scale, hindering improvements in integration density and power consumption reduction. Traditional semiconductor gas sensors, combined with signal processing circuits, require dozens of transistors to achieve gas identification and ADC functionality.

[0004] Patent document CN108447915A discloses a thin-film field-effect transistor (TFT) gas sensor and its fabrication method. This TFT gas sensor can be a bottom-gate top-contact TFT structure. The TFT comprises, from bottom to top, a substrate, a gate insulating layer, and a channel active layer, thus forming a TFT. The transistor outputs an analog current signal, which needs to be connected to an analog-to-digital converter (ADC) circuit, such as one using a ring oscillator, to convert the analog signal to a digital signal. A simple ring oscillator can be composed of 7 to 8 cascaded differential circuits, each consisting of 4 to 5 transistors. The entire ADC circuit must consist of at least several dozen transistors to convert the analog current signal output by the TFT into a digital current signal that can be processed by the downstream functional circuitry.

[0005] The non-patent document "A Bio-Inspired Neuromorphic Sensory System (Advanced Intelligent Systems, 22 May 2022)" introduces a neuromorphic gas sensing system. The gas sensing unit consists of a TO sensor array, and the analog-to-digital signal processing unit consists of a memristor composed of a Pt / Ag / TaOx / Pt structure and a comparator unit composed of MOS transistors. Its structure is shown in Figure b on page 2 and Figure a on page 4. 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 and cannot be fabricated using silicon-based processes. It cannot be monolithically integrated with the memristor, resulting in the separation of the sensing unit and the analog-to-digital conversion unit.

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

[0007] To address the shortcomings of existing technologies, the purpose of this application is to provide a gas sensor device based on thin-film field-effect transistors and its fabrication method. The gas sensor device integrates a threshold switch structure to directly convert gas concentration signals into pulse output signals.

[0008] This application provides a gas sensor based on a thin-film field-effect transistor, including a gate insulating layer, a channel active layer, and a source / drain layer sequentially stacked on a substrate. The source / drain layer includes a source electrode and a drain electrode disposed at different positions in the horizontal direction and insulated from each other. The source electrode serves as the output terminal of the gas sensor. The channel active layer is made of a metal oxide semiconductor material or a low-dimensional semiconductor material.

[0009] Above the source / drain layer, the following are also set in sequence:

[0010] A gas-sensitive thin film is located between the projections of the source electrode and the drain electrode in the horizontal direction, and is isolated from both the source electrode and the drain electrode by a dielectric.

[0011] The top electrode, which serves as the input terminal of the gas sensor, coincides or partially coincides 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.

[0012] Preferably, the active layer of the channel is made of a semiconductor material with low resistivity; the metal oxide semiconductor material is preferably zinc oxide (ZnO) or indium gallium zinc oxide (IGZO); the low-dimensional semiconductor material is preferably MoS2, carbon nanotubes, black phosphorus, metal-organic framework compounds or Mxene.

[0013] Preferably, the top electrode consists of a lower silver electrode and an upper protective metal, wherein the upper protective metal is made of Au or Pt.

[0014] Preferably, the material of the gas-sensitive film is CeO2, WO3, or PbS.

[0015] Preferably, the material of the medium is Al2O3, HfO2, or h-BN.

[0016] Preferably, the vertical spacing between the top electrode and the drain electrode, and the vertical spacing between the gas-sensitive film and the channel active layer are both 8 nm to 12 nm.

[0017] Preferably, the gas sensor further includes a gate electrode disposed on the substrate and separate from other structures.

[0018] This application also discloses a method for fabricating the above-mentioned gas sensor device, including: sequentially fabricating a gate insulating layer, a channel active layer, a source / drain layer, a dielectric, a top electrode, and a gas-sensitive thin film.

[0019] In summary, compared with the prior art, the technical solutions conceived in this application have the following main technical advantages:

[0020] 1. The gas sensor disclosed in this application, while realizing the gas sensing function, also forms a threshold switching structure with the substrate, gate insulating layer, drain electrode, dielectric, and top electrode, which can realize analog-to-digital conversion in the same device and directly convert the gas concentration signal of the gas sensor into a digital signal output.

[0021] 2. The dielectric material is a metal oxide or van der Waals insulating dielectric material, which insulates the gas-sensitive thin film from the source and drain electrodes while serving as a dielectric between the top and drain electrodes, enabling the gas sensor to perform gas identification. The reuse of the dielectric structure replaces the analog-to-digital converter circuit composed of multiple MOS transistors, realizing the analog-to-digital converter circuit function that previously required dozens of transistors in a ring oscillator, thus improving integration and reducing the unnecessary power consumption that might have been caused by multiple MOS transistors. It has been verified that the gas sensor of this application can reach the 100μm scale, and may even reach the nm scale under silicon-based processes.

[0022] 3. This application utilizes a channel active layer, a gas-sensitive thin film, and the medium between them to form a gas-sensitive structure. By adjusting the materials and other parameters of the channel active layer and the gas-sensitive thin film, the output amplitude of the gas sensor can be made to change more significantly, making it more sensitive to changes in the concentration of the target gas, thus achieving the effect of enhanced sensitivity.

[0023] 4. The gas sensor device of this application provides a feasible method for the layered design of pulsed 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. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the structure of the gas sensor device provided in Embodiment 1 of this application;

[0025] Figure 2 These are the fabrication steps of the gas sensor device provided in Embodiment 1 of this application;

[0026] Figure 3 This is a schematic diagram of the structure of Embodiment 2 of this application;

[0027] Figure 4 This is a comparative example of the response characteristics of this application to different concentrations of NO2;

[0028] Figure 5 This is a response characteristic diagram of Example 2 of this application to different concentrations of NO2;

[0029] Figure 6 This is a threshold switch pulse rectification characteristic diagram of Embodiment 2 of this application;

[0030] In this drawing, the same reference numerals represent the same structure throughout, including: 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, and 10-upper protective metal layer. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0032] In the description of this application, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0033] Furthermore, throughout this specification, references to "an embodiment"; "an embodiment," "an example," or similar language indicate that a particular feature, structure, or characteristic described in connection with that embodiment is included in at least one embodiment of this application. Therefore, the appearance of the phrase "in one embodiment;" throughout this specification, and similar language, may, but not necessarily, refer to the same embodiment.

[0034] Figure 1 This is a schematic diagram of the structure of the gas sensor device provided in this application. As shown in the figure, a gate insulating layer 2, a channel active layer 4, a source / drain layer, a gas-sensitive thin film 8, and a top electrode are stacked vertically in sequence on the substrate 1; a gate electrode 9 is also provided on the side of the substrate that is separated from other structures.

[0035] The active layer 4 of the channel is usually made of semiconductor materials, such as one-dimensional materials like carbon nanotubes, two-dimensional materials like molybdenum disulfide, black phosphorus, and Mxene, conductive organic semiconductor thin films, metal-organic frameworks (MOFs), and metal oxides IGZO (indium gallium zinc oxide). By using conductive semiconductor materials, the current value of the gas sensor can be dually regulated by the change in the bottom gate voltage and the top gate voltage caused by the adsorption of gas by the gas-sensitive thin film. With a fixed bottom gate voltage, the sensor current value will follow the change in gas concentration.

[0036] The source / drain layer includes a source electrode 3 and a drain electrode 5 at different positions in the horizontal direction, which are isolated from each other by a dielectric 6; the material of the dielectric 6 is Al2O3, hexagonal boron nitride (h-BN) or HfO2, etc.

[0037] A gas-sensitive thin film 8 is disposed above the source / drain layer, in the region between the horizontal projections of the source electrode 3 and the drain electrode 5. As can be seen from the figure, the region corresponding to the horizontal direction of the source electrode 3 and the drain electrode 5 at the same horizontal position is also a dielectric 6. The thickness of the gas-sensitive thin film 8 is typically less than 100 nm, and it 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 thin film 8 can be PbS; when the target gas is H2S, the material of the gas-sensitive thin film 8 can be CeO2; when the target gas is NH3, the material of the gas-sensitive thin film 8 can be WO3.

[0038] The top electrode consists of a lower silver electrode 7 and an upper protective metal 10, which coincides or partially coincides with the horizontal projection of the drain electrode 5. Under the influence of voltage, the lower silver electrode 7 will extend a conductive wire towards the drain electrode 5, so that the two are changed from an insulating state to a conductive state. The material of the upper protective metal 10 is Au or Pt.

[0039] from Figure 1 As can be seen, the top electrode, the gas-sensitive film 8, the source electrode 3, and the drain electrode 5 are all isolated from each other by a dielectric 6. Since the thickness of the dielectric affects the elongation connection state of the conductive wire, the vertical distance between the top electrode and the drain electrode, as well as the thickness of the dielectric between the gas-sensitive film and the channel active layer, are all 8 nm to 12 nm.

[0040] In the gas sensor device of this application, the substrate 1, gate insulating layer 2, source electrode 3, channel active layer 4, dielectric 6, gas-sensitive thin film 8 and gate electrode 9 constitute a gas sensing structure; the substrate 1, gate insulating layer 2, drain electrode 5, dielectric 6 and top electrode constitute a threshold switch structure with 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 this application has the integral emission function of a neuron, which can convert the concentration value of the target gas into an output pulse signal.

[0041] The specific working process of this gas sensor is as follows:

[0042] Under operating conditions, drain electrode 5 is unconnected, source electrode 3 is connected to the output, and top electrode layer 7 serves as both a threshold switch and an equivalent drain for applying pulse voltage.

[0043] When the target gas is absent (i.e., the gas does not react with the gas-sensitive film), Ag at the bottom of the top electrode layer 7 will generate Ag conductive filaments under voltage, passing through the dielectric 6 and contacting the drain electrode 5, making the gas sensor conductive. The current will increase sharply from a gradual level, typically from the pA to the μA level. After rapid discharge, the Ag conductive filaments break, and the drain electrode 5 and the top electrode layer 7 will be in an insulating state again. This cycle repeats, generating a pulse voltage. In the above case, the growth rate of the Ag conductive filaments is only affected by the frequency and amplitude of the pulse voltage of the top electrode layer 7. When the target gas is present, the conductivity of the gas-sensitive film changes, causing a change in the voltage between the top electrode 7 and the drain electrode 5, altering the growth rate of the Ag conductive filaments, and thus changing the output pulse frequency. The concentration of the corresponding analyte gas can be determined by the pulse frequency.

[0044] In the above process, the target gas is identified through the gas-sensitive thin film. Changing the charge distribution of the gas-sensitive thin film and altering the gas-sensitive gate voltage can affect the growth and breakage rate of the Ag conductive wire in the threshold switch, thereby changing the pulse output current and converting the concentration information of the target gas into pulse current output information. This is equivalent to a single transistor achieving analog-to-digital signal conversion, eliminating the need for an analog-to-digital conversion circuit and effectively improving the integration of the gas sensor.

[0045] The gas sensor disclosed in this application can be fabricated using conventional semiconductor processes or silicon processes. Figure 2 The flowchart illustrates a typical embodiment of the fabrication method, in which the fabrication sequence is: gate insulating layer, channel active layer, source / drain layer, dielectric, top electrode, and gas-sensitive thin film; however, the actual fabrication process and technology are not limited to this. Figure 2 The specific preparation method of the embodiment shown is as follows: S1 (content a): Prepare a heavily doped silicon substrate 1, with SiO2 on its surface as a gate insulating layer 2; etch a rectangular groove on the SiO2 layer 2 on the surface using plasma to expose the lower silicon substrate 1; S2 (content b): deposit a gate electrode 9 by electron beam evaporation at the exposed silicon substrate 1; S3 (content c): deposit or transfer the channel active layer 4 material at the location with the SiO2 layer 2; S4 (content d): draw out the source electrode 3 and drain electrode 5 on the channel material by electron beam photolithography; S5 (content e): deposit or transfer a dielectric 6 on the device surface; S6 (content f): pattern a conductive wire pattern on the drain side by electron beam photolithography, and deposit an Ag electrode 7 and an upper protective metal 10; S7 (content g): spin-coat, drop-coat, or spray-print nanoparticles to make a gas-sensitive thin film 8, the specific gas-sensitive material film formation method depending on the material characteristics.

[0046] The following is an example:

[0047] Example 1

[0048] Figure 1This is a schematic diagram 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:

[0049] S1. Heavy doped semiconductor wafer silicon is used as substrate 1 and gate insulating layer 2;

[0050] S2. Maskless photolithography patterned bottom gate electrode 9. The bottom gate electrode is designed to be contacted by the probe tip and subjected to gate voltage. It is rectangular with a length of 1000μm and a width of 500μm. The oxide layer of the bottom gate dielectric at the edge of the silicon wafer is etched away by plasma etching to expose the semiconductor wafer substrate. The bottom gate electrode metal (using Cr (10nm) / Au (60nm)) composite is deposited by a new electron beam evaporation. This gate electrode structure only needs to be conductive.

[0051] S3. The active channel layer 4 is an active channel layer (thickness 30nm) formed by mechanical exfoliation of two-dimensional semiconductor thin film material MoS2. The length of the mechanically exfoliated few-layer MoS2 is 75μm and the width is usually 40μm.

[0052] S4. Source electrode 3 and drain electrode 5 were fabricated by electron beam lithography and new electron beam evaporation, respectively, both of which adopted a Cr / Au 5nm / 30nm structure;

[0053] S5. Atomic layer deposition was used to prepare Al2O3 (11 nm) as the dielectric layer 6;

[0054] S6. Sequentially deposit 15nm Ag and 20nm Au electrodes 7 above the drain electrode 5 as conductive wire materials. The Au electrode is only used as a protective layer 10 for the Ag conductive wire.

[0055] S7. The gas-sensitive thin film 8 is prepared by solution method from PbS quantum dots (film thickness 17nm) 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.

[0056] Example 2

[0057] Repeat the same steps as in Example 1, except that,

[0058] The active layer 4 of the channel has dimensions of 60 μm in length, 50 μm in width, and 20 nm in thickness; the dielectric 6 is made of h-BN, with dimensions of 70 μm in length, 60 μm in width, and 10 nm in thickness; the top electrode comprises Ag 10 nm and Au 30 nm; the gas-sensitive thin film has a thickness of 20 nm; its overall structure is as follows. Figure 3 As shown.

[0059] Comparative Example

[0060] Example 2 was repeated with the same steps, except that step S5 was omitted, resulting in a gas sensor device without a dielectric layer.

[0061] Verification Example 1: Test Method for the Fabricated Thin-Film Field-Effect Transistor Gas Sensor

[0062] The gas sensor prepared in Example 2 is electrically connected to the source, drain, and gate of the device by sequentially connecting the three probes of the probe station to the device. The range of the bottom gate voltage is between -5V and 5V. The specific value will be affected by the deviation of the fabrication process and the thickness of the two-dimensional material of the channel. The drain voltage is selected between 1V and 10V. The source is grounded. That is, the source and drain voltage values ​​depend on the thickness of the dielectric layer and the quality of the thin film. The pulse frequency is within 100Hz-1KHz. Figure 4 To illustrate the response characteristics of the gas sensor in Comparative Example 1 to different concentrations of NO2, Figure 4 Content (a) shows the I / V characteristics of the sensor in Comparative Example 1 under air conditions. The source-drain channel current was measured by applying voltage only to the drain. The current changes approximately linearly with the voltage, indicating that the channel is conducting and the channel layer function is good. Content (d) shows the I / V characteristics of the transistor without gas. d / V d The output characteristic curves show that the current value at the same drain voltage changes significantly with the change of the bottom gate voltage, indicating good regulation by the bottom gate voltage. Content (b) shows the I / V characteristics under different NO2 gas concentrations. In this case, no bottom gate voltage is applied, and the current decreases with the increase of gas concentration, indicating regulation by the top gate voltage. However, it can be seen that when the gas concentration is between 0.2ppm and 5ppm, the change in current value is very small, and the current value curves almost overlap, which is not conducive to distinguishing gases. Content (e) shows the I / V characteristics under the condition of maintaining a drain voltage of 0.5V while applying a bottom gate voltage and changing the gas concentration. d / V g The curves show that the output current values ​​for gas concentrations ranging from 0.1 ppm to 5 ppm are all between 0 and 5 μA, exhibiting low discrimination. Contents (c) and (f) represent the I values ​​under varying drain voltage conditions. d / V g Comparing the curves with content (e), it can be seen that as the drain voltage increases, the output at the same gas concentration and gate voltage increases slightly. In content (c), when the drain voltage increases from 0.5V in content (e) to 1V, only the current value of the gas with a concentration of 0.1ppm reaches above 5μA and less than 10μA, while the current values ​​of other high-concentration gases are still below 5μA. In content (f), the drain voltage is further increased to 5V, and it can be seen that the current value of the gas with a concentration of 0.1ppm increases to about 15μA, and the current value of the gas with a concentration of 0.2ppm increases to about 10μA. The current value of the gas with a higher concentration does not increase significantly and the output distribution is still relatively concentrated, indicating that the gas sensor has low sensitivity and discrimination for high-concentration gases.

[0063] Figure 5 The response characteristics of the transistor gas sensor of Example 2 to different concentrations of NO2 are shown. Figure 5 Content (a) shows the I / V characteristics of the sensor in Example 2 under air conditions. The source-drain channel current was tested by applying voltage only to the drain. The current changes approximately linearly with the voltage, indicating that the channel is conducting and the channel layer function is good. Content (d) shows the I / V characteristics of the transistor without gas. d / V d The output characteristic curves show that the current value at the same drain voltage changes significantly with the gate voltage, indicating good regulation by the gate voltage. Content (b) shows the I / V characteristics under different NO2 gas concentrations. In this case, no gate voltage is applied, and the current decreases with increasing gas concentration, but... Figure 4 Compared to the curve in content (b), the output curves for different gas concentrations show a significant dispersion effect and the corresponding current values ​​increase, indicating that the sensor's discrimination and sensitivity to different gas concentrations are higher, and the output current is better controlled by the gas top gate voltage. Content (e) shows the I under the condition of maintaining a drain voltage of 0.5V while simultaneously applying a bottom gate voltage and changing the gas concentration. d / V g The curve shows that as the gas concentration increases from 0.1 ppm to 5 ppm, the corresponding output current value decreases from 8 μA to 0, exhibiting an approximately uniform distribution. This is in contrast to... Figure 4 Content (e) shows a relatively dense distribution of all gas concentrations below 5uA, resulting in more significant differentiation. Furthermore, the output current for gases of the same concentration at the same gate voltage also increases, demonstrating a sensitizing effect. Contents (c) and (f) show I under conditions of increased drain voltage. d / V g As shown in the curve and compared with content (e), it can be seen that as the leakage voltage increases, the output current under the same gas concentration and the same gate voltage increases, and both exhibit an approximately uniform distribution. Figure 5 Content (c) and Content (f) with Figure 4 A comparison of contents (c) and (f) shows that the current distribution has increased and become more uniform. The increased current makes the response to different gases more sensitive, and the more uniform distribution of current values ​​for different gas concentrations makes the distinction between different gas concentrations more accurate. In particular, for high-concentration gases, the distinction increases along with the increase in current value, indicating that the dielectric layer improves the gas-sensing performance of the thin-film field-effect transistor and has a sensitizing effect.

[0064] Verification Example 2: Threshold Switch Rectification Characteristics

[0065] Figure 6This is a pulse rectification characteristic diagram of the threshold switch in Example 2. The black curve shows the rectification characteristics of the threshold switch under air conditions with a 1V drain voltage, source grounded, and no bottom gate voltage applied. The input is DC voltage, and the output current is a pulsed square wave. The red curve shows the pulsed square wave caused by diluting NO2 to a concentration of 0.1ppm with nitrogen gas under 1V drain voltage and no bottom gate voltage. The pulse width and amplitude changes compared to air. It can be seen that the olfactory sensor is significantly affected by the top gate voltage due to the gas concentration at the bottom gate voltage. Simultaneously, the threshold switch has integral rectification characteristics; the drain pulse input is re-rectified into a new pulse output. With a fixed drain input, the new pulse frequency is controlled by the top and bottom gate voltages. With a fixed bottom gate voltage, the gas concentration affects the top gate voltage, changing the output current frequency of the threshold switch and completing the pulsed output current.

[0066] The same test was performed on Example 1, and the same effect as in Example 2 was found. This shows that when the dielectric layer is Al2O3, it can also provide physical space for the growth and breakage of Ag filaments. At the same time, it can immediately disconnect after conduction and discharge to achieve the effect of pulse output, which proves the scalability of the design.

[0067] At the device level, the threshold-switching field-effect transistor gas sensor based on a three-terminal electrical structure features adjustable pulse output current amplitude and frequency according to gas concentration. Under the same gate voltage and input drain pulse voltage, gas identification and pulse signal output can be achieved through a single device, thus possessing compact gas sensing and signal processing functions. This solves the problem of low integration density in analog-to-digital conversion circuits. More importantly, this device structure provides a feasible method for highly scalable and hierarchical design of pulse electronics, expanding the application scope of neuromorphic hardware in the emerging field of bionic olfaction and potentially enabling the integration of neuromorphic vision chips. In terms of future applications, neuromorphic olfactory sensors based on field-effect transistor structures are easy to integrate into large-scale arrays and will also be easy to integrate with future application algorithms and edge computing. With an ultra-compact physical structure, they can serve as core components of large-scale neuromorphic olfactory chips.

[0068] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A thin film field effect transistor-based gas sensor device comprising a gate insulating layer, a channel active layer, and a source / drain layer, which are sequentially stacked on a substrate, the source / drain layer comprising a source electrode and a drain electrode, which are disposed at different positions in a horizontal direction and insulated from each other, the source electrode serving as an output terminal of the gas sensor device, characterized in that, The channel active layer adopts metal oxide semiconductor material or low-dimensional semiconductor material; Further arranged on the source / drain layer are: A gas sensitive thin film, located between the horizontal projection of the source electrode and the drain electrode, and separated from the source electrode and the drain electrode by a medium; A top electrode, as the input terminal of the gas sensing device, coinciding or partially coinciding with the horizontal projection of the drain electrode, and separated from the gas sensitive thin film, the source electrode and the drain electrode by a medium.

2. The gas sensing device according to claim 1, wherein The metal oxide semiconductor material is zinc oxide or indium gallium zinc oxide, and the low-dimensional semiconductor material is MoS2, carbon nanotube, black phosphorus, metal organic framework compound or Mxene.

3. The gas sensing device of claim 1, wherein The top electrode is composed of a lower silver electrode and an upper protective metal, and the material of the upper protective metal is Au or Pt.

4. The gas sensing device of claim 1, wherein The material of the gas sensitive thin film is CeO2, WO3 or PbS.

5. The gas sensing device of claim 1, wherein The material of the medium is Al2O3, HfO2 or h-BN.

6. The gas sensing device of claim 1, wherein, The vertical distance between the top electrode and the drain electrode, and the vertical distance between the gas sensitive thin film and the channel active layer are 8-12 nm.

7. The gas sensing device of claim 1, wherein Further comprising a gate electrode arranged on the substrate and separated from other structures.

8. A preparation method of the gas sensing device according to any one of claims 1-7.

9. The production method according to claim 8, wherein Comprise: Sequentially preparing a gate insulating layer, a channel active layer, a source / drain layer, a medium, a top electrode and a gas sensitive thin film.

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