Specific gas coding method based on gas sensitive field effect transistor and application

Abstract

The invention belongs to the field of gas sensors, and particularly discloses a specific gas coding method based on a gas sensitive field effect transistor and application. The specific gas coding method comprises the following steps: obtaining a receptor function factor # imgabs0 # and a conversion function factor # imgabs1 # as characteristic points of gas so as to realize specific gas coding; wherein # imgabs2 is the surface potential variation of a gas-sensitive film in the gas-sensitive field effect transistor, n is the number of gas molecules in unit volume, mgas is the mass of the gas molecules, delta I is the current variation of the gas-sensitive field effect transistor, b1 is a constant related to temperature, and b2 is a constant related to an electrode channel of the gas-sensitive field effect transistor. According to the application, the electronic transduction process generated by gas-solid interaction is analyzed by utilizing the advantage that the electrical parameters of the field effect transistor gas sensor can be extracted, so that different gases can be distinguished.

Description

Technical Field

[0001] The present application belongs to the technical field of gas sensors, and more specifically, to a specific gas encoding method and application based on a gas-sensitive field effect transistor. Background Art

[0002] As an important part of artificial intelligence perception technology, semiconductor gas sensors have greatly expanded our ability to obtain gas information in the objective world, enabling us to effectively deal with the potential threats of colorless, odorless, toxic and harmful, as well as flammable and explosive gases. At the same time, they show great application potential in medical fields such as respiratory diagnosis and olfactory disorder treatment. However, traditional semiconductor gas sensors have the problems of broad spectrum response and insufficient specificity when identifying gases. To solve this problem, bio-inspired machine olfactory systems such as electronic noses have emerged. This type of system uses a series of semiconductor gas sensors to simulate the olfactory receptor cells of mammals, combined with advanced pattern recognition algorithms, to achieve the recognition of various gases.

[0003] Compared with the widely used machine vision technology, the development of electronic nose technology is relatively lagging behind. Although commercial electronic noses have been applied in the food industry and agricultural fields, their gas coding ability is still affected by the cross-sensitivity problem of gas sensors, resulting in insufficient sensor specificity, which limits the application of electronic noses in high-precision and high-reliability gas identification and quantitative detection. Therefore, it is necessary to develop a new gas identification coding method to achieve intelligent identification of specific target gases. The semiconductor gas sensing device of the prior art has the characteristics of high detection sensitivity, fast response time, low preparation cost, and easy miniaturization to gas, and is suitable for preparing micro sensors, so it has become the focus of sensor research in recent years (Research Progress of Nanostructured Thin Film Gas Sensors, Physics, 2014, 43 (06): 364-372.) However, there are usually multiple types of gases corresponding to a gas-sensitive material, and there are problems such as cross-sensitivity to gas and insufficient specificity during detection. Summary of the invention

[0004] In view of the defects of the prior art, the purpose of this application is to provide a specific odor coding method and a gas identification method based on a gas-sensitive field-effect transistor, which utilizes the advantage of the extractable electrical parameters of the field-effect transistor gas sensor to analyze the electron transduction process generated by the gas-solid interaction, thereby encoding specific gases and further distinguishing different gases.

[0005] To achieve the above-mentioned purpose, the present application provides a specific gas coding method based on a gas-sensitive field effect transistor, comprising: obtaining a receptor function factor x and a conversion function factor y as characteristic points of the gas to achieve specific gas coding;

[0006] Among them, receptor function factor Transfer Function Factor is the surface potential change of the gas-sensitive film in the gas-sensitive field-effect transistor, n is the number of gas molecules per unit volume, m gas is the mass of the gas molecules, ΔI is the current change of the gas-sensing field-effect transistor, b1 is a constant related to temperature, and b2 is a constant related to the electrode channel of the gas-sensing field-effect transistor.

[0007] Preferably,

[0008] Where k0 is the Boltzmann constant, T is the Kelvin temperature, and m gas is the mass of the gas molecule, S is the cross-sectional area of ​​the electrode channel in the gas-sensitive field-effect transistor, and e is the basic charge.

[0009] Preferably, characteristic points of the gas at different concentrations are obtained, and a characteristic space of the gas is obtained based on the characteristic points.

[0010] Preferably, the material of the gas-sensitive thin film of the gas-sensitive field-effect transistor is quantum dots, two-dimensional materials or metal oxides.

[0011] The present application also discloses a gas identification method based on a gas-sensitive field effect transistor, comprising the following steps:

[0012] S1: Obtain characteristic points of the calibration gas in a two-dimensional coordinate system;

[0013] The horizontal coordinate of the characteristic point is the receptor function factor The vertical axis is the conversion function factor

[0014] in, is the change in surface potential of the gas-sensitive film in the gas-sensitive field-effect transistor, n is the number of gas molecules per unit volume, ΔI is the change in current of the gas-sensitive field-effect transistor, b1 is a constant related to temperature, and b2 is a constant related to the electrode channel of the gas-sensitive field-effect transistor;

[0015] S2: obtaining a characteristic space of the calibration gas in the two-dimensional coordinate system according to the characteristic points;

[0016] S3: Obtain the receptor function factor and conversion function factor of the gas to be identified, and determine whether the gas to be identified is the calibration gas based on whether the characteristic points corresponding to the receptor function factor and conversion function factor of the gas to be identified belong to the characteristic space.

[0017] Preferably,

[0018] Where k0 is the Boltzmann constant, T is the Kelvin temperature, S is the cross-sectional area of ​​the electrode channel in the gas-sensing field-effect transistor, and e is the basic charge.

[0019] Preferably, the feature space is a circumscribed ellipse of corresponding feature points.

[0020] Preferably, there are multiple characteristic points in step S1, and different characteristic points correspond to different gas concentrations of the calibration gas.

[0021] As further preferred, before step S1, the method further includes: obtaining the characteristic point according to a volt-ampere characteristic curve and a transfer characteristic curve of a calibration gas at a corresponding gas concentration in the gas-sensitive field effect transistor.

[0022] The present application also discloses a gas identification system applied to the above-mentioned gas identification method, wherein the gas identification system comprises a feature point acquisition module, a feature space module and a gas identification module;

[0023] The feature point acquisition module is used to obtain the feature points of the calibration gas on a two-dimensional coordinate system;

[0024] The feature space module obtains the feature space of the calibration gas on the two-dimensional coordinate system according to the different feature points;

[0025] The gas identification module is used to obtain the receptor function factor and the conversion function factor of the gas to be identified, and to determine whether the gas to be identified is the calibration gas.

[0026] In general, the above technical solutions conceived by this application have the following technical advantages compared with the prior art:

[0027] 1. This application is based on the principle that the gas-sensitive film of the gas-sensitive field effect transistor has the ability to convert gas stimulation into electrical signals through charge transfer at the gas-solid interface and electron transport in the solid; this application defines the receptor function factor x and the conversion function factor y as the characteristic points of the gas to describe the specificity of the interaction between the above-mentioned gas-sensitive film and the gas, and performs gas identification through the specificity of the gas-sensitive field effect transistor for specific gases in chemical reception and electron transduction, thereby reshaping the gas coding logic of the gas sensor;

[0028] 2. The encoding model of the receptor function factor x and the conversion function factor y corresponding to the characteristic points constructed in this application is simple and interpretable; this specific gas encoding method is expected to realize the identification of various gases by analyzing the electron transduction process generated by gas-solid interaction, and further combines the high integration advantages of gas-sensitive field-effect transistors and the rich selection of gas-sensitive thin film materials to expand the gas discrimination capability and pave the way for the development of the next generation of machine olfaction. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is a schematic diagram of the structure of the gas-sensitive field effect transistor gas sensor used in Example 1 of the present application;

[0030] Figure 2 The volt-ampere characteristic curve (I) of the gas-sensitive field effect transistor gas sensor provided in Example 1 of the present application in an atmosphere with different NO2 concentrations DS -V DS ), wherein the gas concentration range is 0 to 5 ppm, and the source-drain voltage range is -5 to 5 V;

[0031] Figure 3 The transfer characteristic curve of the gas field effect transistor gas sensor in Example 1 of the present application in an atmosphere with different NO2 concentrations (I DS -V G ), wherein the gas concentration range is 0 to 5 ppm, and the gate voltage range is -15 to 10 V;

[0032] Figure 4 The volt-ampere characteristic curve (I) of the gas-sensitive field effect transistor gas sensor provided in Example 1 of the present application in an atmosphere with different NO concentrations DS -V DS ), wherein the gas concentration range is 0 to 5 ppm, and the source-drain voltage range is -5 to 5 V;

[0033] Figure 5 The transfer characteristic curve of the gas field effect transistor gas sensor in Example 1 of the present application in an atmosphere with different NO concentrations (I DS -V G ), wherein the gas concentration range is 0 to 5 ppm, and the gate voltage range is -15 to 10 V;

[0034] Figure 6 It is the feature space corresponding to NO in the spatial map constructed by the two-dimensional matrix of Example 1 of the present application;

[0035] Figure 7 It is the feature space corresponding to NO2 in the spatial map constructed by the two-dimensional matrix of Example 1 of the present application;

[0036] In all drawings, the same reference numerals are used to denote the same elements or structures, wherein: 1 - substrate, 2 - gate insulating layer, 3 - source electrode, 4 - channel active layer, 5 - drain electrode, 6 - gate electrode. DETAILED DESCRIPTION

[0037] 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.

[0038] 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.

[0039] 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.

[0040] The present application discloses a specific gas coding method based on a gas-sensitive field effect transistor, and its application in gas identification. The gas-sensitive field effect transistor used in the specific gas coding method can be a thin film field effect transistor, a complementary metal oxide semiconductor device (CMOS device for short), or a high electron mobility transistor (HEMT for short). Among them, the gas-sensitive film in the field effect transistor can be a material such as quantum dots (such as colloidal quantum dots PbS), a two-dimensional material (such as two-dimensional MXene) or a metal oxide (such as cerium oxide, tungsten oxide or tin oxide); different gas-sensitive films correspond to different target gases. When the gas-sensitive film is cerium oxide, the target gas can be H2S or ethanol; when the gas-sensitive film is tungsten oxide, the target gas can be NH3 or acetone; when the gas-sensitive film is two-dimensional MXene, the target gas can be acetone or methanol; when the gas-sensitive film is tin oxide, the target gas can be H2 or CO.

[0041] Figure 1This is a schematic diagram of the structure of a typical gas-sensitive field effect transistor gas sensor. In this embodiment, it is a bottom-gate structure, with a semiconductor gas-sensitive film as both a channel active layer and a gas-sensitive layer. From bottom to top, it includes a substrate 1, a gate insulating layer 2, and a channel active layer 4. A source electrode 3 and a drain electrode 5 are also deposited on the channel active layer 4. The source electrode 3 and the drain electrode 5 are respectively located on opposite sides of the channel active layer 4. The channel active layer is made of semiconductor gas-sensitive material, and a gate electrode 6 is drawn out from one side of the substrate, thereby forming a gas-sensitive field effect transistor. The gas-sensitive field effect transistor used in this application is not limited to the above structure, and can adopt a channel sensitization method or a double-layer structure method.

[0042] The gas identification method comprises the following steps:

[0043] S11: Under a specific concentration, obtaining a volt-ampere characteristic curve and a transfer characteristic curve of the calibration gas in the gas-sensitive field effect transistor;

[0044] S12: According to the volt-ampere characteristic curve and the transfer characteristic curve, different characteristic points (x, y) of the calibration gas in the two-dimensional space composed of the receptor functional factor and the conversion functional factor are obtained;

[0045] Among them, receptor function factor Transfer Function Factor

[0046] τ is the number of gas molecules, is the surface potential change of the gas-sensitive film in the gas-sensitive field-effect transistor, n is the number of gas molecules per unit volume, k0 is the Boltzmann constant, T is the Kelvin temperature, and m gas is the mass of a single gas molecule, ΔI is the current change of the gas-sensing field-effect transistor, S is the cross-sectional area of ​​the channel through which the current flows in the gas-sensing field-effect transistor, and e is the basic charge;

[0047] Since the Kelvin temperature T and the cross-sectional area S of the channel through which the current flows in the gas-sensing field-effect transistor are constant when the temperature and the parameters of the gas-sensing field-effect transistor remain unchanged, and the distribution of the characteristic points will not change when the horizontal and vertical coordinates of the two-dimensional space are extended or compressed in equal proportion, the receptor function factor x and the conversion function factor y can also be simplified as Transfer Function Factor Among them, b1 is a constant related to temperature, and b2 is a constant related to the electrode channel of the gas-sensitive field-effect transistor.

[0048] S2: obtaining a characteristic space of the calibration gas in the two-dimensional space according to the different characteristic points;

[0049] S3: Acquire characteristic points of the gas to be identified, and determine whether the gas to be detected is the calibration gas based on whether the characteristic points of the gas to be identified belong to the characteristic space.

[0050] Specifically, the surface potential change of the gas-sensitive film in the gas-sensitive field-effect transistor The calculation can be done by following the steps below:

[0051] First, the hole mobility of the gas-sensing field-effect transistor is obtained Among them, It is the maximum value of the slope of the linear region corresponding to the transfer characteristic curve of the calibration gas or the gas to be identified in the linear coordinate system. i is the capacitance per unit area of ​​the gate insulating layer (usually SiO2), V DS is the source-drain voltage;

[0052] The conductivity σ of the gas-sensitive film is related to the carrier concentration p and the mobility μ p The relationship is as follows:

[0053] σ=peμ P

[0054] Furthermore, according to the formula Get the Fermi level change ΔE F , p0 is the carrier concentration of the gas-sensitive film when the target gas is not introduced; k0 is the Boltzmann constant, which is 1.38×10 -23 (J.K -1 ). T is Kelvin temperature (K).

[0055] Fermi level change (ΔE F ) depends on the change in carrier concentration of the gas-sensitive film as the gas concentration changes. Therefore, the change in surface potential of the gas-sensitive film can be further calculated. according to Can be established The equation between and conductivity is finally solved to Among them, a0 and They respectively represent the maximum value of the slope of the linear region corresponding to the transfer characteristic curve in the linear coordinate system and the conductivity of the gas sensitive film when it acts with a blank control gas (such as air, nitrogen, etc.).

[0056] The physical meaning of the receptor function factor x is the change in surface potential of the gas-sensitive material per unit area caused by a single target gas molecule (τ) per unit time. It can be used to measure the charge transfer capacity of the gas-solid interface; therefore Among them, τ can be calculated based on the Maxwell velocity distribution function, the formula is Therefore, as long as the number of molecules of the target gas with a concentration of c ppm per unit volume is calculated, and knowing the mass m of a single gas molecule gas We can measure τ and then calculate Avogadro's constant N A =6.02×10 -23 .

[0057] The conversion function factor y is the change in the surface density of the electron flow in the conductive channel caused by the surface potential difference, which is used to measure the electron transduction ability of the gas sensor. The product of the two factors is the MCE molecular conversion efficiency, which is the ratio of the number of charge carriers collected by the gas sensor to the number of gas molecules it adsorbs, and is a constant under the condition that the gas concentration and type remain unchanged. ΔJ is the current density, which can be obtained by It is deduced that ΔI is the current change of the gas-sensitive field effect transistor, which can be obtained through the volt-ampere characteristic curve, and S is the cross-sectional area of ​​the channel material through which the current passes.

[0058] In some embodiments, when there are two or more calibration gases in step S1, the corresponding feature spaces constructed in step S2 are also two or more, and they do not overlap with each other; in step S3, based on which feature space the characteristic points of the gas to be identified belong to / or whether they do not belong to any feature space, it is determined which calibration gas the gas to be detected belongs to.

[0059] In other embodiments, the corresponding feature space may be found by constructing a circumscribed ellipse of feature points.

[0060] The present application also discloses a gas identification system applied to the above-mentioned gas identification method, including a feature point acquisition module, a feature space module and a gas identification module;

[0061] The feature point acquisition module is used to obtain the feature points of the calibration gas on a two-dimensional coordinate system;

[0062] The feature space module obtains the feature space of the calibration gas on the two-dimensional coordinate system according to the different feature points;

[0063] The gas identification module is used to obtain the receptor function factor and the conversion function factor of the gas to be identified, and to determine whether the gas to be identified is the calibration gas.

[0064] The transistor-based gas information (concentration and type) encoding expression is a two-dimensional matrix w = {(x, y)} of the above two factors. In order to visualize the decoding process, the obtained encoding matrix is ​​generated into a three-dimensional gas space, and each gas can be identified by the projection of the encoding on this space map. With the diversification of semiconductor materials and the integration of transistor-type gas sensors, it is expected to build a huge gas encoding database. If the gas and encoding of a single gas-sensitive field-effect transistor gas sensor are difficult to correspond, integrate more gas-sensitive field-effect transistor gas sensors to improve differentiation and judgment.

[0065] Example 1 Coding of NO2 Gas and NO Gas Based on PbS Colloidal Quantum Dot Thin Film Field Effect Transistor Gas Sensor

[0066] S11: The PbS colloidal quantum dot thin film field effect transistor used in this embodiment is as follows Figure 1 As shown, it is a bottom-gate structure, which includes a substrate 1, a gate insulating layer 2, and a channel active layer 4 from bottom to top. A source electrode 3 and a drain electrode 5 are also deposited on the channel active layer. The source electrode 3 and the drain electrode 5 are respectively located on two opposite sides of the channel active layer 4, and a gate electrode 6 is led out from one side of the substrate. The semiconductor gas-sensitive film formed by the deposition of PbS colloidal quantum dots by a solution method serves as a channel active layer and a gas-sensitive layer at the same time.

[0067] S12: Using nitrogen, dilute NO2 and NO gas to different concentration gradients such as 0ppm, 0.2ppm, 0.5ppm, 1ppm, 2ppm, 5ppm, and measure the corresponding volt-ampere characteristic curve and transfer characteristic curve; wherein, Figure 2 and Figure 3 They are respectively the voltammetric characteristic curve and transfer characteristic curve of NO2; Figure 4 and Figure 5 They are the voltammetric characteristic curve and transfer characteristic curve of NO respectively.

[0068] S13: Using semiconductor physics theory formulas, the conductivity ρ and hole mobility μ are extracted from the volt-ampere characteristic curve and transfer characteristic curve. p , carrier (hole) concentration p0, Fermi level change ΔE F , surface potential change (i.e., the change in surface potential of the gas-sensitive film in the gas-sensitive field-effect transistor) and other electrical parameters, as well as the cross-sectional area S of the current passing through the gas-sensitive film, as shown in Table 1.

[0069] Table 1 Calculation of electrical parameters of the sensor in Example 1 at different NO2 concentrations

[0070]

[0071] The relevant semiconductor physics theory formulas and device parameters are as follows:

[0072]

[0073] R is the resistance of the PbS gas-sensitive film, ρ is the resistivity of the gas-sensitive film, L is the electrode spacing (also known as the channel length of the field-effect transistor, 10 μm), and W is the channel width (4.8 mm). The cross-sectional area of ​​the current passing through the gas-sensitive film is:

[0074] S=Wd PbS

[0075] d PbS is the thickness of the gas-sensitive film, the test result is 17nm, d SiO2 is the thickness of the gate insulation layer. The conductivity (σ) is inversely proportional to the resistivity ρ:

[0076]

[0077] In order to calculate the surface potential change associated with the receptor functional factor By formula It can be seen that the potential change With ΔE F related to; further by ΔE F Related to the carrier concentration p; through σ = peμ p It can be seen that p is related to conductivity σ and mobility μ p So we need to find σ and μ first. p .

[0078] The calculation formula of thin film transistor (TFT) mobility is as follows:

[0079]

[0080] μ p is the hole mobility, is the slope of the linear region corresponding to the transfer characteristic curve in the linear coordinate system (the slope is the maximum value of the curve at this time), C i is the capacitance per unit area of ​​the gate insulating layer (SiO2), V DS is the source-drain voltage. The relationship between conductivity, carrier concentration and mobility is as follows:

[0081] σ=peμ p

[0082] p is the carrier (hole) concentration.

[0083] S14: Further, using the formula receptor function factor Transfer Function Factor The receptor function factor and conversion function factor values ​​corresponding to NO2 and NO atmospheres were calculated respectively, as shown in Table 2.

[0084] in, is the change in the surface potential of the gas-sensitive film, n is the number of gas molecules per unit volume, k0 is the Boltzmann constant, T is the Kelvin temperature, and m gas is the mass of a single gas molecule, ΔI is the output current of the gas-sensing field-effect transistor, S is the cross-sectional area of ​​the channel through which the current flows in the gas-sensing field-effect transistor, and e is the basic charge.

[0085] Table 2 Acceptor function factor and conversion function factor values ​​corresponding to NO2 and NO atmosphere

[0086]

[0087]

[0088] S2: Encode the different receptor function factors and conversion function factor values ​​corresponding to the same gas in Table 2 into a two-dimensional matrix, and graphically mark them on the two-dimensional space composed of receptor function factors and conversion function factors, such as Figure 6-7 As shown; further, we distinguish the positions occupied by different gases in the two-dimensional space by finding the circumscribed ellipse corresponding to the points of the two-dimensional matrix; for PbS colloidal quantum dots, the (x, y) in NO2 atmosphere at the same concentration is higher than that in NO atmosphere, which may be due to the higher reactivity of NO2 molecules. For example, under 1ppm NOx, the x value of PbS CQDs TFT in NO2 atmosphere is almost 1.66 times that of NO, and the y value is almost 1.83 times that of NO.

[0089] S3: The type of the gas to be tested is determined by judging whether the characteristic point (i.e., the receptor function factor and the conversion function factor value) of the gas to be tested is located within the circumscribed ellipse corresponding to NO2 or NO, thereby realizing the identification of the gas to be tested; Taking this embodiment as an example, when the characteristic point (x, y) of the gas to be tested is determined by the same method in steps S11-S14, it is located within Figure 6 If the gas to be tested is within the blue ellipse, it is judged that the gas to be tested is NO; when the characteristic point (x, y) of the gas to be tested is located at Figure 7 If it is within the red oval, the gas to be tested is judged to be NO2.

[0090] Example 2

[0091] Example 1 is repeated with the same steps, except that the upper layer of the semiconductor gas-sensitive film is PbS colloidal quantum dots and the lower layer is MoS2, and the thickness of each layer is the same as the thickness of the PbS colloidal quantum dots in Example 1.

[0092] Example 3

[0093] Example 1 is repeated with the same steps, except that the PbS colloidal quantum dot thin film field effect transistor gas sensor of Example 1 is replaced by a complementary metal oxide semiconductor field effect transistor. The preparation method of the complementary metal oxide semiconductor field effect transistor is prepared with reference to "MOSFET Based Different Structures for Sensor Applications: A Review" (2024 First International Conference on Electronics, Communication and Signal Processing, 08-10 August 2024). The structure of the complementary metal oxide semiconductor field effect transistor is semiconductor silicon, dielectric SiO2, source, drain, and gate metal electrodes from bottom to top, and a SnO2 gas-sensitive film is deposited by a drop coating process at the gas-sensitive unit, thereby forming a complementary metal oxide semiconductor field effect transistor gas sensor.

[0094] Example 4

[0095] Example 1 is repeated with the same steps, except that the PbS colloidal quantum dot thin film field effect transistor gas sensor of Example 1 is replaced with a high electron mobility transistor gas sensor. The high electron mobility transistor gas sensor is prepared according to the same method in the document "Quantum Dots-Sensitized High Electron Mobility Transistor (HEMT) for Sensitive NO2 Detection" (Chemosensors, 2023, 11 (4): 252). Its structure mainly includes a GaAs epitaxial layer, a control gate, a gas-sensitive film, an extended gate, a source and a drain. The control gate and the extended gate are located in a horizontal direction, and a PbS quantum dot gas-sensitive film is deposited between the control gate and the extended gate, thereby forming a PbS quantum dot high electron mobility transistor gas sensor.

[0096] When steps S1 to S3 of Example 1 are repeated for Example 2 to Example 4, effects similar to those of Example 1 can be obtained.

[0097] This application takes PbS colloidal quantum dot film as an example, and constructs a field effect transistor gas sensor as the gas-sensitive layer, which can ultimately achieve intelligent identification of NO2 and NO gases. By specifically designing gas-sensitive materials that are sensitive to other gases as the sensor gas-sensitive layer, after replacing the gas-sensitive film material using the method provided in this application, intelligent identification of other target gases such as NO, H2S, NH3, etc. can also be achieved. At the gas-sensitive material level, the gas-sensitive material's gas-sensitive properties can be changed by regulating the temperature, chemical synthesis ratio, doping, compounding, and construction of heterojunctions during the synthesis of the gas-sensitive material, thereby regulating the surface potential between the gas and the gas-sensitive material. To affect the parameters of the receptor functional factor. In the gas-sensitive field-effect transistor device structure method, by adjusting the size of the channel electrode and changing the dielectric material of the transistor, the cross-sectional area of ​​the device channel and the output current parameters are optimized, thereby affecting the parameters of the conversion functional factor. In addition, combining the application of different source-drain voltages and gate voltages can provide more data and design freedom for encoding, which is expected to further improve the ability of gas sensors to identify gas types, accuracy and concentration ranges, thereby bringing more efficient and accurate technical support to the field of gas monitoring.

[0098] 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 specific gas encoding method based on gas-sensitive field effect transistor, characterized in that: include: Obtaining a receptor functional factor x and a conversion functional factor y as characteristic points of the gas to achieve specific gas coding; Among them, receptor function factor Transfer Function Factor is the surface potential change of the gas-sensitive film in the gas-sensitive field-effect transistor, n is the number of gas molecules per unit volume, m gas is the mass of the gas molecules, ΔI is the current change of the gas-sensing field-effect transistor, b1 is a constant related to temperature, and b2 is a constant related to the electrode channel of the gas-sensing field-effect transistor.

2. The specific gas coding method according to claim 1, characterized in that: Where k0 is the Boltzmann constant, T is the Kelvin temperature, S is the cross-sectional area of ​​the electrode channel in the gas-sensing field-effect transistor, and e is the basic charge.

3. The specific gas coding method according to claim 1, characterized in that: Characteristic points of the gas at different concentrations are obtained, and a characteristic space of the gas is obtained according to the characteristic points.

4. The specific gas coding method according to claim 1, characterized in that: The material of the gas-sensitive film of the gas-sensitive field effect transistor is quantum dots, two-dimensional materials or metal oxides.

5. A gas identification method based on a gas-sensitive field effect transistor, characterized in that: The following steps are involved: S1: Obtain characteristic points of the calibration gas in a two-dimensional coordinate system; The horizontal coordinate of the characteristic point is the receptor function factor The vertical axis is the conversion function factor in, is the surface potential change of the gas-sensitive film in the gas-sensitive field-effect transistor, n is the number of gas molecules per unit volume, m gas is the mass of gas molecules, ΔI is the current change of the gas-sensing field effect transistor, b1 is a constant related to temperature, and b2 is a constant related to the electrode channel of the gas-sensing field effect transistor. ; S2: obtaining a characteristic space of the calibration gas in the two-dimensional coordinate system according to the characteristic points; S3: Obtain the receptor function factor and conversion function factor of the gas to be identified, and determine whether the gas to be identified is the calibration gas based on whether the characteristic points corresponding to the receptor function factor and conversion function factor of the gas to be identified belong to the characteristic space.

6. The gas identification method according to claim 5, characterized in that: Where k0 is the Boltzmann constant, T is the Kelvin temperature, S is the cross-sectional area of ​​the electrode channel in the gas-sensing field-effect transistor, and e is the basic charge.

7. The gas identification method according to claim 5, characterized in that: The feature space is the circumscribed ellipse of the corresponding feature points.

8. The gas identification method according to claim 5, characterized in that: There are multiple characteristic points in step S1, and different characteristic points correspond to different gas concentrations of the calibration gas.

9. The gas identification method according to claim 8, characterized in that: Before step S1, the method further includes: obtaining the characteristic point according to the volt-ampere characteristic curve and the transfer characteristic curve of the calibration gas at the corresponding gas concentration in the gas-sensitive field effect transistor.

10. A gas identification system, applied to the gas identification method according to any one of claims 5 to 9, characterized in that: It includes feature point acquisition module, feature space module and gas identification module; The feature point acquisition module is used to obtain the feature points of the calibration gas on a two-dimensional coordinate system; The feature space module obtains the feature space of the calibration gas on the two-dimensional coordinate system according to the different feature points; The gas identification module is used to obtain the receptor function factor and the conversion function factor of the gas to be identified, and to determine whether the gas to be identified is the calibration gas.

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