A specific gas coding method based on gas-sensitive field effect transistor and application thereof

Abstract

The application belongs to the field of gas sensors, and specifically discloses a specific gas coding method based on a gas-sensitive field effect transistor and application. The specific gas coding method comprises: obtaining a receptor function factor and a conversion function factor as characteristic points of a gas, so as to realize specific gas coding; wherein, is a surface potential change amount of a gas-sensitive thin film in the gas-sensitive field effect transistor, n is a gas molecule number per unit volume, m gas is a mass of a gas molecule, is a current change amount 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. The application utilizes the advantage that electrical parameters of a field effect transistor gas sensor can be extracted to analyze an electronic transduction process generated by gas-solid interaction, and thus different gases can be distinguished.

Description

Technical Field

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

[0002] Semiconductor gas sensors, as a crucial component of artificial intelligence sensing technology, have significantly expanded our ability to acquire gas information from the objective world, enabling us to effectively address the potential threats of colorless, odorless, toxic, harmful, flammable, and explosive gases. They also demonstrate immense application potential in medical fields such as respiratory diagnosis and olfactory disorder treatment. However, traditional semiconductor gas sensors suffer from limitations in gas identification, exhibiting broad-spectrum response but insufficient specificity. To address this issue, bio-inspired machine olfactory systems, such as electronic noses, have emerged. These systems employ a series of semiconductor gas sensors to mimic the olfactory receptor cells of mammals, combined with advanced pattern recognition algorithms, to achieve the identification of various gases.

[0003] Compared with the widely used machine vision technology, the development of electronic nose technology is relatively lagging. Although commercial electronic noses have been applied in the food industry and agriculture, their gas encoding capabilities are still affected by the cross-sensitivity of gas sensors, resulting in insufficient sensor specificity. This 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 encoding method to achieve intelligent identification of specific target gases. Existing semiconductor gas-sensitive devices have the characteristics of high gas detection sensitivity, fast response time, low manufacturing cost, and easy miniaturization, and are suitable for fabricating micro sensors. Therefore, they have become the focus of sensor research in recent years (Research progress of nanostructure thin film gas-sensitive sensors, Physics, 2014, 43(06):364-372.). However, usually one gas-sensitive material corresponds to multiple types of gases, and there are problems such as cross-sensitivity and insufficient specificity when detecting gases. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the purpose of this application is to provide a specific odor encoding method and a gas identification method based on a gas-sensitive field-effect transistor. By utilizing the extractable electrical parameters of the field-effect transistor gas sensor, the electronic transduction process generated by gas-solid interaction is analyzed, thereby encoding specific gases and achieving the differentiation of different gases.

[0005] To achieve the above objectives, this application provides a specific gas encoding method based on a gas-sensitive field-effect transistor, comprising: obtaining the acceptor functional factor x and the switching functional factor y as feature points of the gas to achieve specific gas encoding;

[0006] Among them, receptor functional factors Conversion function factor The change in surface potential of the gas-sensitive thin film in a gas-sensitive field-effect transistor is denoted by n, where n is the number of gas molecules per unit volume, and m is the number of gas molecules per unit volume. gas Let b1 be the mass of the gas molecules, ΔI be the change in current of the gas-sensitive field-effect transistor, b1 be a constant related to temperature, and b2 be a constant related to the electrode channel of the gas-sensitive field-effect transistor.

[0007] Preferred,

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

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

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

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

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

[0013] The x-axis of the feature point represents the receptor functional factor. The vertical axis represents the transformation function factor.

[0014] in, ΔI is the change in surface potential of the gas-sensitive thin 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: Based on the feature points, obtain the feature space of the calibration gas in the two-dimensional coordinate system;

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

[0017] Preferred,

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

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

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

[0021] As a further preferred embodiment, before step S1, the method further includes: obtaining the feature point based on the current-voltage characteristic curve and transfer characteristic curve of the calibration gas in the gas-sensitive field-effect transistor at the corresponding gas concentration.

[0022] This application also discloses a gas identification system applied to the above-mentioned gas identification method, the gas identification system including 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 in a two-dimensional coordinate system;

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

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

[0026] In summary, compared with the prior art, the technical solutions conceived in this application have the following main technical advantages:

[0027] 1. This application is based on a gas-sensitive thin film of a gas-sensitive field-effect transistor, which has the ability to convert gas stimuli into electrical signals through charge transfer at the gas-solid interface and electron transport in the solid. This application defines the receptor functional factor x and the conversion functional factor y as characteristic points of the gas to describe the specificity of the interaction between the gas-sensitive thin film and the gas. Gas identification is performed by the specificity of the gas-sensitive field-effect transistor for a specific gas in terms of chemical reception and electron transduction, thus reshaping the gas encoding logic of the gas sensor.

[0028] 2. The encoding models of receptor functional factor x and switching functional factor y corresponding to the feature points constructed in this application are simple and interpretable; this specific gas encoding method is expected to achieve the recognition of various gases by analyzing the electron transduction process generated by gas-solid interaction. Furthermore, by combining the high integration advantage of gas-sensitive field-effect transistors and the rich selection of gas-sensitive thin film materials, the gas discrimination capability is expanded, paving the way for the development of next-generation machine olfaction. Attached Figure Description

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

[0030] Figure 2 The current-voltage characteristic curves (I) of the gas-sensitive field-effect transistor gas sensor provided in Embodiment 1 of this application are shown in different NO2 atmosphere environments. DS -V DS The gas concentration range is 0–5 ppm, and the source-drain voltage range is -5–5 V.

[0031] Figure 3 This is the transfer characteristic curve of the gas-sensitive field-effect transistor gas sensor in Embodiment 1 of this application under different NO2 concentration atmospheres (I) DS -V G The gas concentration range is 0–5 ppm, and the gate voltage range is -15–10 V.

[0032] Figure 4 This is the current-voltage characteristic curve (I) of the gas-sensitive field-effect transistor gas sensor provided in Embodiment 1 of this application under different NO atmosphere environments. DS -V DS ); where is the gas concentration range of 0 to 5 ppm and the source-drain voltage range of -5 to 5 V;

[0033] Figure 5 This is the transfer characteristic curve of the gas-sensitive field-effect transistor gas sensor in Embodiment 1 of this application under different NO concentration atmospheres (I) DS -V G The gas concentration range is 0–5 ppm, and the gate voltage range is -15–10 V.

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

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

[0036] In all the figures, 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 Implementation

[0037] 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.

[0038] 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.

[0039] 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.

[0040] This application discloses a specific gas encoding method based on a gas-sensitive field-effect transistor (FET), and its application in gas identification. The FET used in this specific gas encoding method can be a thin-film field-effect transistor (TFT), a complementary metal-oxide-semiconductor (CMOS) device, or a high electron mobility transistor (HEMT). The gas-sensitive thin film in the TFT can be a quantum dot (e.g., colloidal quantum dot PbS), a two-dimensional material (e.g., two-dimensional MXene), or a metal oxide (e.g., 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; and when the gas-sensitive film is tin oxide, the target gas can be H2 or CO.

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

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

[0043] S11: Obtain the current-voltage characteristic curve and transfer characteristic curve of the calibration gas in the gas-sensitive field-effect transistor at a specific concentration;

[0044] S12: Based on the current-voltage characteristic curve and the transfer characteristic curve, obtain the different characteristic points (x,y) of the calibration gas in the two-dimensional space composed of the acceptor functional factor and the transfer functional factor;

[0045] Among them, receptor functional factors Conversion function factor

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

[0047] Since the Kelvin temperature T and the cross-sectional area S of the channel through which the current flows in the gas-sensitive field-effect transistor are constant when the parameters of the temperature and gas-sensitive field-effect transistor remain unchanged; and since the distribution of feature points does not change under the condition that the horizontal and vertical coordinates are extended or compressed proportionally in two-dimensional space, the acceptor function factor x and the switching function factor y can still be simplified to: Conversion function factor Where b1 is a temperature-dependent constant, and b2 is a constant related to the electrode channel of the gas-sensitive field-effect transistor.

[0048] S2: Based on the different feature points, obtain the feature space of the calibration gas in the two-dimensional space;

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

[0050] Specifically, the change in surface potential of the gas-sensitive thin film in a gas-sensitive field-effect transistor. The calculation can be performed using the following steps:

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

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

[0053] σ=peμ P

[0054] Furthermore, according to the formula Obtain 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, taken as 1.38 × 10⁻⁶. -23 (J.K.) -1 T represents the Kelvin temperature (K).

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

[0056] The physical meaning of the receptor functional 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 capability of the gas-solid interface; therefore Wherein, τ can be calculated based on Maxwell's velocity distribution function, as shown in the formula: 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 τ can then be measured, and thus, the following can be calculated: Avogadro's constant N A =6.02×10 -23 .

[0057] The conversion function factor γ represents the change in electron surface density in the conductive channel caused by the surface potential difference, and is used to measure the electron transduction capability of a 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; it 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 from the current-voltage 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, there are also two or more corresponding feature spaces constructed in step S2, and they do not overlap with each other; in step S3, the gas to be detected is determined to be a calibration gas based on which feature space the feature points of the gas to be identified belong to / or do not belong to any feature space.

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

[0060] This 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 in a two-dimensional coordinate system;

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

[0063] The gas identification module is used to acquire the acceptor function factor and 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 two factors mentioned above. To visualize the decoding process, the acquired encoding matrix is ​​used to generate a three-dimensional gas space, where each gas can be identified by projecting its encoding onto this spatial map. With the diversification of semiconductor materials and the integration of transistor-type gas sensors, it is expected that a vast gas encoding database can be built. If the gas and encoding of a single gas-sensitive field-effect transistor gas sensor are difficult to match, integrating a larger number of gas-sensitive field-effect transistor gas sensors can improve differentiation and judgment.

[0065] Example 1: Encoding of NO2 and NO gases using a 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, from bottom to top, a substrate 1, a gate insulating layer 2, and a channel active layer 4. An active electrode 3 and a drain electrode 5 are also deposited on the channel active layer. The source electrode 3 and drain electrode 5 are located on 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 thin film formed by PbS colloidal quantum dots through solution deposition serves simultaneously as the channel active layer and the gas-sensitive layer.

[0067] S12: NO2 and NO gas were diluted with nitrogen to different concentration gradients of 0 ppm, 0.2 ppm, 0.5 ppm, 1 ppm, 2 ppm, and 5 ppm, respectively, and the corresponding voltammetric and transfer characteristic curves were measured; among them, Figure 2 and Figure 3 The current-voltage characteristic curve and transfer characteristic curve of NO2 are shown below; Figure 4 and Figure 5 The figures show the current-voltage characteristic curve and the transfer characteristic curve of NO, respectively.

[0068] S13: Using semiconductor physics formulas, the conductivity ρ and hole mobility μ are extracted from the current-voltage characteristic curve and the transfer characteristic curve. p Carrier (hole) concentration p0, Fermi level change ΔE F Surface potential change The electrical parameters, such as the change in surface potential of the gas-sensitive thin film in the gas-sensitive field-effect transistor, and the cross-sectional area S of the gas-sensitive thin film through which the current passes are measured, are 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 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 through which current flows through the gas-sensitive film is:

[0074] S=Wd PbS

[0075] d PbS The thickness of the gas-sensitive thin film is 17 nm, as measured by the test. SiO2 This refers to the thickness of the gate insulating layer. Conductivity (σ) is inversely proportional to resistivity ρ.

[0076]

[0077] To calculate the surface potential change related to receptor functional factors From the formula It can be seen that the change in electric potential With ΔE F Related to; further by ΔE F Related to carrier concentration p; via σ = peμ p It can be seen that p is related to conductivity σ and mobility μ p Therefore, it is necessary to first determine σ and μ. p .

[0078] The formula for calculating the mobility of a thin-film transistor (TFT) is as follows:

[0079]

[0080] μ p It is hole mobility. It is the slope of the linear region corresponding to the transfer characteristic curve in the linear coordinate system (where the slope is the maximum value of the curve), C i It is the capacitance per unit area of ​​the gate insulating layer (SiO2), V DS The source-drain voltage is given. The relationship between conductivity and 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 functional factor Conversion 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, Let n be the change in surface potential of the gas-sensitive thin film, n be the number of gas molecules per unit volume, k0 be the Boltzmann constant, T be the Kelvin temperature, and m be the constant. gas Let denot be the mass of a single gas molecule, ΔI be the output current of the gas-sensitive field-effect transistor, S be the cross-sectional area of ​​the channel through which the current flows in the gas-sensitive field-effect transistor, and e be the elementary charge.

[0085] Table 2. Receptor functional factors and conversion functional factors corresponding to NO2 and NO atmosphere.

[0086]

[0087]

[0088] S2: Encode the different receptor functional factors and switching functional factors corresponding to the same gas in Table 2 into a two-dimensional matrix, and graphically represent them on the two-dimensional space composed of receptor functional factors and switching functional factors, such as... Figure 6-7 As shown; further, we distinguish the positions occupied by different gases in two-dimensional space by finding the circumscribed ellipse of the points corresponding to the two-dimensional matrix; for PbS colloidal quantum dots, the (x,y) values ​​are higher in NO2 atmosphere at the same concentration than in NO atmosphere, which may be due to the higher reactivity of NO2 molecules. For example, at 1 ppm 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 gas to be tested is determined by judging whether the characteristic points (i.e., acceptor function factor and conversion function factor values) of the gas to be tested are 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 points (x, y) of the gas to be tested are located within the circumscribed ellipse corresponding to NO2 or NO, the gas to be tested is identified. Figure 6 If the target gas is within the blue ellipse, then the gas to be tested is determined to be NO; if the target gas is within the characteristic point (x,y) determined by the same method in steps S11-S14, then the target gas is within the blue ellipse. Figure 7 If the gas is found to be within the red ellipse, then the gas to be tested is determined to be NO2.

[0090] Example 2

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

[0092] Example 3

[0093] The same steps as in Example 1 were repeated, except that a complementary metal-oxide-semiconductor (CMOS) field-effect transistor (MOSFET) was used instead of the PbS colloidal quantum dot thin-film MOSFET gas sensor of Example 1. The CMOS MOSFET was fabricated according to the method described in "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 this CMOS MOSFET, from bottom to top, consists of semiconductor silicon, dielectric SiO2, and source, drain, and gate metal electrodes. A SnO2 gas-sensitive thin film was deposited at the gas-sensitive unit using a drop-coating process, thus constituting the CMOS MOSFET gas sensor.

[0094] Example 4

[0095] The same steps as in Example 1 were repeated, except that a high electron mobility transistor (HEMT) gas sensor was used instead of the PbS colloidal quantum dot thin-film field-effect transistor (FET) gas sensor in Example 1. The HEMT gas sensor was fabricated using the same method described in the literature "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 thin film, an extended gate, a source, and a drain. The control gate and the extended gate are located horizontally, and a PbS quantum dot gas-sensitive thin film is deposited between the control gate and the extended gate, thus forming the PbS quantum dot HEMT gas sensor.

[0096] When repeating steps S1-S3 of Example 1 for Examples 2-4, similar effects as in Example 1 can be obtained.

[0097] This application uses PbS colloidal quantum dot thin film as an example to construct a field-effect transistor gas sensor as a gas-sensitive layer, ultimately enabling intelligent identification of NO2 and NO gases. By specifically designing gas-sensitive materials sensitive to other gases and using them as the gas-sensitive layer of the sensor, the intelligent identification of other target gases such as NO, H2S, and NH3 can also be achieved by replacing the gas-sensitive thin film material using the method provided in this application. At the gas-sensitive material level, the gas-sensitive characteristics of the gas-sensitive material can be changed by controlling the temperature, chemical synthesis ratio, doping, composite, and construction of heterojunctions during the gas-sensitive material synthesis process, thereby controlling the surface potential between the gas and the gas-sensitive material. This influences the receptor functional factor parameters. In the structural methods of gas-sensitive field-effect transistor devices, by adjusting the size of the channel electrodes 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 conversion functional factor parameters. Furthermore, by applying different source-drain voltages and gate voltages, more data and design freedom can be provided for encoding, potentially further improving the ability of gas sensors to identify gas types, accuracy, and concentration range, thus bringing more efficient and accurate technical support to the field of gas monitoring.

[0098] 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 specific gas coding method based on a gas-sensitive field effect transistor, characterized by, The method comprises the following steps: Receptor function factor x and conversion function factor y As a characteristic point of the gas to realize a specific gas code; wherein the receptor function factor , the conversion function factor ; is the surface potential change amount of the gas sensitive thin 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 molecule, is the current change amount of the gas sensitive field effect transistor, b 1 is a constant related to temperature, b 2 is a constant related to the electrode channel of the gas sensitive field effect transistor.

2. The specific gas coding method according to claim 1, wherein ， ； wherein k 0 is the Boltzmann constant, T is the Kelvin temperature, S is the cross-sectional area of the electrode channel in the gas-sensitive field effect transistor, and e is the elementary charge.

3. The specific gas coding method of claim 1, wherein, Obtaining characteristic points of the gas at different concentrations, and obtaining a characteristic space of the gas according to the characteristic points.

4. The specific gas coding method of claim 1, wherein, The material of the gas-sensitive thin 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 by, The method comprises the following steps: S1: obtaining characteristic points of a calibration gas in a two-dimensional coordinate system; The abscissa of the feature point is a receptor function factor The ordinate is a conversion function factor ; wherein, is the amount of change in surface potential of the gas sensitive thin 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 molecule, is the amount of change in current of the gas sensitive field effect transistor, b 1 is a constant related to temperature, b 2 is a constant related to the electrode channel of the gas sensitive field effect transistor; S2: obtaining a characteristic space of the calibration gas in the two-dimensional coordinate system according to the characteristic points; S3: obtaining a receptor function factor and a conversion function factor of a to-be-identified gas, and determining whether the to-be-identified gas is the calibration gas according to whether the characteristic points corresponding to the receptor function factor and the conversion function factor of the to-be-identified gas belong to the characteristic space.

6. The gas identification method according to claim 5, wherein ， ； wherein k 0 is the Boltzmann constant, T is the Kelvin temperature, S is the cross-sectional area of the electrode channel in the gas-sensitive field effect transistor, and e is the elementary charge.

7. The gas identification method according to claim 5, wherein The characteristic space is an ellipse circumscribed around the corresponding characteristic points.

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

9. The gas identification method according to claim 8, wherein Before the step S1, the method further comprises the following step: obtaining the characteristic points according to a volt-ampere characteristic curve and a transfer characteristic curve of the calibration gas in the gas-sensitive field effect transistor at corresponding gas concentrations.

10. A gas identification system applied to the gas identification method of any one of claims 5 to 9, characterized by, The method comprises a characteristic point acquisition module, a characteristic space module and a gas identification module; The characteristic point acquisition module is used for obtaining characteristic points of a calibration gas in a two-dimensional coordinate system; The characteristic space module obtains a characteristic space of the calibration gas in the two-dimensional coordinate system according to different characteristic points; The gas identification module is used for obtaining a receptor function factor and a conversion function factor of a to-be-identified gas, and determining whether the to-be-identified gas is the calibration gas.

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