A gate-sensitive field effect transistor olfactory sensor and a method for preparing the same
By simulating the structure of biological olfactory neurons in field effect transistors, using Schottky contact between high electron mobility transistors and gas-sensitive films, the problems of low sensor sensitivity and complex sampling circuits in the prior art are solved, and high sensitivity and large-scale Integrated gas sensor.
Patent Information
- Application Number
- CN202211064854.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2022-09-01
- Publication Date
- 2024-12-27
- Estimated Expiration
- 2042-09-01
AI Technical Summary
Existing field effect transistor gas sensors rely on gate capacitance effect to operate, resulting in low sensitivity and complex sampling circuits, making it difficult to achieve large-scale on-chip integration.
Design a gate-sensitive field effect transistor olfactory sensor, whose structure simulates biological olfactory neurons, uses high electron mobility transistors and gas-sensitive films to form Schottky contact with the extended gate. The gas-sensitive film acts as an odor receptor and is driven by Voltage-controlled sensing signals, combining signal feature engineering and deep learning algorithms to improve sensor specificity.
Improve the signal transduction capability and sensitivity of the sensor, simplify the sampling circuit, realize large-scale array integration, and spatially separate the conductivity of semiconductor gas-sensitive receptor materials from high electron mobility transistors, improving design freedom and signal noise Compare.
Smart Images
Figure CN115561294B_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the field of intelligent sensors, and more specifically, relates to a gate-sensitive field effect transistor olfactory sensor and a preparation method thereof. Background Art
[0002] Olfactory sensors simulate the olfactory system of organisms and accurately identify gases or odors based on the influence of gas molecules on the sensor's electrical signals. They are widely used in public safety, food industry, environmental monitoring, and medical testing.
[0003] Existing olfactory sensors mainly use a two-terminal resistor device structure, which works by transducing the interaction between gas molecules and semiconductor gas-sensitive materials into changes in the resistance of gas-sensitive thin films. Since semiconductor gas-sensitive materials need to be responsible for both gas molecule recognition and electrical signal transduction, the two are mutually restricted during design, resulting in high operating temperatures and high power consumption, making it difficult to achieve large-scale integration. By constructing a gate-sensitive field-effect transistor gas sensor, the molecular recognition function and electrical signal transduction function of semiconductor gas-sensitive materials can be separated in space, thereby improving the signal transduction capability of the gas sensor. The prior art discloses a gas sensor with a gate-sensitive field-effect transistor device structure based on the capacitance effect of gas-sensitive thin films (Nanoscale, 2018, 10, 18019), which relies on the capacitance effect of the gate gas-sensitive material to work, has low sensitivity and needs to be driven by a pulsed gate voltage, so the sampling circuit is complex and difficult to achieve large-scale on-chip integration. Summary of the invention
[0004] In view of the defects of the prior art, the purpose of the present invention is to provide a gate-sensitive field-effect transistor olfactory sensor and a preparation method thereof, aiming to solve the problem that the existing field-effect transistor gas sensor relies on the gate capacitance effect to work, resulting in low sensor sensitivity and complex sampling circuit, making it difficult to achieve large-scale on-chip integration.
[0005] To achieve the above-mentioned purpose, the present invention provides a gate-sensitive field effect transistor olfactory sensor, which simulates biological olfactory neurons in structure, including a high electron mobility transistor and a gas-sensitive film, wherein the gate of the high electron mobility transistor includes a control gate and an extended gate, and the gas-sensitive film between the two serves as an odor receptor; the control gate and the extended gate are located in a horizontal direction above a barrier layer of the high electron mobility transistor, and the gas-sensitive film is deposited between the control gate and the extended gate; the gate of the high electron mobility transistor adopts an extended gate structure to form an electrical contact with the gas-sensitive film; the control gate and the extended gate both form Schottky contact with the barrier layer of the high electron mobility transistor;
[0006] In the working state, a driving voltage is applied to the control gate, the source is grounded, and a drain voltage is applied to the drain; the high electron mobility transistor is used for transduction of sensing signals; the gas-sensitive film assumes the recognition function of gas molecules, and different gas atmospheres are combined with the gate sensitive material, and the gas-sensitive film presents different resistances, so that the extended gate potential changes, resulting in a change in the current in the channel between the drain and the source to realize the sensing function; the source and the drain are used to extract the current signal; the sensing characteristics of the gas sensor in the high electron mobility transistor are regulated by the driving voltage, combined with signal feature engineering and deep learning algorithms to change the specificity of the olfactory sensor chip.
[0007] Further preferably, the materials of the high electron mobility transistor from bottom to top are semi-insulating GaAs substrate, buffer layer, In x Ga 1-x As channel layer and Al x Ga 1-x As barrier layer; control gate and extended gate are deposited directly on Al x Ga 1-x A Schottky contact is formed on the As barrier layer; the source and drain are in ohmic contact.
[0008] Further preferably, the high electron mobility transistor is Al x Ga 1-x N / GaN high electron mobility transistor.
[0009] Further preferably, the gas sensitive film is an oxide or sulfide semiconductor material.
[0010] Further preferably, the gas-sensitive film is SnO2, WO3, ZnO, PbS or SnS2 gas-sensitive film.
[0011] Further preferably, the gas-sensitive film is graphene, MOF, MXene or a composite gas-sensitive material.
[0012] Based on the above-mentioned gate-sensitive field effect transistor olfactory sensor, the present invention provides a corresponding preparation method, comprising the following steps:
[0013] Al2O3 was grown on GaAs substrate by molecular beam epitaxy. 0.3 Ga 0.7 As / In 0.2 Ga 0.8 As heterojunction structure, and then prepare n + The GaAs cap layer forms ohmic contacts for the source and drain;
[0014] The control gate, the extended gate, the source electrode and the drain electrode are prepared by using a photolithography process;
[0015] The gas-sensitive film is deposited between the control gate and the extended gate by using a drop coating, spray coating or spin coating process.
[0016] In general, the above technical solution conceived by the present invention has the following beneficial effects compared with the prior art:
[0017] Compared with the existing electronic nose chip based on semiconductor resistance, the gate-sensitive high electron mobility transistor gas sensor of the present invention has the following advantages: the conductivity of the semiconductor gas-sensitive receptor material and the high electron mobility transistor are spatially separated, the conductive properties of the sensor do not depend on the gas-sensitive material, and the transistor is used for the transduction of the sensing signal, thereby greatly improving the design freedom of the semiconductor gas-sensitive material.
[0018] The transistor in the present invention is a high electron mobility transistor, based on which the sensing signal can be read out and amplified, has the advantages of high saturation operating current, high sensitivity, and high signal-to-noise ratio, works based on a DC drive circuit, has a simple sampling circuit, is easily compatible with CMOS technology, and realizes large-scale array integration.
[0019] In the gate-sensitive field-effect transistor olfactory sensor chip structure proposed in the present invention, the control gate, the extended gate and the high electron mobility transistor barrier layer form a Schottky contact, and there is a parasitic resistance, the control gate, the gas-sensitive film, the extended gate and the high electron mobility transistor source constitute a series resistance divider circuit structure, and the parasitic resistance between the control gate and the extended gate can be designed according to the size and spacing of the extended gate and the control gate electrodes, thereby ensuring that the sensor has an optimal coupling coefficient and operating voltage.
[0020] The gate-sensitive field-effect transistor olfactory sensor proposed in the present invention structurally imitates the olfactory perception neurons of organisms. For the olfactory system of organisms, when odor molecules interact with olfactory receptors on the surface of cilia of olfactory perception neurons, a series of complex chemical processes will be triggered, activating olfactory perception neurons to send odor signals, which will be integrated into the olfactory bulb and then projected into the olfactory cortex, thereby triggering the sense of smell. The gate-sensitive material of the high electron mobility transistor provided by the present invention corresponds to the biological olfactory receptors. When the gas molecules combine with the gate-sensitive material, the resistance of the gate-sensitive film changes. The present invention utilizes the Schottky gate resistance effect to construct a gate series resistance voltage divider circuit, and couples the electrical signal changes caused by the gas-solid interaction process into the changes in the gate potential, thereby regulating the channel 2EDG concentration, so that the olfactory sensor generates a "nerve impulse", and the electrical signal is conducted by the source and drain electrodes. In addition, the sensing characteristics of the sensor proposed in the present invention can be regulated by the gate voltage, and further combined with signal feature engineering and deep learning algorithms, the specificity of the olfactory sensor chip can be improved. BRIEF DESCRIPTION OF THE DRAWINGS
[0021] Figure 1 is a schematic diagram of the three-dimensional structure of a gate-sensitive field-effect transistor olfactory sensor provided by an embodiment of the present invention;
[0022] Figure 2 is a transfer characteristic curve of the olfactory sensor chip provided by an embodiment of the present invention in NO2 gas with different concentrations;
[0023] Figure 3 1 is a response curve of the olfactory sensor chip provided by an embodiment of the present invention to NO2 gas at different gate voltages;
[0024] Figure 4 It is a principal component analysis diagram of the first two principal components of the response characteristics of the olfactory sensor provided by an embodiment of the present invention to different concentrations of NO and NO2;
[0025] Marking Description:
[0026] 1- high electron mobility transistor; 2- control gate; 3- gas sensitive film; 4- extended gate; 5- source; 6- drain. DETAILED DESCRIPTION
[0027] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention 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 invention and are not intended to limit the present invention.
[0028] Figure 1 3D schematic diagram of the gate-sensitive field effect transistor olfactory sensor provided by an embodiment of the present invention, comprising: a high electron mobility transistor 1 and a gas-sensitive film 3; the high electron mobility transistor 1 comprises a source 5, a drain 6 and a gate; wherein the gate of the high electron mobility transistor 1 comprises a control gate 2 and an extended gate 4; the control gate 2 and the extended gate 4 are located in the horizontal direction of the barrier layer of the high electron mobility transistor 1, and the gas-sensitive film 3 is deposited between the control gate 2 and the extended gate 4; the control gate, the extended gate and the Al x Ga 1-x The contacts of the As barrier layer are all Schottky contacts; the high electron mobility transistor 1 is used for transduction of the sensing signal; a gate voltage is applied to the control gate 2 as a driving voltage; the gas sensitive film 3 is used for identification of gas molecules; the source 5 and the drain 6 are used for extracting the current signal.
[0029] In the embodiment of the present invention, the materials of the high electron mobility transistor from bottom to top are a semi-insulating GaAs substrate, a buffer layer, an In x Ga 1-x As channel layer and Al x Ga 1-x As barrier layer; control gate and extended gate are deposited directly on Al x Ga 1-xAs barrier layer, a Schottky contact is formed; the source and drain are ohmic contacts. The high electron mobility transistor in the present invention can also be Al x Ga 1-x N / GaN high electron mobility transistor;
[0030] The gas-sensitive film may be an oxide or sulfide semiconductor material, for example, the gas-sensitive film may be SnO2, WO3, ZnO, PbS or SnS2 gas-sensitive film; the gas-sensitive material may also be graphene, MOF, MXene or a composite gas-sensitive material;
[0031] The extended gate 4 connects the high electron mobility transistor 1 to one end of the gas-sensitive film to form a series structure. The other end of the gas-sensitive film is called a control gate. The control gate applies a gate voltage (driving voltage). The source of the field effect transistor is grounded, and the drain voltage is applied to the drain.
[0032] When the gas-sensitive film is exposed to a specific atmosphere, its resistance changes, and the voltage division of the series structure changes, causing the extended gate potential of the field effect tube to change, thereby changing the current in the channel between the drain and the source, thus realizing the sensing function;
[0033] It should be noted that the leakage current of the field effect transistor satisfies the following relationship:
[0034]
[0035]
[0036] Among them, I D is the leakage current; V th is the threshold voltage; V DS is the voltage between the drain and the source; V CG is the voltage applied to the control gate; V EG is the potential of the extended gate; β is related to the electrical conduction capability of the gate-sensitive field effect transistor itself; R0 is the parasitic resistance between the control gate 2 and the extended gate 4; R s is the resistance of the gas sensitive film; R GS To extend the resistance between gate and source;
[0037] When the gas-sensitive material is not deposited, there is a parasitic resistance R0 between the control gate 2 and the extended gate 4. According to formula (2), V CG 、V EG With R0, R s and R GS The coupling ratio is related to the semiconductor resistance film structure R at room temperature. s Much larger than R GS , when the parasitic resistance R0 is large, in order to make V EGIn the subthreshold swing region to improve the sensitivity of the sensor, the voltage V applied to the control gate CG Need to be very high, which is not conducive to the stability of the sensor. R0 and R GS The size of can be adjusted through the preparation process and electrode size design, so as to ensure that the sensor has a high sensitivity while making the driving voltage V CG Work within reason.
[0038] The preparation method of the gate-sensitive field effect transistor olfactory sensor is as follows:
[0039] (1) Fabrication of high electron mobility transistors by using molecular beam epitaxy (MBE) to grow Al on GaAs substrates 0.3 Ga 0.7 As / In 0.2 Ga 0.8 As heterojunction structure, and then prepare n + The GaAs cap layer forms ohmic contacts for the source and drain, and the control gate, extended gate, source and drain are prepared by photolithography;
[0040] (2) depositing a PbS quantum dot gas-sensitive film between the control gate and the extended gate by a drop coating, spray coating or spin coating process;
[0041] (3) The electrical characteristics of the olfactory sensor chip in a NO2 atmosphere were measured using a semiconductor parameter tester, an atmosphere detection station, and a gas mixing system. Figure 2 The transfer characteristic curve of the olfactory sensor chip in different NO2 gas concentrations. As the NO2 gas concentration increases, the threshold voltage of the field effect transistor shifts positively.
[0042] (4) By controlling the driving voltage to regulate the working current of the olfactory sensor, the sensor can be operated in different ranges, such as Figure 3 As shown, when the negative gate voltage is larger, the leakage current decreases rapidly. Although the change of the leakage current is small, the relative change ratio is larger. If the sampling accuracy of the sampling circuit is met, the sensitivity of the sensor will be higher.
[0043] (5) Based on the olfactory sensor testing of different concentrations of NO2, the response curve was feature extracted, mainly including the maximum response value, the integral area of the response stage, the integral area of the recovery stage and the differential extreme value of the response curve, and then the response characteristics were subjected to principal component analysis (PCA); Figure 4 The relationship between the one-dimensional principal component data of the sensor response characteristics under different gate voltages and the NO2 gas concentration can be found to satisfy the ideal power exponential relationship, and the NO2 concentration can be further calibrated and quantitatively analyzed.
[0044] In summary, compared with the prior art, the present invention has the following advantages:
[0045] Compared with the existing electronic nose chip based on semiconductor resistance, the gate-sensitive high electron mobility transistor gas sensor of the present invention has the following advantages: the conductivity of the semiconductor gas-sensitive receptor material and the high electron mobility transistor are spatially separated, the conductive properties of the sensor do not depend on the gas-sensitive material, and the transistor is used for the transduction of the sensing signal, thereby greatly improving the design freedom of the semiconductor gas-sensitive material.
[0046] The transistor in the present invention is a high electron mobility transistor, based on which the sensing signal can be read out and amplified, has the advantages of high saturation operating current, high sensitivity, and high signal-to-noise ratio, works based on a DC drive circuit, has a simple sampling circuit, is easily compatible with CMOS technology, and realizes large-scale array integration.
[0047] In the gate-sensitive field-effect transistor olfactory sensor chip structure proposed in the present invention, the control gate, the extended gate and the high electron mobility transistor barrier layer form a Schottky contact, and there is a parasitic resistance, the control gate, the gas-sensitive film, the extended gate and the high electron mobility transistor source constitute a series resistance divider circuit structure, and the parasitic resistance between the control gate and the extended gate can be designed according to the size and spacing of the extended gate and the control gate electrodes, thereby ensuring that the sensor has an optimal coupling coefficient and operating voltage.
[0048] The gate-sensitive field-effect transistor olfactory sensor proposed in the present invention structurally imitates the olfactory perception neurons of organisms. For the olfactory system of organisms, when odor molecules interact with olfactory receptors on the surface of cilia of olfactory perception neurons, a series of complex chemical processes will be triggered, activating olfactory perception neurons to send odor signals, which will be integrated into the olfactory bulb and then projected into the olfactory cortex, thereby triggering the sense of smell. The gate-sensitive material of the high electron mobility transistor provided by the present invention corresponds to the biological olfactory receptors. When the gas molecules combine with the gate-sensitive material, the resistance of the gate-sensitive film changes. The present invention utilizes the Schottky gate resistance effect to construct a gate series resistance voltage divider circuit, and couples the electrical signal changes caused by the gas-solid interaction process into the changes in the gate potential, thereby regulating the channel 2EDG concentration, so that the olfactory sensor generates a "nerve impulse", and the electrical signal is conducted by the source and drain electrodes. In addition, the sensing characteristics of the sensor proposed in the present invention can be regulated by the gate voltage, and further combined with signal feature engineering and deep learning algorithms, the specificity of the olfactory sensor chip can be improved.
[0049] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.
Claims
1. A gate-sensitive field effect transistor olfactory sensor, characterized in that: Its structure simulates biological olfactory neurons, including high electron mobility transistors and gas-sensitive films. The gate of the high electron mobility transistor includes a control gate and an extended gate, and the gas-sensitive film between the two serves as an odor receptor. The control gate and the extended gate are located in a horizontal direction above the barrier layer of the high electron mobility transistor, and a gas-sensitive film is deposited between the control gate and the extended gate; the gate of the high electron mobility transistor forms an electrical contact with the gas-sensitive film using an extended gate structure; the control gate and the extended gate both form Schottky contacts with the barrier layer of the high electron mobility transistor, and a gate series resistor voltage divider circuit is constructed using the Schottky gate resistance effect; In the working state, a driving voltage is applied to the control gate; the source of the high electron mobility transistor is grounded, and a drain voltage is applied to the drain; The high electron mobility transistor is used for transduction of sensing signals; the gas-sensitive film assumes the function of identifying gas molecules. Different gas atmospheres are combined with gate sensitive materials, and the gas-sensitive film presents different resistances, so that the extended gate potential changes, resulting in a change in the current in the channel between the drain and the source to achieve the sensing function; the source and the drain are used to extract the current signal; the sensing characteristics of the gas sensor in the high electron mobility transistor are regulated by the driving voltage, combined with signal feature engineering and deep learning algorithms to change the specificity of the olfactory sensor chip; Among them, the leakage current is: Among them, I D is the leakage current; V th is the threshold voltage; V DS is the voltage between the drain and the source; V CG is the voltage applied to the control gate; V EG is the potential of the extended gate; β is related to the electrical conduction capability of the gate-sensitive field-effect transistor itself; R0 is the parasitic resistance between the control gate and the extended gate; R s is the resistance of the gas sensitive film; R GS To extend the resistance between gate and source.
2. The gate-sensitive field effect transistor olfactory sensor according to claim 1, characterized in that: The materials of the high electron mobility transistor from bottom to top are semi-insulating GaAs substrate, buffer layer, In x Ga 1-x As channel layer and Al x Ga 1-x As barrier layer; the control gate and the extended gate are directly deposited on the Al x Ga 1-x A Schottky contact is formed on the As barrier layer; the source and drain are in ohmic contact.
3. The gate-sensitive field effect transistor olfactory sensor according to claim 1, characterized in that: The high electron mobility transistor is Al x Ga 1-x N / GaN high electron mobility transistor.
4. The gate-sensitive field effect transistor olfactory sensor according to any one of claims 1 to 3, characterized in that: The gas-sensitive film is made of oxide or sulfide semiconductor material.
5. The gate-sensitive field effect transistor olfactory sensor according to claim 4, characterized in that: The gas-sensitive film is SnO2, WO3, ZnO, PbS or SnS2 gas-sensitive film.
6. The gate-sensitive field effect transistor olfactory sensor according to any one of claims 1 to 3, characterized in that: The gas-sensitive film is graphene, MOF, MXene or a composite gas-sensitive material.
7. A method for preparing a gate-sensitive field effect transistor olfactory sensor according to claim 2, characterized in that: The following steps are involved: Al2O3 was grown on GaAs substrate by molecular beam epitaxy. 0.3 Ga 0.7 As / In 0.2 Ga 0.8 As heterojunction structure, and then prepare n + The GaAs cap layer forms ohmic contacts for the source and drain; The control gate, the extended gate, the source electrode and the drain electrode are prepared by using a photolithography process; The gas-sensitive film is deposited between the control gate and the extended gate by using a drop coating, spray coating or spin coating process.