CN116773636A - Field effect tube type gas sensor and preparation method and application thereof - Google Patents
Field effect tube type gas sensor and preparation method and application thereof Download PDFInfo
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Abstract
The invention belongs to the technical field of microelectronic materials, and particularly relates to a field effect tube type gas sensor and a preparation method and application thereof. The sensitive material in the field effect tube type gas sensor is made of graphene and a multi-element metal ultrathin layer deposited on the surface of the graphene, and the device is designed into a field effect tube structure with a back gate electrode, so that the response performance and the recovery speed of the device to gas can be enhanced simultaneously, the device also has more flexible manual regulation and control capability, and the application scene of the sensor is widened.
Description
Technical Field
The invention belongs to the technical field of microelectronic devices. More particularly, to a field effect tube type gas sensor, and a preparation method and application thereof.
Background
With the continuous progress of the internet of things technology, the gas sensor is widely applied to the fields of environmental monitoring, intelligent home and the like. Not only is the performance requirement on the gas sensor higher and higher, but also the gas sensor is required to have stronger miniaturized integration capability. Currently, gas sensors use more sensitive materials, mainly metal oxide semiconductor or organic semiconductor materials. The reaction of conventional thick film mos sensors with the gas to be inspected at room temperature proceeds very slowly, usually requiring preheating and operation at higher temperatures. For example, chinese patent application CN111656172A discloses NO x A sensing device comprises a substrate, a dielectric layer on the substrate, and a heater in the dielectric layer, wherein the gas sensitive material is aluminum oxide (Al 2 O 3 ) Doped conductive metal oxide, the sensing device has lower power consumption and higher efficiency than prior art sensing devices, such low operating temperatures also reduce the presence of siloxane in the device and thus reduce the likelihood of the sensing device being poisoned by siloxane, but the sensor still needs to operate at 200 ℃. On the other hand, the manufacturing process of the traditional thick film metal oxide semiconductor gas sensor has a certain difficulty in realizing further miniaturization on the basis of compatibility, so that the manufacturing cost is increased.
The graphene has the characteristics of large specific surface area, extremely high carrier mobility, small intrinsic noise, easiness in chemical modification, flexibility, convenience in integration and the like, and has a good application prospect in the field of high-performance room-temperature gas sensor development. However, the response of the graphene-based gas sensor to ammonia is generally weak, and the surface of the intrinsic graphene film can be subjected to ozone treatment through researches; or oxygen-containing groups are introduced on the surface of the graphene film by a chemical method; or the graphene film is subjected to graphical processing to introduce a defective edge to increase the active position of gas adsorption, and the like, so that the response strength of the graphene-based gas sensor to ammonia gas is improved. And the methods often have the defects of reducing the carrier mobility of the graphene film, increasing noise, increasing manufacturing cost and the like. The modification of the graphene surface with a material having a catalytic effect is also a method for improving the response strength of graphene to a specific gas. But generally adopts a single catalytic material, is prepared by a chemical method, needs a plurality of oxidation-reduction reactions, relates to a sol-gel method, a hydrothermal method and the like, and has a complex manufacturing process; on the other hand, graphene-based gas sensors often require a longer recovery time while achieving a higher response strength, and sometimes even require high temperature or ultraviolet light irradiation to assist in recovery, so that the use of the sensors is limited.
Therefore, how to improve the response performance and shorten the recovery time is the key point and the difficulty of the development of the graphene-based gas sensor.
Disclosure of Invention
The invention aims to overcome the defects that the existing graphene-based gas sensor is difficult to improve response performance and shorten recovery time, and provides a field effect tube type gas sensor.
Another object of the invention is to provide a method for manufacturing the field effect tube type gas sensor.
It is another object of the invention to provide the use of said field effect tube type gas sensor.
The above object of the present invention is achieved by the following technical scheme:
the invention also protects a field effect tube type gas sensor, which comprises a sensitive material;
wherein the sensitive material consists of a graphene film and a metal film deposited on the graphene film;
preferably, the metal film is any two or more of gold, platinum, palladium and silver.
More preferably, the metal film is a combination of gold and platinum.
Preferably, the metal thin film is deposited in order of low to high melting temperature of the metal.
Preferably, the thickness of each of the metal thin film layers is 0.5 to 1nm. The thickness of the metal film layer should not be too thick, and the thickness of each layer should not exceed 1nm, otherwise the device performance will be greatly attenuated.
Specifically, the field effect tube type gas sensor comprises a doped semiconductor substrate, an insulating layer, a back gate electrode, a graphene film, a source electrode, a drain electrode and a metal film from bottom to top;
the insulating layer is arranged on the surface of the doped semiconductor substrate;
the back gate electrode is arranged on the surface of the insulating layer, and the bottom of the back gate electrode is in contact with the doped semiconductor;
the graphene film is arranged on the surface of the insulating layer and is spaced from the back gate electrode;
the source electrode and the drain electrode are respectively arranged at two ends of the graphene film;
the metal thin film is disposed in a graphene film region formed between the source electrode and the drain electrode.
The invention also provides a preparation method of the field effect tube type gas sensor, which comprises the following steps:
s1, adopting a doped semiconductor substrate, wherein the surface of the substrate is provided with an insulating layer, removing part of the insulating layer, and manufacturing a back gate electrode on the substrate with the insulating layer removed, so that the bottom of the back gate electrode is contacted with the doped semiconductor substrate through a removed insulating layer region; wherein the area from which the portion of the insulating layer is removed may be determined according to common general knowledge of a person skilled in the art.
S2, transferring or depositing the graphene film on the surface of the insulating layer, and separating the graphene film from the back gate electrode; the back gate electrode can also adopt a surrounding back gate, and the surrounding back gate is beneficial to strengthening the regulation and control capability of the back gate, is beneficial to uniform distribution of the electric potential of the graphene film region, and ensures that the modulation degree is more uniform;
s3, patterning the graphene film, removing redundant parts of the graphene film, and reserving the source electrode, the drain electrode and the graphene film in the area between the source electrode and the drain electrode;
s4, respectively preparing a source electrode and a drain electrode at two ends of the surface of the graphene film obtained in the step S3;
and S5, sequentially depositing metal on the surface of the graphene film between the source electrode and the drain electrode, and cleaning the surface to obtain the field effect tube type gas sensor.
Further, in step S1, the doped semiconductor has a resistivity of (1 to 5). Times.10 -3 Omega cm. Preferably, the semiconductor is silicon, silicon carbide, sapphire or silicon nitride.
Preferably, the insulating layer is SiO 2 、Al 2 O 3 Or HaO 2 . Different insulating layer materials are selected, and different thicknesses can be set according to the properties of the insulating layer. In general, a material with a larger dielectric constant is used as an insulating layer, and a thinner thickness can be adopted on the basis of ensuring good insulativity, so that on one hand, the regulation capability of the back gate can be enhanced, on the other hand, the material also has better response performance under lower back gate voltage, and the lower back gate voltage can reduce the power consumption of the system.
Preferably, the graphene film is prepared by a chemical vapor deposition method. Compared with chemical preparation methods such as oxidation reduction, the graphene prepared by a chemical vapor deposition method has better conductivity; compared with the mechanical stripping preparation method, the chemical vapor deposition method has high efficiency and low cost, is easy to be compatible with the preparation process of the semiconductor device, and is beneficial to device integration.
Preferably, the deposited metal is deposited by an electron beam evaporation method.
Further, the vacuum degree of the deposition chamber of the electron beam evaporation device reaches 10 -7 the deposition of metal is started after torr magnitude; the rate of depositing the metal isCompared with a magnetron sputtering method, the method for depositing metal by adopting electron beam evaporation has less damage to the surface of the graphene, and is beneficial to maintaining the high mobility of the graphene; compared with a chemical method, the method has less pollution to the surface of the graphene, and is favorable for the stability of the performance of the device.
The invention also provides application of the field effect tube type gas sensor in gas detection.
More preferably, the gas is ammonia, hydrogen sulfide or carbon monoxide.
Most preferably, the gas is ammonia.
The invention has the following beneficial effects: the invention provides a field effect tube type gas sensor, sensitive materials in the field effect tube type gas sensor are made of graphene and metal deposited on the surface of the graphene, and the device is designed into a field effect tube structure with a back gate electrode, so that the response performance and the recovery speed of the device to gas can be enhanced simultaneously, the device also has artificial regulation and control capability, the application scene of the sensor is widened, and the application scene of the sensor is widened
Drawings
Fig. 1 is a schematic structural diagram of a graphene-based field effect tube type gas sensor prepared in embodiment 1 and embodiment 2, wherein a cross-sectional view is a schematic structural diagram of a device connected to a power supply, and a top view is a structural diagram of a device not connected to the power supply.
Fig. 2 is a schematic structural diagram of a graphene-based field effect tube type gas sensor prepared in example 3.
FIG. 3 is a statistical plot of response data of different gas sensors to 200ppm ammonia at room temperature.
FIG. 4 is a graph showing statistics of response data (a) of the Pt/Au/Gr device obtained in example 1 to ammonia gas of different concentrations at room temperature and a graph showing statistics of cycle data (b) of continuous 5 responses of the device to ammonia gas of 12ppm at room temperature.
Detailed Description
The invention is further illustrated in the following drawings and specific examples, which are not intended to limit the invention in any way. Unless specifically stated otherwise, the reagents, methods and apparatus employed in the present invention are those conventional in the art.
Reagents and materials used in the following examples are commercially available unless otherwise specified.
The P-type heavily doped silicon substrates used in examples 1 to 3 and comparative examples 1 to 3 had a resistivity R of 3×10 -3 Ω.cm。
Example 1 preparation of graphene-based field effect tube type gas sensor
S1, providing SiO with 300nm thick surface 2 P-type of layerAnd (3) manufacturing a metal alignment mark for alignment on the surface of the heavily doped silicon substrate, wherein Cr and Au are selected as metal alignment mark materials, and in the specific manufacturing process, an 8nm thick Cr layer is firstly deposited by an electron beam evaporation device, and then an 80nm thick Au layer is deposited. The metal alignment mark is used for alignment in the manufacturing process of the device, and does not belong to the device structure and does not need to be removed.
S2, forming SiO to be etched in a specific area of the substrate through an overlay process 2 Then removing SiO on the surface of the region (500 um x 500um in area) by a reactive ion etching process 2 The etching gas is CHF 3 And CF (compact F) 4 The flow rates of the two are 20sccm and 30sccm respectively, the air pressure is 5Pa, the radio frequency power is 400W, and the etching time is 5 minutes.
S3, removing the SiO through an overlay process 2 A back gate electrode is prepared by an electron beam evaporation process over the region of (a). For ease of testing, the area of the individual electrodes may be set to 4mm 2 。
S4, cleaning the surface of the substrate, and transferring the graphene film prepared by the CVD method to the surface of the substrate. The transfer method comprises the steps of shearing copper foil with a specific area and a graphene film growing on one side, and spin-coating polymethyl methacrylate (PMMA) with a specific thickness (0.4 um) on the surface with the graphene growing on the copper foil through a spin coater; the sample was placed in FeCl with the PMMA layer facing upward 3 In the solution, copper on the copper foil is completely corroded; taking out the sample, cleaning and soaking in acetone solution, and completely dissolving the PMMA layer; and finally, taking out the graphene from the acetone solution by using the target substrate, and further cleaning the surface of the sample.
And S5, carrying out patterning treatment on the graphene film through an overlay process to form a graphene region comprising a device channel and being in contact with the metal electrode. And removing the grapheme outside the region by a reactive ion etching process, wherein the etching gas is O 2 The flow is 20sccm, the air pressure is 5Pa, the radio frequency power is 100W, and the etching time is 8 seconds.
S6, manufacturing a metal electrode pair with a specific distance above the graphene region, wherein the distance can be set to be 2mm, and the electrode materials are Cr and Au to form a source electrode of the deviceIn the specific manufacturing of the drain electrode, an 8nm thick Cr layer is deposited firstly by an electron beam evaporation device, and then an 80nm thick Au layer is deposited, so that the area of a single electrode can be set to be 4mm for the convenience of testing 2 。
S7, sequentially depositing 0.5nm Au and 0.5nm Pt ultrathin layers in the graphene channel region through an electron beam evaporation process. To the pressure of the electron beam evaporation chamber is reduced to 10 -7 the deposition process is started after the torr magnitude; au is deposited first, followed by Pt. The deposition rate of each metal wasThe final device is named as Pt/Au/Gr device, the structure of the device is shown in figure 1, it is to be noted that the device is not provided with a circuit on the upper side, and the circuit schematic diagram of the device is connected above the device when the device is used for testing, so as to clarify how the device is used when the device is tested.
Example 2 preparation of graphene-based field effect tube type gas sensor
Example 2 differs from example 1 in that in step S1, 300nm thick SiO was selected 2 The layer is replaced by 20-60 nm Al 2 O 3 As a gate insulating layer; in step S2, al on the surface of the region (500 um×500 um) is removed by wet etching 2 O 3 A layer. The wet etch used a 100:1 HF solution (etch rate of about 0.6 nm/sec).
Other parameters and steps refer to example 1. The resulting device structure was the same as in example 1.
Example 3 preparation of graphene-based field effect tube type gas sensor
Example 3 differs from example 1 in that in step S2, siO is etched 2 The back gate electrode obtained in step S3 is in a surrounding shape.
Other parameters and steps refer to example 1. The resulting device structure is shown in fig. 2.
Comparative example 1 preparation of graphene-based field effect tube type gas sensor
Comparative example 1 differs from example 1 in that the graphene surface was not deposited with any metal, and the resulting device was named Gr device.
The preparation method specifically comprises the following steps:
s1, providing SiO with 300nm thick surface 2 The P-type heavily doped silicon substrate of the layer is provided with a metal alignment mark for alignment, cr and Au are selected as metal alignment mark materials, and in the specific manufacturing process, an 8nm thick Cr layer is firstly deposited by an electron beam evaporation device, and then an 80nm thick Au layer is deposited.
S2, forming SiO to be etched in a specific area of the substrate through an overlay process 2 Then removing SiO on the surface of the region (500 um x 500um in area) by a reactive ion etching process 2 The etching gas is CHF 3 And CF (compact F) 4 The flow rates of the two are 20sccm and 30sccm respectively, the air pressure is 5Pa, the radio frequency power is 400W, and the etching time is 5 minutes.
S3, removing the SiO through an overlay process 2 A back gate electrode is prepared by an electron beam evaporation process over the region of (a). For ease of testing, the area of the individual electrodes may be set to 4mm 2 。
S4, cleaning the surface of the substrate, and transferring the graphene film prepared by the CVD method to the surface of the substrate. The transfer method comprises the steps of shearing copper foil with a specific area and a graphene film growing on one side, and spin-coating polymethyl methacrylate (PMMA) with a specific thickness (0.4 um) on the surface with the graphene growing on the copper foil through a spin coater; the sample was placed in FeCl with the PMMA layer facing upward 3 In the solution, copper on the copper foil is completely corroded; taking out the sample, cleaning and soaking in acetone solution, and completely dissolving the PMMA layer; and finally, taking out the graphene from the acetone solution by using the target substrate, and further cleaning the surface of the sample.
And S5, carrying out patterning treatment on the graphene film through an overlay process to form a graphene region comprising a device channel and being in contact with the metal electrode, and removing graphene outside the region through a reactive ion etching process. Wherein the etching gas is O 2 The flow is 20sccm, the air pressure is 5Pa, the radio frequency power is 100W, and the etching time is 8 seconds.
S6, preparing above the graphene regionThe metal electrode pair with specific spacing can be set to 2mm, the electrode materials are Cr and Au, so as to form the source electrode and the drain electrode of the device, in the concrete, the electron beam evaporation equipment is used for depositing Cr layer with the thickness of 8nm firstly, then depositing Au layer with the thickness of 80nm, and for the convenience of test, the area of a single electrode can be set to 4mm 2 。
Comparative example 2 preparation of graphene-based field effect tube type gas sensor
Comparative example 2 differs from example 1 in that the graphene surface alone deposited with only 1nm thick Au, the resulting device was designated as Au/Gr device.
The preparation method specifically comprises the following steps:
s1, providing SiO with 300nm thick surface 2 The P-type heavily doped silicon substrate of the layer is provided with a metal alignment mark for alignment, cr and Au are selected as metal alignment mark materials, and in the specific manufacturing process, an 8nm thick Cr layer is firstly deposited by an electron beam evaporation device, and then an 80nm thick Au layer is deposited.
S2, forming SiO to be etched in a specific area of the substrate through an overlay process 2 Then removing SiO on the surface of the region (500 um x 500um in area) by a reactive ion etching process 2 The etching gas is CHF 3 And CF (compact F) 4 The flow rates of the two are 20sccm and 30sccm respectively, the air pressure is 5Pa, the radio frequency power is 400W, and the etching time is 5 minutes.
S3, removing the SiO through an overlay process 2 A back gate electrode is prepared by an electron beam evaporation process over the region of (a). For ease of testing, the area of the individual electrodes may be set to 4mm 2 。
S4, cleaning the surface of the substrate, and transferring the graphene film prepared by the CVD method to the surface of the substrate. The transfer method comprises cutting copper foil with graphene film grown on one side of specific area, spin-coating polymethyl methacrylate (PMMA) with specific thickness (such as 0.4 um) on one side of graphene film grown on the copper foil by a spin coater; the sample was placed in FeCl with the PMMA layer facing upward 3 In the solution, copper on the copper foil is completely corroded; taking out the sample, cleaning and soaking in acetone solution, and completely dissolving the PMMA layer; finally useAnd fishing out the graphene from the acetone solution by the target substrate, and further cleaning the surface of the sample.
And S5, carrying out patterning treatment on the graphene film through an overlay process to form a graphene region comprising a device channel and being in contact with the metal electrode. And removing the grapheme outside the region by a reactive ion etching process, wherein the etching gas is O 2 The flow is 20sccm, the air pressure is 5Pa, the radio frequency power is 100W, and the etching time is 8 seconds.
S6, manufacturing a metal electrode pair with a specific distance above a graphene region, wherein the distance can be set to be 2mm, cr and Au are selected as electrode materials to form a source electrode and a drain electrode of the device, in the specific manufacturing process, an 8nm thick Cr layer is firstly deposited by an electron beam evaporation device, then an 80nm thick Au layer is deposited, and for convenience in testing, the area of a single electrode can be set to be 4mm 2 。
S7, depositing an Au ultrathin layer with the thickness of 0.5nm in the graphene channel region through an electron beam evaporation process. To the pressure of the electron beam evaporation chamber is reduced to 10 -7 the deposition process is started after torr magnitude is reachedAu is deposited at a deposition rate of (a).
Comparative example 3 preparation of graphene-based field effect tube type gas sensor
Comparative example 2 differs from example 1 in that the graphene surface alone deposits only 1nm thick Pt, and the resulting device is referred to as a Pt/Gr device.
The preparation method specifically comprises the following steps:
s1, providing SiO with 300nm thick surface 2 The P-type heavily doped silicon substrate of the layer is provided with a metal alignment mark for alignment, cr and Au are selected as metal alignment mark materials, and in the specific manufacturing process, an 8nm thick Cr layer is firstly deposited by an electron beam evaporation device, and then an 80nm thick Au layer is deposited.
S2, forming SiO to be etched in a specific area of the substrate through an overlay process 2 Then removing SiO on the surface of the region (500 um x 500um in area) by a reactive ion etching process 2 The etching gas is CHF 3 And CF (compact F) 4 The flow rates of the two are 20sccm and 30sccm respectively, the air pressure is 5Pa, the radio frequency power is 400W, and the etching time is 5 minutes.
S3, removing the SiO through an overlay process 2 A back gate electrode is prepared by an electron beam evaporation process over the region of (a). For ease of testing, the area of the individual electrodes may be set to 4mm 2 。
S4, cleaning the surface of the substrate, and transferring the graphene film prepared by the CVD method to the surface of the substrate. The transfer method comprises cutting copper foil with graphene film grown on one side of specific area, spin-coating polymethyl methacrylate (PMMA) with specific thickness (such as 0.4 um) on one side of graphene film grown on the copper foil by a spin coater; the sample was placed in FeCl with the PMMA layer facing upward 3 In the solution, copper on the copper foil is completely corroded; taking out the sample, cleaning and soaking in acetone solution, and completely dissolving the PMMA layer; and finally, taking out the graphene from the acetone solution by using the target substrate, and further cleaning the surface of the sample.
And S5, carrying out patterning treatment on the graphene film through an overlay process to form a graphene region comprising a device channel and being in contact with the metal electrode. And removing the grapheme outside the region by a reactive ion etching process, wherein the etching gas is O 2 The flow is 20sccm, the air pressure is 5Pa, the radio frequency power is 100W, and the etching time is 8 seconds.
S6, manufacturing a metal electrode pair with a specific distance above a graphene region, wherein the distance can be set to be 2mm, cr and Au are selected as electrode materials to form a source electrode and a drain electrode of the device, in the specific manufacturing process, an 8nm thick Cr layer is firstly deposited by an electron beam evaporation device, then an 80nm thick Au layer is deposited, and for convenience in testing, the area of a single electrode can be set to be 4mm 2 。
S7, depositing a 0.5nm Pt ultrathin layer in the graphene channel region through an electron beam evaporation process. To the pressure of the electron beam evaporation chamber is reduced to 10 -7 the deposition process is started after torr magnitude is reachedPt is deposited at a deposition rate of (a).
Analysis of results
In order to ensure good insulation, the substrates of the devices obtained in example 1 and comparative examples 1 to 3 were selected from SiO having a thickness of 300nm on the surface 2 The corresponding value of the modulated back gate voltage is higher. The channel region contained only a pure CVD graphene film, the corresponding device was called a Gr device (comparative example 1); devices with 1nm thick Au alone or 1nm thick Pt alone deposited on the graphene channel surface were referred to as Au/Gr (comparative example 2) and Pt/Gr devices (comparative example 3), respectively; the device with 0.5nm Au+0.5nm Pt deposited on the graphene channel surface was referred to as a Pt/Au/Gr device (example 1).
(1) Response performance analysis of device to 200ppm ammonia at room temperature
FIG. 3 compares the devices obtained in example 1 and comparative examples 1-3 with a 200X 10 open for 3 minutes under different back gate voltages -6 Room temperature response of ammonia gas at a concentration (i.e., 200 ppm). Taking the relative change rate delta I/I of the current of the device 0 In response to the device, where I 0 Is the stable current of the device when ammonia is not introduced. As can be seen from fig. 3, at zero backgate voltage, the responses of the Gr device, au/Gr device, pt/Gr device, and Pt/Au/Gr device were-1.5%, -10.51%, -17.53%, and-11.03%, respectively. The response of devices with deposited Au or Pt ultra-thin layers is significantly enhanced compared to Gr devices, but the recovery performance is not significantly improved. Changing back grid voltage V GS After that, au/Gr devices, pt/Gr devices and Pt/Au/Gr devices show different trends.
For Au/Gr devices, the backgate voltage V is shown in FIG. 3b and Table 2 GS The method has a certain forward modulation effect on the response intensity, but has no obvious modulation effect on the recovery speed.
For a Pt// Gr device, the backgate voltage V is shown in FIG. 3c and Table 2 GS There is no modulation effect on its response intensity at all, but there is a significant forward modulation effect on the recovery rate.
For Pt/Au/Gr devices, the back gate voltage V is shown in FIG. 3d, table 1 and Table 2 GS The method has obvious forward modulation effect on the response strength and the recovery speed, the response time is smaller than that of an Au/Gr device and a Pt// Gr device in the range of 0-60V, and the response performance is obviously improved.
Example 2The performance of the device obtained in example 3 is similar to that of a Pt/Au/Gr device, the response performance (comprising the two aspects of improving the response strength and shortening the response time) and the recovery speed of the device to gas can be simultaneously enhanced, and the device has the artificial regulation capability and can be used for different back grid voltages V GS And has different response strengths.
In addition, the material of the insulating layer used in example 2 was Al 2 O 3 ，Al 2 O 3 Compared with SiO 2 The dielectric constant is larger, so that the thickness can be thinner on the basis of ensuring good insulativity, on one hand, the regulation capability of the back gate can be enhanced, on the other hand, the back gate has better response performance under lower back gate voltage, and the lower back gate voltage can reduce the system power consumption.
The device obtained in example 3 uses a wrap-around back gate and the SiO is etched in the fabrication step S2 2 The back gate electrode is also correspondingly shaped in a circle in step S3. The surrounding back gate is beneficial to strengthening the regulation and control capability of the back gate, is beneficial to uniform distribution of the channel region potential, and ensures that the modulation degree is more uniform.
Table 1 three devices for 200ppm NH at different backgate voltages 3 Room temperature response time of gas
Table 2 three devices for 200ppm NH at different backgate voltages 3 Recovery time of gas room temperature response
(2) Response performance analysis of device to ammonia with different concentrations at room temperature
As shown in fig. 4, fig. 4 (a) shows that the Pt/Au/Gr device obtained in example 1 has a response to the introduction of ammonia gas at a concentration of 12ppm, 25ppm, 50ppm, 100ppm and 200ppm for 3 minutes at room temperature, respectively, -6.43%, -7.56%, -9.7%, -12.25% and-16.18% at a back gate voltage of 60V, indicating that the Pt/Au/G device also has a better response strength to ammonia gas at a lower concentration. FIG. 4 (b) shows the response of the Pt/Au/Gr device obtained in example 1 to five consecutive test cycles of 12ppm ammonia at room temperature, indicating better repeatability of the Pt/Au/G device.
The above examples are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above examples, and any other changes, modifications, substitutions, combinations, and simplifications that do not depart from the spirit and principle of the present invention should be made in the equivalent manner, and the embodiments are included in the protection scope of the present invention.
Claims (10)
1. A field effect tube type gas sensor, characterized in that the field effect tube type gas sensor comprises a sensitive material;
wherein the sensitive material consists of a graphene film and a metal film deposited thereon.
2. The field effect tube type gas sensor according to claim 1, wherein the metal thin film is any two or more of gold, platinum, palladium, silver.
3. The field effect tube gas sensor of claim 2, wherein the metal film is a combination of gold and platinum.
4. The field effect tube type gas sensor according to claim 1, wherein the metal thin film is deposited in order of low to high melting temperature of the metal.
5. The field effect tube type gas sensor according to claim 1, wherein the thickness of each of the metal thin film layers is 0.5 to 1nm.
6. The method for manufacturing a field effect tube type gas sensor according to any one of claims 1 to 5, comprising the steps of:
s1, adopting a doped semiconductor substrate, wherein the surface of the substrate is provided with an insulating layer, removing part of the insulating layer, and manufacturing a back gate electrode on the substrate with the insulating layer removed, so that the bottom of the back gate electrode is contacted with the doped semiconductor substrate through a removed insulating layer region;
s2, transferring or depositing the graphene film on the surface of the insulating layer, and separating the graphene film from the back gate electrode;
s3, carrying out graphical treatment on the graphene film, and removing redundant parts of the graphene film;
s4, respectively preparing a source electrode and a drain electrode at two ends of the surface of the graphene film obtained in the step S3;
and S5, sequentially depositing metal on the surface of the graphene film between the source electrode and the drain electrode, and cleaning the surface to obtain the field effect tube type gas sensor.
7. The method of claim 6, wherein the semiconductor is silicon, silicon carbide, sapphire, or silicon nitride.
8. The method of claim 6, wherein the insulating layer is SiO 2 、Al 2 O 3 Or HaO 2 。
9. Use of a field effect tube type gas sensor according to any one of claims 1 to 5 in gas detection.
10. Use according to claim 9, wherein the gas is ammonia, hydrogen sulphide or carbon monoxide.
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