CN114646419B - Gas pressure sensor, preparation method thereof and gas pressure detection method - Google Patents
Gas pressure sensor, preparation method thereof and gas pressure detection method Download PDFInfo
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- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L9/00—Measuring steady of quasi-steady pressure of fluid or fluent solid material by electric or magnetic pressure-sensitive elements; Transmitting or indicating the displacement of mechanical pressure-sensitive elements, used to measure the steady or quasi-steady pressure of a fluid or fluent solid material, by electric or magnetic means
- G01L9/02—Measuring steady of quasi-steady pressure of fluid or fluent solid material by electric or magnetic pressure-sensitive elements; Transmitting or indicating the displacement of mechanical pressure-sensitive elements, used to measure the steady or quasi-steady pressure of a fluid or fluent solid material, by electric or magnetic means by making use of variations in ohmic resistance, e.g. of potentiometers, electric circuits therefor, e.g. bridges, amplifiers or signal conditioning
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Abstract
The invention discloses a gas pressure sensor, a preparation method thereof and a gas pressure detection method; the gas pressure sensor comprises a substrate, an insulating layer, a two-dimensional material layer and two electrodes, wherein the insulating layer is laminated on the substrate, a groove is formed in the insulating layer, the two electrodes are arranged on one side, away from the substrate, of the insulating layer and are respectively located on two sides of the groove, the two-dimensional material layer is suspended above the groove, two ends of the two-dimensional material layer are respectively connected with the two electrodes, a first bias voltage is configured on the two-dimensional material layer through the two electrodes, and a second bias voltage is configured between the substrate and any electrode. When the device is exposed to a gas environment, the upper and lower surfaces of the suspended two-dimensional material adsorb gas molecules, so that the conductivity of the device is influenced; the conductivity of the device under different air pressures can be obtained by configuring two bias voltages, so that the ambient air pressure is reflected. The gas pressure sensor is of an on-chip integrated structure, and has the characteristics of microminiature, low power consumption, wide range and simple structure.
Description
Technical Field
The invention belongs to the technical field of sensors, and particularly relates to a gas pressure sensor, a preparation method thereof and a gas pressure detection method.
Background
The gas pressure sensor is a core element for realizing gas pressure measurement and is widely applied to the aspects of electronic information equipment, aerospace equipment, surface science analysis equipment and the like. Miniaturization, high precision, ultra-low power consumption, high reliability and wide range are development trends of air pressure measuring devices and equipment; in particular, in the special application fields of deep space exploration, near space exploration and the like, and in vacuum packaged MEMS devices such as gyroscopes, micro accelerometers and the like, the restriction of volume, power consumption and reliability on the air pressure measuring device is more obvious. The gas pressure sensor developed by the micro-nano processing technology has the advantages of small volume, light weight and low power consumption, not only can miniaturize the gas pressure sensor, but also can realize on-chip integration and interconnection of the sensor and a signal processing, control circuit and communication circuit, and is a research hot spot in the current air pressure measurement field and a difficulty in upgrading an air pressure measuring instrument. Currently, three types of gas pressure sensors, thermal resistive, capacitive, and ionization, are limited in their miniaturization and integration. For example, miniaturization of the thermal resistance type air pressure sensor and the capacitance film air pressure sensor, the effective area of the sensing function unit (hot wire and capacitance film, respectively) thereof will be reduced, resulting in a drastic decrease in measurement accuracy and measurement range. Reducing the volume of the ionization type barometric sensor reduces the collision probability of electrons and gas, and therefore barometric detection cannot be achieved. Therefore, the exploration of new detection principles and methods suitable for miniaturized air pressure sensors is of great importance in facilitating the development and application of miniaturized air pressure sensors.
In the prior art, the gas adsorption is widely applied to a gas sensing device for adjusting the conductive property of a semiconductor material, and in gas sensing, the device is required to distinguish specific gases with low concentration and different responsivity to different gases is mainly measured. In air pressure sensing, particularly air pressure sensing for vacuum measurement, the important focus is on the measurement range, the device is required to have response capability in air pressure change of crossing orders of magnitude, and new requirements are put on sensing materials and device structures; the sensing material is required to have obvious resolving power to different air pressures, and meanwhile, the adsorption and desorption of air can be rapidly completed in the air pressure change process, and the influence of Joule heat generated by the work of a device on the adsorption and desorption is required to be avoided as much as possible, so that the measurement accuracy is influenced.
Disclosure of Invention
The invention aims to overcome at least one defect in the prior art, and provides a gas pressure sensor, a preparation method thereof and a gas pressure detection method.
In order to solve the technical problems, the invention adopts the following technical scheme:
the utility model provides a gas pressure sensor, including substrate, insulating layer, two-dimensional material layer and two electrodes, insulating layer stacks up and locates on the substrate, the preparation has the slot on the insulating layer, two electrodes set up in insulating layer one side that deviates from the substrate and lie in the both sides of slot respectively, two-dimensional material layer unsettled in slot top and both ends link to each other with two electrodes respectively, two-dimensional material layer has first bias voltage through two electrodes configuration, it has the perpendicular electric field of second bias voltage in order to produce by the directional two-dimensional material layer of substrate to dispose between any one of substrate and two electrodes.
In this scheme, when the sensor is in the gas environment, gas molecules adsorb on the surface of two-dimensional material layer, and wherein polar molecules such as water molecules, oxygen, nitrogen dioxide molecules will take place charge transfer with two-dimensional material layer. When water molecules and oxygen molecules are adsorbed on the surface of the two-dimensional material layer, free electrons in the two-dimensional material layer are transferred to gas molecules, so that the number of free electrons in the two-dimensional material layer is reduced, the resistance value is increased, and the conductivity is reduced. And, gas molecules adsorb on the surface of the two-dimensional material layer, become scattering centers, reduce the mobility of free electrons, and further reduce the conductivity of the two-dimensional material. When the ambient air pressure value is increased, the number of gas molecules is increased, and the gas molecules adsorbed on the surface are increased, so that the effect is more obvious along with the increase of the air pressure. Therefore, the resistance value or the conductivity of the two-dimensional material can be obtained by applying the first bias voltage to the two ends of the two-dimensional material layer and measuring the loop current value, so that the air pressure value of the environment can be judged. In addition, bias voltage is applied to the substrate of the device to generate a vertical electric field, and the vertical electric field promotes charge transfer between the two-dimensional material layer and adsorbed gas molecules, so that the conductivity of the two-dimensional material is more obviously influenced by the adsorbed gas molecules, and the sensitivity of the device to gas pressure changes is increased.
Preferably, the two-dimensional material layer is made of one or more of transition metal chalcogenide, transition metal carbon/nitride, graphene oxide and black phosphorus.
Preferably, the thickness of the two-dimensional material layer is about 2-7 nm, and the area of the upper surface is 50-2000 μm 2 。
Preferably, the length of the groove is 0.5-1.5 mm, the width is 2-6 μm, and the depth is 300-700 nm.
Preferably, the substrate is a metal, silicon or insulating substrate with a conductive film coated on the surface.
Preferably, the thickness of the insulating layer is 300nm to 700nm, and the insulating layer is made of one or more of silicon dioxide, aluminum oxide, hafnium oxide, silicon nitride, titanium oxide or zirconium oxide.
The scheme also provides a preparation method of the gas pressure sensor, which comprises the following steps:
s1, preparing an insulating layer on a substrate, and spin-coating photoresist on the upper surface of the insulating layer by using a photoresist homogenizing machine;
s2, exposing the photoresist by using a photoetching system, and then developing to obtain a groove pattern;
s3, etching and removing the insulating layer which is not protected by the photoresist by using the photoresist which is not exposed as a mask to obtain a groove;
s4, transferring the two-dimensional material layer to the upper part of the groove by adopting a transfer method, and spin-coating photoresist on the surfaces of the insulating layer and the two-dimensional material layer by utilizing a photoresist homogenizing machine; exposing the photoresist by using a photoetching system, and then developing in a developing solution to obtain an electrode pattern;
s5, plating a layer of metal on the surface of the sample after the step S4, placing the sample in an acetone solution, and removing photoresist in an unexposed area and metal above the photoresist to obtain a sample with an electrode;
s6, placing the sample in a nitrogen atmosphere for thermal annealing to obtain the gas pressure sensor.
The scheme also provides a gas pressure detection method using the gas pressure sensor, which comprises the following steps:
s101, placing a gas pressure sensor in a first pressure state of the same type of gas as the environment to be detected;
s201, applying a first bias voltage to electrodes at two ends of a two-dimensional material layer to enable loop current to be formed inside the two-dimensional material layer; applying a second bias voltage between the substrate and either of the two electrodes simultaneously; maintaining the first bias voltage and the second bias voltage for a first set period t, recording the calibration current value of the loop current of the two-dimensional material layer in the first set period t, and calculating to obtain the calibration current average value in the first set period;
s301, changing the value of the first pressure state for a plurality of times, sequentially repeating the process of the step S201, measuring a plurality of calibration current average values of loop currents of the two-dimensional material layer under different pressures within the same first set period t, and obtaining a curve of the calibration current average value along with the gas pressure according to the plurality of calibration current average values;
s401, placing a gas pressure sensor in an environment to be tested, applying a first bias voltage on electrodes at two ends of a two-dimensional material layer, applying a second bias voltage between a substrate and any one of the two electrodes, and maintaining for a first set period t to obtain an actual current average value of loop current of the two-dimensional material layer, and comparing the actual current average value with a curve of calibrating current average value along with gas pressure in the step S301 to obtain a gas pressure value of the environment to be tested.
Preferably, the gas in the environment to be measured is one of air, oxygen, nitric oxide, nitrogen dioxide, carbon monoxide, carbon dioxide or ammonia and hydrogen.
Preferably, the first bias voltage is 1V, the second bias voltage is 8V, and the first set period is 3min.
Compared with the prior art, the beneficial effects are that:
the gas pressure sensor adopts a two-dimensional material layer as a gas pressure sensing element, and has the characteristics of high specific area and small characteristic size; the working principle is simple, all the components are integrated on a single chip, and the device is of an integrated structure and has the characteristics of wide measuring range, low power consumption and high sensitivity.
Drawings
FIG. 1 is a schematic view showing the overall structure of a gas pressure sensor according to embodiment 1 of the present invention;
FIG. 2 is an optical micro-topography of a gas pressure sensor of example 1 of the present invention;
FIG. 3 is a response curve of the gas pressure sensor according to embodiment 8 of the present invention, wherein the average value of the current varies with the gas pressure when the first bias voltage is 1V and the second bias voltage is 8V;
FIG. 4 is an optical micro-topography of a comparative example 1 gas pressure sensor;
fig. 5 is a response characteristic curve of the gas pressure sensor of comparative example 1 in which the average value of current varies with the gas pressure when the first bias voltage is 1V and the second bias voltage is 8V.
Detailed Description
The drawings are for illustrative purposes only and are not to be construed as limiting the invention; for the purpose of better illustrating the embodiments, certain elements of the drawings may be omitted, enlarged or reduced and do not represent the actual product dimensions; it will be appreciated by those skilled in the art that certain well-known structures in the drawings and descriptions thereof may be omitted. The positional relationship described in the drawings are for illustrative purposes only and are not to be construed as limiting the invention.
The same or similar reference numbers in the drawings of embodiments of the invention correspond to the same or similar components; in the description of the present invention, it should be understood that, if there are orientations or positional relationships indicated by terms "upper", "lower", "left", "right", "long", "short", etc., based on the orientations or positional relationships shown in the drawings, this is merely for convenience in describing the present invention and simplifying the description, and is not an indication or suggestion that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, so that the terms describing the positional relationships in the drawings are merely for exemplary illustration and are not to be construed as limitations of the present patent, and that it is possible for those of ordinary skill in the art to understand the specific meaning of the terms described above according to specific circumstances.
The technical scheme of the invention is further specifically described by the following specific embodiments with reference to the accompanying drawings:
example 1:
referring to fig. 1 to 2, a first embodiment of a gas pressure sensor includes a substrate 1, an insulating layer 2, a two-dimensional material layer 3 and two electrodes 4, wherein the insulating layer 2 is stacked on the substrate 1, a trench is formed on the insulating layer 2, the two electrodes 4 are disposed on one side of the insulating layer 2 away from the substrate 1 and are respectively located at two sides of the trench, the two-dimensional material layer 3 is suspended above the trench and is respectively connected with the two electrodes 4 at two ends, the two-dimensional material layer 3 is configured with a first bias voltage through the two electrodes 4, and a second bias voltage is configured between the substrate 1 and any one of the two electrodes 4 to generate a vertical electric field directed to the two-dimensional material layer 3 by the substrate 1.
The grooves in this embodiment can increase the contact area between the two-dimensional material layer 3 and the ambient gas, thereby increasing the number of gas molecules adsorbed by the two-dimensional material layer, and making the response range of the two-dimensional material layer to the change of the air pressure larger, the sensitivity and the measurement range larger.
In this embodiment, the vertical electric field can promote charge transfer between the two-dimensional material layer 3 and the gas molecules, so that the conductivity of the device is more obviously affected by the adsorbed gas molecules, and the sensitivity to air pressure changes is increased.
The two-dimensional material layer 3 in this embodiment is formed by sequentially laminating more than five layers of two-dimensional materials, the overall thickness is 2nm, and the area of the upper surface is 50 μm 2 Can be made of molybdenum disulfide. Of course, this is only a reference embodiment, and should not be construed as limiting the present embodiment, in the specific implementation process, the number of layers, thickness and area of the two-dimensional material layer 3 may be increased or decreased according to actual situations, and other types of transition metal chalcogenides may also be selected as the material.
In this embodiment, the length of the trench is 0.5mm, the width is 2 μm, and the depth is 300nm, so that the two-dimensional material layer 3 can span over the trench along the width direction of the trench, and two ends of the two-dimensional material layer 3 are connected with the two electrodes 4, so that the upper and lower surfaces of the two-dimensional material layer 3 can contact gas molecules, the absorption capacity of the two-dimensional material layer 3 to the gas molecules is improved, and the measurement range and sensitivity of the gas pressure sensor are further improved. It should be noted that the dimensional parameters of the trenches in this embodiment are only reference embodiments, and should not be construed as limiting the present embodiment, and the dimensional parameters of the two-dimensional material layer 3 may be changed correspondingly during implementation.
The substrate 1 in this embodiment has a doping concentration of 10 19 /cm 3 Of course, this is only a preferred embodiment, and other types of silicon or metal, insulating substrates coated with a conductive film on the surface thereof can be used in the implementation to realize the conductive and supporting functions of the substrate 1The bias voltage is applied directly to the substrate 1, generating an electric field directed from the substrate 1 to the two-dimensional material layer 3.
In a specific embodiment, the insulating layer 2 is made of silicon dioxide, with a thickness of 300nm, by which the substrate 1 is prevented from shorting with the two-dimensional material layer 3.
In a specific embodiment, the material of the electrode 4 is a Ti/Au stack.
The gas pressure sensor in this embodiment is suitable for a gas environment with polar molecules such as air, oxygen, nitric oxide, nitrogen dioxide, carbon monoxide, carbon dioxide or ammonia, hydrogen, and the like.
The response range of the gas pressure sensor of the embodiment to the change of the gas pressure is 6×10 -4 ～10 5 Pa, the power consumption is less than 5nW, and the sensitivity is about 5.5 omega/Pa.
The working principle of the embodiment is as follows:
when the sensor is in a gaseous environment, gas molecules are adsorbed on the surface of the two-dimensional material layer 3, wherein polar molecules such as water molecules, oxygen, nitrogen dioxide molecules will undergo charge transfer with the two-dimensional material layer 3. When water molecules and oxygen molecules are adsorbed on the surface of the two-dimensional material layer 3, free electrons in the two-dimensional material layer 3 are transferred to gas molecules, so that the number of free electrons in the two-dimensional material layer 3 is reduced, the resistance value is increased, and the conductivity is reduced. In addition, after the gas molecules are adsorbed on the surface of the two-dimensional material layer 3, the gas molecules become scattering centers, so that the mobility of free electrons is reduced, and the conductivity of the two-dimensional material is further reduced. When the ambient air pressure value is increased, the number of gas molecules is increased, and the gas molecules adsorbed on the surface are increased, so that the effect is more obvious along with the increase of the air pressure, in addition, the two-dimensional material layer 3 is suspended above the groove, the contact area between the two-dimensional material layer 3 and the gas molecules is larger, and the more the gas molecules can be adsorbed. Therefore, the resistance value or the conductivity of the two-dimensional material can be obtained by applying the first bias voltage to both ends of the two-dimensional material layer 3 and measuring the loop current value, thereby judging the air pressure value of the environment. In addition, a bias voltage is applied to the substrate 1 of the device, so that a vertical electric field is generated, the vertical electric field promotes charge transfer between the two-dimensional material layer 3 and adsorbed gas molecules, the conductivity of the two-dimensional material is more obviously influenced by the adsorbed gas molecules, and the sensitivity of the device to gas pressure changes is increased.
Example 2:
the difference between this embodiment and embodiment 1 is that the thickness of the two-dimensional material layer 3 in this embodiment is 5nm, and the area of the upper surface of the two-dimensional material layer 3 is 150 μm 2 The method comprises the steps of carrying out a first treatment on the surface of the The length of the groove is 1nm, the width is 4 mu m, and the depth is 500nm; the thickness of the insulating layer 2 was 500nm.
Example 3:
the difference between this embodiment and embodiment 1 or embodiment 2 is only that the thickness of the two-dimensional material layer 3 in this embodiment is 7nm, and the area of the upper surface of the two-dimensional material layer 3 is 200 μm2; the length of the groove is 1.5nm, the width is 6 μm, and the depth is 500nm; the thickness of the insulating layer 2 was 700nm.
Example 4:
the present embodiment differs from any one of embodiments 1 to 3 only in that the material of the two-dimensional material layer 3 is replaced with one of transition metal carbo/nitride, graphene oxide, or black phosphorus in the present embodiment.
Example 5:
the present embodiment differs from any one of embodiment 1 to embodiment 4 only in that the material of the insulating layer 2 is replaced with one or more of silicon nitride, aluminum oxide, hafnium oxide, titanium oxide, or zirconium oxide in the present embodiment.
Example 6:
the present embodiment differs from any one of embodiment 1 to embodiment 5 only in that the material of the substrate 1 is replaced with a metal or an insulating substrate having a surface plated with a conductive film in the present embodiment.
Example 7:
the embodiment is a method for manufacturing a gas pressure sensor, which comprises the following steps:
s1, silicon dioxide with the thickness of about 500nm is deposited on a silicon substrate 1 by adopting a plasma enhanced chemical vapor deposition method to serve as an insulating layer 2. A photoresist (ARP-6200) having a thickness of about 1 μm was spin-coated on the silica surface using a spin coater.
S2, exposing the photoresist by using a photoetching system. And then a groove pattern is obtained through development, the development process adopts xylene for development, and isopropanol for fixation is adopted.
S3, etching the silicon dioxide layer which is not protected by the photoresist by using the photoresist which is not exposed as a mask by using an Inductively Coupled Plasma (ICP) system to obtain a groove, wherein the width of the groove is 4 mu m, and the depth is 500nm.
S4, transferring the molybdenum disulfide to the upper part of the groove by adopting a dry transfer method, wherein the number of layers of the two-dimensional material is more than 5, and the thickness is more than 3nm. Spin-coating photoresist (RZJ-325) with the thickness of about 500nm on the surface of silicon dioxide and molybdenum disulfide by using a spin coater; the photoresist was exposed using a photolithography system and then developed in a sodium hydroxide solution to obtain an electrode pattern.
S5, adopting a thermal evaporation device to plate the Ti/Au metal electrode 4, wherein the thickness of Ti is about 10nm, and the thickness of Au is about 100nm. The sample was placed in an acetone solution and the photoresist and the metal above the unexposed areas were removed to give a sample with electrode 4.
S6, placing the sample in a nitrogen atmosphere for thermal annealing, wherein the annealing temperature is 350 ℃, and maintaining for 2 hours.
Example 8:
as shown in fig. 3, a gas pressure detection method using the gas pressure sensor of any one of embodiments 1 to 6 includes the steps of:
s101, placing a gas pressure sensor in a cavity filled with the same type of gas as the environment to be tested, and pumping the gas pressure in the cavity to 10 -4 Pa, the first pressure state; of course, the initial air pressure can be set according to the actual situation, and the reference embodiment is only used herein and is not to be construed as limiting the scheme;
s201, applying a first bias voltage to the electrodes 4 at two ends of the two-dimensional material layer 3 to enable loop current to be formed inside the two-dimensional material layer 3; simultaneously, a second bias voltage is applied between the substrate 1 and any one of the two electrodes 4, so that a vertical electric field which is directed to the two-dimensional material layer 3 by the substrate 1 is generated, and charge transfer between the two-dimensional material layer 3 and gas molecules adsorbed on the two-dimensional material layer is promoted; maintaining the first bias voltage and the second bias voltage for a first set period t, recording the calibration current value of the loop current of the two-dimensional material layer 3 in the first set period t, and calculating to obtain the calibration current average value in the first set period t;
s301, inflating the cavity for multiple times to enable the air pressure in the cavity to slowly rise, sequentially repeating the process of the step S201, measuring multiple calibration current average values of loop current of the two-dimensional material layer 3 under different pressures in the same first set period t, and obtaining a variation curve of the calibration current average value along with the air pressure according to the multiple calibration current average values (see FIG. 3); preferably, three measurement points are selected to measure within one air pressure order; therefore, the gas pressure sensor can be calibrated before detection, so that the gas pressure sensor is suitable for various gas types, and the detection accuracy is higher;
s401, placing a gas pressure sensor in an environment to be detected, applying a first bias voltage on electrodes 4 at two ends of a two-dimensional material layer 3 to enable loop current to be generated in the two-dimensional material layer 3, applying a second bias voltage between a substrate 1 and any one of the two electrodes 4 to generate a vertical electric field which is directed to the two-dimensional material layer 3 by the substrate 1, maintaining the first bias voltage and the second bias voltage for a first set period t to obtain an actual current average value of the loop current of the two-dimensional material layer 3, and comparing the actual current average value with a curve of the current average value calibrated in step S301 along with the gas pressure change to obtain a gas pressure value of the environment to be detected; the vertical electric field can promote charge transfer between the two-dimensional material layer 3 and gas molecules, so that the conductivity of the two-dimensional material layer 3 is more obviously influenced by adsorbed gas molecules, the sensitivity of the whole device to air pressure change is higher, and the sensitivity and the accuracy of detection are improved.
The gas in the environment to be measured in the embodiment is one of air, oxygen, nitric oxide, nitrogen dioxide, carbon monoxide, carbon dioxide or ammonia and hydrogen.
In this embodiment, the first bias voltage is 1V, the second bias voltage is 8V, and the first set period is 3min, however, these values are only selected as reference embodiments, and the method is not to be understood as limiting the scheme, and in the specific implementation process, the voltage value and the maintaining time can be changed according to actual situations.
Comparative example 1:
the comparative example is a comparative example of any one of examples 1 to 6, except that the insulating layer 2 in the comparative example was not formed with grooves (see fig. 4), i.e., the two-dimensional material layer 3 was of a non-suspended structure, and only the upper surface of the two-dimensional material was in contact with ambient gas, and as a result, it was revealed that the adsorption area of the device, i.e., the number of adsorbed gas molecules, was reduced, the response range to changes in air pressure was reduced, the sensitivity was lowered (see fig. 5), and the measurement range was 3×10 -3 ～10 5 Pa, the sensitivity is about 1.6. OMEGA/Pa.
The present invention is described with reference to flowchart illustrations or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the application, it being understood that each flowchart illustration or block in the flowchart illustrations or block diagrams, and combinations of flowcharts or blocks in the flowchart illustrations or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
While embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and not to be construed as limiting the invention, and that variations, modifications, alternatives and variations may be made to the above embodiments by one of ordinary skill in the art within the scope of the invention.
It is to be understood that the above examples of the present invention are provided by way of illustration only and not by way of limitation of the embodiments of the present invention. Other variations or modifications of the above teachings will be apparent to those of ordinary skill in the art. It is not necessary here nor is it exhaustive of all embodiments. Any modification, equivalent replacement, improvement, etc. which come within the spirit and principles of the invention are desired to be protected by the following claims.
Claims (10)
1. The utility model provides a gas pressure sensor, is applicable to the gaseous environment that has polar molecule, its characterized in that includes substrate (1), insulating layer (2), two-dimensional material layer (3) and two electrode (4), insulating layer (2) fold and locate on substrate (1), the preparation has the slot on insulating layer (2), two electrode (4) set up in one side that insulating layer (2) deviate from substrate (1) and lie in the both sides of slot respectively, two-dimensional material layer (3) unsettled in slot top and both ends link to each other with two electrode (4) respectively, two-dimensional material layer (3) are through two electrode (4) configuration have first offset voltage, be configured with second offset voltage between any one of substrate (1) and two electrode (4) in order to produce the perpendicular electric field that is directional by substrate (1) two-dimensional material layer (3), the perpendicular electric field will promote charge transfer between two-dimensional material layer (3) and the gaseous molecule of absorption for the electric conductivity of two-dimensional material layer (3) receives more obvious influence of the gaseous molecule.
2. A gas pressure sensor according to claim 1, characterized in that the two-dimensional material layer (3) is made of one or more of transition metal chalcogenide, transition metal carbo/nitride, graphene oxide, black phosphorus.
3. A gas pressure sensor according to claim 2, characterized in that the thickness of the two-dimensional material layer (3) is about 2-7 nm, the area of the upper surface is 50-2000 μm 2 。
4. A gas pressure sensor according to any one of claims 1 to 3, wherein the grooves have a length of 0.5 to 1.5mm, a width of 2 μm to 6 μm and a depth of 300nm to 700nm.
5. A gas pressure sensor according to claim 4, characterized in that the substrate (1) is a metal, silicon or an insulating substrate with a conductive film coated on the surface.
6. A gas pressure sensor according to claim 5, characterized in that the thickness of the insulating layer (2) is 300-700 nm, the insulating layer (2) being made of one or more of silicon dioxide, aluminum oxide, hafnium oxide, silicon nitride, titanium oxide or zirconium oxide.
7. A method of manufacturing a gas pressure sensor according to any one of claims 1 to 6, comprising the steps of:
s1, preparing an insulating layer (2) on a substrate (1), and spin-coating photoresist on the upper surface of the insulating layer (2) by using a photoresist homogenizer;
s2, exposing the photoresist by using a photoetching system, and then developing to obtain a groove pattern;
s3, etching and removing the insulating layer (2) which is not protected by the photoresist by using the photoresist which is not exposed as a mask to obtain a groove;
s4, transferring the two-dimensional material layer (3) to the upper part of the groove by adopting a transfer method, and spin-coating photoresist on the surfaces of the insulating layer (2) and the two-dimensional material layer (3) by utilizing a photoresist homogenizing machine; exposing the photoresist by using a photoetching system, and then developing in a developing solution to obtain an electrode (4) pattern;
s5, plating a layer of metal on the surface of the sample after the step S4, placing the sample in an acetone solution, and removing photoresist in an unexposed area and metal above the photoresist to obtain a sample with an electrode (4);
s6, placing the sample in a nitrogen atmosphere for thermal annealing to obtain the gas pressure sensor.
8. A gas pressure detection method using the gas pressure sensor according to any one of claims 1 to 6, characterized by comprising the steps of:
s101, placing a gas pressure sensor in a first pressure state of the same type of gas as the environment to be detected;
s201, applying a first bias voltage to electrodes (4) at two ends of the two-dimensional material layer (3) to enable loop current to be formed inside the two-dimensional material layer (3); simultaneously applying a second bias voltage between the substrate (1) and either of the two electrodes (4); maintaining the first bias voltage and the second bias voltage for a first set period t, recording the calibration current value of the loop current of the two-dimensional material layer (3) in the first set period t, and calculating to obtain the calibration current average value in the first set period t;
s301, changing the value of the first pressure state for a plurality of times, sequentially repeating the process of the step S201, measuring a plurality of calibration current average values of loop current of the two-dimensional material layer (3) under different pressures within the same first set period t, and obtaining a variation curve of the calibration current average value along with the gas pressure according to the plurality of calibration current average values;
s401, placing a gas pressure sensor in an environment to be detected, applying a first bias voltage on electrodes (4) at two ends of a two-dimensional material layer (3), applying a second bias voltage between a substrate (1) and any one of the two electrodes (4), maintaining the first bias voltage and the second bias voltage for a first set period t, obtaining an actual current average value of loop current of the two-dimensional material layer (3), and comparing the actual current average value with a curve of the calibration current average value along with the gas pressure in the step S301 to obtain the gas pressure value of the environment to be detected.
9. The method according to claim 8, wherein the gas in the environment to be measured is air, oxygen, nitric oxide, nitrogen dioxide, carbon monoxide, carbon dioxide or ammonia, hydrogen.
10. The gas pressure detection method according to claim 9, wherein the first bias voltage is 1V, the second bias voltage is 8V, and the first set period is 3min.
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