CN113109402B - Capacitive hydrogen sensor core, preparation method thereof and capacitive hydrogen sensor - Google Patents
Capacitive hydrogen sensor core, preparation method thereof and capacitive hydrogen sensor Download PDFInfo
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- 238000000034 method Methods 0.000 claims description 58
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- UQZIWOQVLUASCR-UHFFFAOYSA-N alumane;titanium Chemical compound [AlH3].[Ti] UQZIWOQVLUASCR-UHFFFAOYSA-N 0.000 claims description 7
- 229910052782 aluminium Inorganic materials 0.000 claims description 7
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- MSNOMDLPLDYDME-UHFFFAOYSA-N gold nickel Chemical compound [Ni].[Au] MSNOMDLPLDYDME-UHFFFAOYSA-N 0.000 claims description 7
- 238000010438 heat treatment Methods 0.000 claims description 7
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 6
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 claims description 6
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- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 32
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- 239000003990 capacitor Substances 0.000 description 9
- 230000008859 change Effects 0.000 description 9
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- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 6
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- 230000003647 oxidation Effects 0.000 description 5
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- 238000003745 diagnosis Methods 0.000 description 2
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- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
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- G01N27/22—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating capacitance
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- G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
- G01N27/22—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating capacitance
- G01N27/226—Construction of measuring vessels; Electrodes therefor
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
- G01N27/22—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating capacitance
- G01N27/227—Sensors changing capacitance upon adsorption or absorption of fluid components, e.g. electrolyte-insulator-semiconductor sensors, MOS capacitors
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Abstract
The invention provides a capacitive hydrogen sensor core, a preparation method thereof and a capacitive hydrogen sensor, wherein the capacitive hydrogen sensor core comprises: the substrate, the dielectric sheet and the second electrode are sequentially arranged from bottom to top; wherein the substrate is arranged as a conductive material layer; the second electrode is arranged as a hydrogen sensitive layer; the dielectric sheet is a group III nitride layer, and the end surface of the dielectric sheet facing away from the substrate is oxidized into a group III oxide layer. The second electrode is brought into contact with the group iii oxide layer by oxidizing the end face of the group iii nitride dielectric sheet facing away from the substrate into the group iii oxide layer. When the capacitive hydrogen sensor is exposed to hydrogen, hydrogen atoms are diffused and adsorbed at the contact interface of the III-group oxide layer and the second electrode, the III-group oxide layer directly interacts with the hydrogen atoms, the adsorption and desorption of the hydrogen atoms are promoted to reach an equilibrium state, and finally, the capacitive hydrogen sensor core has the advantages of low detection lower limit, high response speed, safety and reliability.
Description
Technical Field
The invention relates to the technical field of hydrogen concentration detection, in particular to a capacitive hydrogen sensor core, a preparation method thereof and a capacitive hydrogen sensor.
Background
Hydrogen element on earth is very abundant, and hydrogen can be prepared through water electrolysis, photocatalysis, chemical process and the like. The hydrogen energy source is wide, green and renewable, and is expected to become the most important energy form in the near future to be widely applied to the fields of hydrogen fuel cell automobiles, aerospace, chemical industry, electrons and the like. However, hydrogen is colorless, odorless, transparent, and not easily found even if leaked during production, transportation, and use. Hydrogen is a flammable and explosive gas, which is prone to combustion or explosion accidents when the volume concentration in the air is 4-75%. Therefore, a sensor capable of rapidly detecting the concentration of hydrogen is required to perform early warning and prediction on hydrogen leakage, and hydrogen is used as an important marker of digestive tract diseases, and the hydrogen sensor is also an extremely important core component in diagnosis of expiratory diseases in medical treatment. These applications require hydrogen sensors with low lower detection limit LOD and rapid detection capability to discover hydrogen leakage and take relevant protective measures as early as possible.
Currently, hydrogen sensors mainly include optical fiber sensing type, metal semiconductor oxide resistor type, electrochemical type, catalytic combustion type, field effect transistor type, capacitance type and the like. The optical fiber sensing detector has good safety, but mainly tests high-concentration hydrogen; the metal-semiconductor oxide resistance sensor has simple structure, low cost and long response time, and can test low-concentration hydrogen; the catalytic combustion type sensor is applied to partial hydrogen fuel cell automobiles at present, has ultra-fast response speed, high stability and wide detection range, but can only detect hydrogen with the concentration of more than 1000ppm generally, and cannot detect hydrogen with low concentration; the capacitive sensor has the excellent characteristics of small baseline drift, insensitivity to environmental change and the like, does not generate electric sparks during working, can not ignite and detonate high-concentration hydrogen even if the high-concentration hydrogen leaks, and has high safety and reliability. Currently available sensors either have high detection limits, slow response speeds (greater than 3 s), or are not safe. Therefore, how to provide a hydrogen sensor with low detection lower limit, high response speed, safety and reliability is a technical problem to be solved.
Disclosure of Invention
The invention aims to solve the technical problems that the hydrogen sensor in the prior art cannot achieve low detection lower limit, high response speed and safety and reliability.
The technical scheme adopted for solving the technical problems is as follows: a capacitive hydrogen sensor core, comprising:
the substrate, the dielectric sheet and the second electrode are sequentially arranged from bottom to top;
wherein the substrate is provided as a layer of conductive material; the second electrode is arranged as a hydrogen sensitive layer; the dielectric sheet is a III-nitride layer, and the end face of the dielectric sheet, which is away from the substrate, is oxidized into a III-oxide layer.
In the capacitive hydrogen sensor core, the second electrode is arranged as the hydrogen sensitive layer, and when the second electrode contacts with hydrogen, the second electrode adsorbs and decomposes the hydrogen into hydrogen atoms; meanwhile, the substrate is set to be a conductive material layer, and then an electrode is formed by the substrate, meanwhile, the dielectric sheet is set to be a III-group nitride layer, III-group nitride is used as an isolation layer of a capacitor, the second electrode, the conductive material layer and the dielectric sheet form a capacitive hydrogen sensor core, hydrogen atoms can be diffused and adsorbed at the interface of the III-group nitride layer and the second electrode, and a dipole layer is formed, so that capacitance change is caused, and the effects of safety, reliability and low detection lower limit are further realized; simultaneously, directly oxidizing the area on the surface of the III-group nitride, and forming a III-group oxide layer on the surface of the III-group nitride; the second electrode is contacted with the III-group oxide layer, hydrogen atoms are also enabled to diffuse and be adsorbed at the interface of the III-group oxide layer and the second electrode, meanwhile, the III-group oxide layer directly interacts with the hydrogen atoms, the adsorption and desorption of the hydrogen atoms can reach an equilibrium state very fast, the characteristic of ultra-fast response speed is further achieved, and finally the capacitive hydrogen sensor core body is enabled to simultaneously have the advantages of low detection lower limit, fast response speed, safety and reliability.
Further, the substrate is set as monocrystalline silicon piece or silicon carbide piece, the thickness is 0.001-3 mm;
the capacitive hydrogen sensor core further comprises a first electrode;
the first electrode is arranged on the end face of the matrix, which is away from the dielectric sheet; or, the first electrode is arranged on the surface of the dielectric sheet, which is away from the substrate, and the first electrode and the second electrode are arranged at intervals.
According to the capacitive hydrogen sensor core, the substrate can have the conductivity; meanwhile, a first electrode can be additionally arranged, the setting position of the first electrode is controlled, and therefore the capacitive hydrogen sensor core is guaranteed to have the advantages of being low in detection lower limit, high in response speed and safe and reliable in performance, meanwhile, the first electrode and the second electrode are arranged on the surface, deviating from the substrate, of the dielectric sheet, the response speed of the capacitive hydrogen sensor core is further improved, the thickness of the capacitive hydrogen sensor core is reduced, and miniaturization of the capacitive hydrogen sensor core is facilitated.
Further, the III-nitride layer comprises a GaN layer and Al x Ga 1-x N layer or In x Ga 1-x An N layer; the III-oxide layer comprises Ga 2 O 3 Layer, al x Ga 2-x O 3 Layer or In x Ga 2-x O 3 A layer, wherein X is 0-0.5;
the thickness of the dielectric sheet is 0.02-10 mu m, and the thickness of the III-group oxide layer is 2-30 nm;
the first electrode is an aluminum electrode, a gold electrode, a titanium aluminum electrode, a nickel-gold electrode, a chromium-gold electrode, a copper-gold electrode, a titanium-gold electrode, a platinum electrode or a palladium electrode, and the thickness of the first electrode is 1-500 nm;
the second electrode is a platinum electrode or a palladium electrode, and the thickness of the second electrode is 1-1000 nm.
In the capacitive hydrogen sensor core, the material of the second electrode is controlled, so that the second electrode is set to be a hydrogen sensitive layer; the first electrode and the second electrode can be arranged as hydrogen sensitive layers, so that the sensitivity of the capacitive hydrogen sensor core can be further improved.
The invention solves the technical problem by adopting another technical scheme as follows: a method of making a capacitive hydrogen sensor core, comprising:
generating a dielectric sheet made of III-nitride material on a conductive substrate;
pretreating the dielectric sheet, and oxidizing the pretreated dielectric sheet at one end, which is far away from the matrix, to obtain a III-group oxide layer;
And generating a second electrode on the III group oxide layer by a magnetron sputtering method or an electron beam evaporation method.
The preparation method of the capacitive hydrogen sensor core body comprises the steps that the dielectric sheet is set to be a III-group nitride layer, III-group nitride is used as an isolation layer of a capacitor, and the second electrode, the conductive material layer and the dielectric sheet form the capacitive hydrogen sensor core body; when the second electrode is contacted with hydrogen, the second electrode can adsorb and decompose the hydrogen into hydrogen atoms, the hydrogen atoms can diffuse and adsorb at the interface of the III-group nitride layer and the second electrode to form a dipole layer, so that capacitance change is caused, and the effects of safety, reliability and low detection lower limit are realized; meanwhile, the III group nitride surface is directly oxidized to form a III group oxide layer, namely the III group oxide layer is obtained by directly oxidizing the III group nitride, and a layer of III group oxide layer is obtained by redeposition on the III group nitride surface, so that the quality of the capacitive hydrogen sensor core is ensured; the second electrode is contacted with the III-group oxide layer, hydrogen atoms are also enabled to diffuse and be adsorbed at the interface of the III-group oxide layer and the second electrode, meanwhile, the III-group oxide layer directly interacts with the hydrogen atoms, the adsorption and desorption of the hydrogen atoms can reach an equilibrium state very fast, the characteristic of ultra-fast response speed is further achieved, and finally the capacitive hydrogen sensor core body is enabled to simultaneously have the advantages of low detection lower limit, fast response speed, safety and reliability.
Further, the forming a second electrode on the group iii oxide layer by magnetron sputtering or electron beam evaporation method further includes:
generating a first electrode on the end surface of the matrix, which is far away from the dielectric sheet, by a magnetron sputtering method or an electron beam evaporation method; or alternatively, the first and second heat exchangers may be,
and generating a first electrode on the III-group oxide layer by a magnetron sputtering method or an electron beam evaporation method, and controlling the first electrode and the second electrode to be arranged at intervals.
According to the preparation method of the capacitive hydrogen sensor core, the first electrode can be additionally arranged, the arrangement position of the first electrode is controlled in the preparation process, so that the performance that the capacitive hydrogen sensor core is low in detection lower limit, high in response speed and safe and reliable is guaranteed, meanwhile, the first electrode and the second electrode are arranged on the surface, away from the substrate, of the dielectric sheet, the sensitivity of the capacitive hydrogen sensor core is further improved, the thickness of the capacitive hydrogen sensor core is reduced, and miniaturization of the capacitive hydrogen sensor core is facilitated.
Further, the pretreatment of the dielectric sheet and oxidation of the pretreated dielectric sheet at the end of the dielectric sheet facing away from the substrate to obtain a group iii oxide layer include:
Ultrasonically cleaning a medium sheet made of III-group nitride material growing on a substrate for 5min sequentially through acetone, absolute ethyl alcohol and deionized water, and blow-drying the medium sheet by a nitrogen gun;
placing the medium sheet into a high temperature furnace, charging oxygen into the high temperature furnace, and maintaining the pressure to 1.01X10 5 Pa, heating the dielectric layer to 500-800 ℃ and preserving heat for 5-100min, and controlling the heating speed and the cooling speed to 10 ℃/min to obtain a III-group oxide layer; or, putting the dielectric sheet into sulfuric acid or hydrogen peroxide, and soaking for 3-30min to obtain a III-group oxide layer; or, the dielectric sheet is placed into an oxygen plasma instrument, the power of the oxygen plasma instrument is controlled to be 10-500W, the internal air pressure is 1-50Pa, and the treatment time is 1-100min, so that the III-group oxide layer is obtained.
According to the preparation method of the capacitive hydrogen sensor core, the III-group oxide layer is oxidized on the surface of the III-group nitride dielectric sheet which is not directly interacted with the hydrogen atoms, and the III-group oxide layer can interact with the hydrogen atoms, so that the response speed of the capacitive hydrogen sensor core can be effectively accelerated.
Further, the forming a second electrode on the group iii oxide layer by magnetron sputtering or electron beam evaporation includes:
Preparing palladium electrode or platinum electrode by magnetron sputtering method, wherein the target is palladium simple substance or platinum simple substance, the power supply is DC source, the working gas is argon or nitrogen, and the growth chamber is vacuumized to 1.0X10 -4 Pa, ignition and pre-sputteringDecontaminating for 3min, starting to sputter a palladium film or a platinum film, wherein the working air pressure is 0.4Pa, the flow of argon or nitrogen is 12sccm, the sputtering power is 5-200W, the sputtering time is 3min, and the sputtering thickness is 1-500nm; or alternatively, the first and second heat exchangers may be,
preparing platinum electrode or palladium electrode by electron beam evaporation, evaporating to obtain platinum particles or palladium particles, and vacuumizing the evaporation chamber to 1.0X10 -5 Pa, electron beam current 5A, vapor deposition time 5min, and obtaining platinum electrode or palladium electrode with thickness of 50 nm.
In the above method for manufacturing a capacitive hydrogen sensor core, the second electrode is formed on the group iii oxide layer (e.g., ga 2 O 3 Layer), and the preparation parameters of the second electrode can be rapidly and accurately controlled by adopting the magnetron sputtering method or the electron beam evaporation method, so that the quality of the capacitive hydrogen sensor core body is ensured.
Further, the generating the first electrode on the end surface of the substrate facing away from the dielectric sheet by using a magnetron sputtering method or an electron beam evaporation method includes:
Preparing a titanium-aluminum electrode by adopting a magnetron sputtering method, wherein the targets are a titanium single-substance target and an aluminum single-substance target, the power supply is a direct current source, the working gas is argon, and the growth cavity is vacuumized to 1.0 multiplied by 10 -4 Pa, starting and pre-sputtering for 3min to remove dirt, starting to sputter a titanium aluminum electrode, wherein the working air pressure is 0.4Pa, the sputtering power is 50W, the argon flow is 12sccm, the titanium film with the thickness of 15nm is sputtered, and then sputtering an aluminum film with the thickness of 60nm on the titanium film under the same condition; or alternatively, the first and second heat exchangers may be,
preparing nickel-gold electrode by magnetron sputtering, wherein the target material is nickel simple substance and Jin Shanzhi, the power supply is DC source, the working gas is argon, and the growth chamber is vacuumized to 1.0X10 -4 Pa, starting and pre-sputtering for 3min to remove dirt, starting to sputter a nickel film, wherein the working air pressure is 0.4Pa, the sputtering power is 50W, the argon flow is 12sccm, and sputtering a nickel film of 10 nm; then sputtering a gold film on the nickel film, wherein the working air pressure is 0.4Pa, the sputtering power is 30W, the argon flow is 12sccm, and the thickness of the gold film is 80nm; or alternatively, the first and second heat exchangers may be,
the nickel-gold electrode is prepared by an electron beam evaporation method, the evaporation source is nickel simple substance and Jin Shanzhi,depositing a nickel film with the thickness of 10nm, and then depositing a gold film with the thickness of 100nm on the nickel film, wherein the evaporation cavity is vacuumized to 1.0x10 - 5 Pa, electron beam current 5A, sputtering time of the nickel film of 3min, sputtering time of the gold film of 10min.
According to the preparation method of the capacitive hydrogen sensor core, the first electrode is additionally arranged, so that the operation stability and the service life of the capacitive hydrogen sensor core are further guaranteed; the first electrode is prepared by adopting a magnetron sputtering method and an electron beam evaporation method, so that the preparation parameters of the first electrode can be conveniently controlled, and the quality of the capacitive hydrogen sensor is ensured.
Further, generating a first electrode on the group iii oxide layer by a magnetron sputtering method or an electron beam evaporation method, and controlling the first electrode and the second electrode to be arranged at intervals, including:
preparing a palladium electrode or a platinum electrode which is arranged at intervals with the second electrode by adopting a magnetron sputtering method, wherein a target material is a palladium simple substance or a platinum simple substance, a power supply is a direct current source, working gas is argon, and a growth cavity is vacuumized to 1.0 multiplied by 10 -4 Pa, starting and pre-sputtering for 3min to remove dirt, starting to sputter a palladium film or a platinum film, wherein the working air pressure is 0.66Pa, the flow of argon or nitrogen is 12sccm, the sputtering power is 70W, and the sputtering time is 2min; or alternatively, the first and second heat exchangers may be,
preparing platinum electrode or palladium electrode spaced from the second electrode by electron beam evaporation, evaporating to obtain platinum particles or palladium particles, and vacuumizing the evaporation chamber to 1.0X10 -5 Pa, electron beam current was 8A, vapor deposition time was 10min, and a platinum electrode or palladium electrode having a thickness of 50nm was obtained.
According to the preparation method of the capacitive hydrogen sensor core, the first electrode and the second electrode are simultaneously arranged on the III-group oxide layer, and the first electrode is controlled to be made of the same hydrogen sensitive material as the second electrode, so that the capacitive hydrogen sensor obtained by the method is provided with the two electrodes which can interact with hydrogen atoms to double output signals, and the sensor has higher sensitivity and lower detection lower limit.
The invention solves the technical problem by adopting another technical scheme as follows: a capacitive hydrogen sensor, comprising: the capacitive hydrogen sensor core body is prepared by the preparation method of the capacitive hydrogen sensor core body.
According to the capacitive hydrogen sensor, the capacitive hydrogen sensor core body prepared by the capacitive hydrogen sensor preparation method provided by the application is adopted, so that the performances of low detection lower limit, high response speed, safety and reliability can be simultaneously considered; specifically, the III-group nitride is adopted as a dielectric sheet, so that the safety and reliability of the capacitor hydrogen sensor can be effectively ensured; through oxidizing the III group oxide layer directly on the surface of the III group nitride, when the second electrode adsorbs and decomposes hydrogen into hydrogen atoms, the hydrogen atoms are diffused and adsorbed at the interface of the III group oxide layer and the second electrode, and the III group oxide layer and the second electrode interact with the hydrogen atoms at the same time, so that the response speed of the capacitive hydrogen sensor is effectively improved, and the detection lower limit of the capacitive hydrogen sensor is reduced.
The beneficial effects are that:
the invention provides a capacitive hydrogen sensor core, a preparation method thereof, a capacitive hydrogen sensor and a capacitive hydrogen sensor core, wherein the capacitive hydrogen sensor core comprises: the substrate, the dielectric sheet and the second electrode are sequentially arranged from bottom to top; wherein the substrate is provided as a layer of conductive material; the second electrode is arranged as a hydrogen sensitive layer; the dielectric sheet is a III-nitride layer, and the end face of the dielectric sheet, which is away from the substrate, is oxidized into a III-oxide layer. It can be understood that the dielectric sheet is arranged as a III-nitride layer, III-nitride is used as an isolation layer of the capacitor, and the second electrode, the conductive material layer and the dielectric sheet form a capacitive hydrogen sensor core body; when the second electrode is contacted with hydrogen, the second electrode can adsorb and decompose the hydrogen into hydrogen atoms, the hydrogen atoms are diffused and adsorbed at the interface of the III-nitride layer and the second electrode to form a dipole layer, so that capacitance change is caused, and the effects of safety, reliability and low detection lower limit are realized; meanwhile, a III group oxide layer is formed on the surface of the III group nitride by directly oxidizing the area on the surface of the III group nitride, namely, the III group oxide layer is obtained by directly oxidizing the III group nitride, and a III group oxide layer is not obtained by redeposition on the surface of the III group nitride, so that the quality of the capacitive hydrogen sensor core is ensured; the second electrode is contacted with the III-group oxide layer, hydrogen atoms are also enabled to diffuse and be adsorbed at the interface of the III-group oxide layer and the second electrode, meanwhile, the III-group oxide layer directly interacts with the hydrogen atoms, the adsorption and desorption of the hydrogen atoms can reach an equilibrium state very fast, the characteristic of ultra-fast response speed is further achieved, and finally the capacitive hydrogen sensor core body is enabled to simultaneously have the advantages of low detection lower limit, fast response speed, safety and reliability.
Drawings
FIG. 1 is a schematic diagram of a capacitive hydrogen sensor provided in the present invention;
FIG. 2 is a schematic cross-sectional view of a dielectric sheet of a capacitive hydrogen sensor provided in the present invention;
FIG. 3 is a schematic diagram of a variation of the capacitive hydrogen sensor provided in the present invention;
FIG. 4 is a schematic diagram showing a variation of the capacitive hydrogen sensor according to the preferred embodiment of the present invention;
FIG. 5 is a schematic flow chart of a method for manufacturing a capacitive hydrogen sensor provided in the present invention;
FIG. 6 is a schematic flow chart of a method for manufacturing a capacitive hydrogen sensor according to the present invention;
FIG. 7 is a schematic flow chart of a preferred embodiment of a dielectric sheet of a method for manufacturing a capacitive hydrogen sensor according to the present invention;
FIG. 8 is a schematic flow chart of a preferred embodiment of a dielectric sheet of a method for manufacturing a capacitive hydrogen sensor according to the present invention;
FIG. 9 is a schematic flow chart of a dielectric sheet of a method for manufacturing a capacitive hydrogen sensor according to the present invention;
reference numerals illustrate:
10. a capacitive hydrogen sensor core; 11. a base; 12. a media sheet; 13. a second electrode; 14. a first electrode; 15. a group III nitride layer; 16. group iii oxide layers.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more clear and clear, the present invention will be further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.
Hydrogen element on earth is very abundant, and hydrogen can be prepared through water electrolysis, photocatalysis, chemical process and the like. The hydrogen energy source is wide, green and renewable, and is expected to become the most important energy form in the near future to be widely applied to the fields of hydrogen fuel cell automobiles, aerospace, chemical industry, electrons and the like. However, hydrogen is colorless, odorless, transparent, and not easily found even if leaked during production, transportation, and use. Hydrogen is a flammable and explosive gas, which is prone to combustion or explosion accidents when the volume concentration in the air is 4-75%. Therefore, a sensor capable of rapidly detecting the concentration of hydrogen is required to perform early warning and prediction on the leakage of hydrogen, and meanwhile, the hydrogen is used as an important marker of digestive tract diseases, and the hydrogen sensor is also an extremely important core component in diagnosis of expiratory diseases in medical treatment. These applications require hydrogen sensors with low lower detection limit LOD and rapid detection capability to discover hydrogen leakage and take relevant protective measures as early as possible.
Currently, hydrogen sensors mainly include optical fiber sensing type, metal semiconductor oxide resistor type, electrochemical type, catalytic combustion type, field effect transistor type, capacitance type and the like. The optical fiber sensing detector has good safety, but mainly tests high-concentration hydrogen; the metal-semiconductor oxide resistance sensor has simple structure, low cost and long response time, and can test low-concentration hydrogen; the catalytic combustion type sensor is applied to partial hydrogen fuel cell automobiles at present, has ultra-fast response speed, high stability and wide detection range, but can only detect hydrogen with the concentration of more than 1000ppm generally, and cannot detect hydrogen with low concentration; the capacitive sensor has the excellent characteristics of small baseline drift, insensitivity to environmental change and the like, does not generate electric sparks during operation, can not ignite and detonate high-concentration hydrogen even if the high-concentration hydrogen leaks, and has high safety and reliability. Currently, the commercial sensors have the defects of high detection lower limit, poor safety, low response speed (more than 3 s) and the like.
Based on the problems that the hydrogen sensor in the prior art cannot achieve low detection lower limit, high response speed and safety and reliability, the invention provides a capacitive hydrogen sensor core, a preparation method thereof and a capacitive hydrogen sensor, wherein the dielectric sheet is set to be a III-group nitride layer, the III-group nitride is used as an isolation layer of a capacitor, and the second electrode, the conductive material layer and the dielectric sheet form the capacitive hydrogen sensor core; when the second electrode is contacted with hydrogen, the second electrode can adsorb and decompose the hydrogen into hydrogen atoms, the hydrogen atoms can diffuse and adsorb at the interface of the III-group nitride layer and the second electrode to form a dipole layer, so that capacitance change is caused, and the effects of safety, reliability and low detection lower limit are realized; meanwhile, oxidizing the surface area of the III nitride, which is away from the substrate, directly to form a III oxide layer on the surface of the III nitride, namely, the III oxide layer is obtained by directly oxidizing the III nitride, and a layer of III oxide layer is obtained by redeposition on the surface of the III nitride, so that the quality of the capacitive hydrogen sensor core is ensured; the second electrode contacts with the III group oxide layer, so that hydrogen atoms are diffused and adsorbed at the interface of the III group oxide layer and the second electrode, and meanwhile, the III group oxide layer directly interacts with the hydrogen atoms, so that the adsorption and desorption of the hydrogen atoms can reach an equilibrium state rapidly, the characteristic of ultra-fast response speed is further realized, and finally, the capacitive hydrogen sensor core body has the advantages of low detection lower limit, high response speed and safety and reliability, and particularly, the embodiment is described in detail.
Referring to fig. 1 and fig. 2 in combination, a first embodiment of the present invention provides a capacitive hydrogen sensor core 10, where the capacitive hydrogen sensor core 10 has low detection lower limit, high response speed, and safe and reliable performance; specifically, the capacitive hydrogen sensor core 10 includes: a substrate 11, a dielectric sheet 12 and a second electrode 13 which are arranged in sequence from bottom to top; the dielectric sheet 12 is arranged on the upper end surface of the base 11 along the height direction; the second electrode 13 is arranged on the surface of the dielectric sheet 12 facing away from the substrate 11; wherein the substrate 11 is provided as a layer of conductive material; the dielectric sheet 12 is provided as a group iii nitride layer 15, and the end face of the dielectric sheet 12 facing away from the substrate is oxidized to a group iii oxide layer 16; the second electrode 13 is provided as a hydrogen sensitive layer.
It can be understood that by providing the second electrode 13 as a hydrogen-sensitive layer, the second electrode 13 adsorbs and decomposes hydrogen gas into hydrogen atoms when in contact with the hydrogen gas; meanwhile, the substrate 11 is set as a conductive material layer, and then the substrate 11 forms an electrode, the dielectric sheet 12 is set as a III nitride layer 15, III nitride is used as an isolation layer of a capacitor, the second electrode 13, the conductive material layer 11 and the dielectric sheet 12 form a capacitive hydrogen sensor core 10, hydrogen atoms are diffused and adsorbed at the interface of the III nitride layer 15 and the second electrode 13, a dipole layer is formed, so that capacitance change is caused, and the effects of safety, reliability and low detection lower limit are further realized; simultaneously, directly oxidizing the area of the III-nitride surface to form a III-oxide layer 16 on the III-nitride surface; the second electrode 13 is in contact with the group iii oxide layer 16, so that hydrogen atoms can diffuse and be adsorbed at the interface of the group iii oxide layer 16 and the second electrode 13, and meanwhile, the group iii oxide layer 16 directly interacts with the hydrogen atoms, so that the adsorption and desorption of the hydrogen atoms can reach an equilibrium state very quickly, and the characteristic of ultra-fast response speed is further realized, and finally, the capacitive hydrogen sensor core 10 is enabled to simultaneously have the advantages of low detection lower limit (less than or equal to 500 ppb), fast response speed (less than or equal to 3 s) and safe and reliable performance.
In some preferred embodiments, the substrate 11 is provided as a monocrystalline silicon wafer or a silicon carbide wafer, and has a thickness of 0.001-3 mm.
It can be appreciated that the substrate 11 may have a conductive effect, and further may cooperate with the second electrode 13 and the dielectric sheet 12 to form the capacitive hydrogen sensor core 10, so as to facilitate miniaturization of the capacitive hydrogen sensor core 10 while ensuring performance of the capacitive hydrogen sensor core 10.
Referring to fig. 3 in combination, in some preferred embodiments, the capacitive hydrogen sensor core 10 further includes a first electrode 14, where the first electrode 14 is disposed on an end surface of the substrate 11 facing away from the dielectric sheet 12.
It will be appreciated that the substrate in this embodiment may also be provided as a layer of non-conductive material, such as a sapphire layer; at this time, the first electrode 14 is additionally arranged, so that the continuous operation of the capacitive hydrogen sensor core 10 can be ensured; thereby effectively improving the stability of the capacitive hydrogen sensor core 10.
Referring to fig. 4 in combination, in some preferred embodiments, the first electrode 14 is disposed on a surface of the dielectric sheet 12 facing away from the substrate 11, and the first electrode 14 is spaced apart from the second electrode 13.
It can be appreciated that, by controlling the setting position of the first electrode 14, the capacitive hydrogen sensor core 10 is further guaranteed to have low detection lower limit, high response speed and safe and reliable performance, and meanwhile, the first electrode 14 and the second electrode 13 are both arranged on the surface of the dielectric sheet 12, which is away from the substrate 11, so that the sensitivity of the capacitive hydrogen sensor core 10 is further improved, the thickness of the capacitive hydrogen sensor core 10 is reduced, and miniaturization of the capacitive hydrogen sensor core 10 is facilitated.
In other preferred embodiments, the dielectric pellet 12 includes the III-nitride layer 15 including a GaN layer, al x Ga 1-x N layer or In x Ga 1-x An N layer; the group III oxide layer 16 includes Ga 2 O 3 Layer, al x Ga 2-x O 3 Layer or In x Ga 2-x O 3 A layer, wherein theX is 0-0.5; the thickness of the dielectric sheet 12 is 0.02-10 μm, and the Ga 2 O 3 The thickness of the layer is 2-30 nm; the first electrode 14 is an aluminum electrode, a gold electrode, a titanium aluminum electrode, a nickel-gold electrode, a chromium-gold electrode, a copper-gold electrode, a titanium-gold electrode, a platinum electrode or a palladium electrode, and the thickness of the first electrode 14 is 1-500 nm; the second electrode 13 is a platinum electrode or a palladium electrode, and the thickness of the second electrode 13 is 1-1000 nm.
It can be understood that the second electrode 13 is further provided as a hydrogen sensitive layer by controlling the material of the second electrode 13; the first electrode 14 and the second electrode 13 may be both provided as a hydrogen sensitive layer, so that the sensitivity of the capacitive hydrogen sensor core 10 may be further improved.
In other preferred embodiments, the dielectric sheet 12 is provided as a GaN layer, and the side of the GaN layer in contact with the second electrode 13 is oxidized to Ga 2 O 3 A layer; the thickness of the dielectric sheet 12 is 0.02-10 μm, and the Ga 2 O 3 The thickness of the layer is 2-30 nm.
Referring to fig. 5 in combination, a method for manufacturing a capacitive hydrogen sensor core is further provided in a second embodiment of the present invention, which includes:
s11, generating a dielectric sheet made of III-group nitride material on a conductive substrate;
step S12, preprocessing the dielectric sheet, and oxidizing the preprocessed dielectric sheet at one end, which is far away from the matrix, to obtain a III-group oxide layer;
and S13, generating a second electrode on the III-family oxide layer by a magnetron sputtering method or an electron beam evaporation method.
It can be understood that the dielectric sheet is arranged as a III-nitride layer, III-nitride is used as an isolation layer of the capacitor, and the second electrode, the conductive material layer and the dielectric sheet form a capacitive hydrogen sensor core body; when the second electrode is contacted with hydrogen, the second electrode can adsorb and decompose the hydrogen into hydrogen atoms, the hydrogen atoms can diffuse and adsorb at the interface of the III-group nitride layer and the second electrode to form a dipole layer, so that capacitance change is caused, and the effects of safety, reliability and low detection lower limit are realized; meanwhile, oxidizing the surface area of the III nitride away from the conductive material layer directly to form a III oxide layer on the surface of the III nitride, namely, the III oxide layer is obtained by directly oxidizing the III nitride instead of redepositing a layer of III oxide layer on the surface of the III nitride, so that the quality of the capacitive hydrogen sensor core is ensured; the second electrode is contacted with the III-group oxide layer, hydrogen atoms are also enabled to diffuse and be adsorbed at the interface of the III-group oxide layer and the second electrode, meanwhile, the III-group oxide layer directly interacts with the hydrogen atoms, the adsorption and desorption of the hydrogen atoms can reach an equilibrium state very fast, the characteristic of ultra-fast response speed is further achieved, and finally the capacitive hydrogen sensor core body is enabled to simultaneously have the advantages of low detection lower limit, fast response speed, safety and reliability.
Referring to fig. 6 in combination, in other preferred embodiments, step S13 further includes step S14a, where step S14a includes:
and generating a first electrode on the end surface of the substrate, which is far away from the dielectric sheet, by a magnetron sputtering method or an electron beam evaporation method.
Referring to fig. 6 in combination, in other preferred embodiments, step S13 further includes step S14b, where step S14b includes:
and generating a first electrode on the III-group oxide layer by a magnetron sputtering method or an electron beam evaporation method, and controlling the first electrode and the second electrode to be arranged at intervals.
It can be understood that the first electrode can be additionally arranged, the arrangement position of the first electrode is controlled in the preparation process, so that the performance that the capacitance type hydrogen sensor core has low detection lower limit, high response speed and safety and reliability is guaranteed, meanwhile, the first electrode and the second electrode are arranged on the surface of the medium sheet, which is away from the substrate, so that the sensitivity of the capacitance type hydrogen sensor core is further improved, the thickness of the capacitance type hydrogen sensor core is reduced, and the miniaturization of the capacitance type hydrogen sensor core is facilitated.
Referring to fig. 7 in combination, in some embodiments, the step S12 includes:
step S121, sequentially ultrasonically cleaning a medium sheet made of III-group nitride materials growing on a substrate by using acetone, absolute ethyl alcohol and deionized water for 5min, and blow-drying the medium sheet by using a nitrogen gun;
step S122a, placing the medium sheet into a high temperature furnace, and charging oxygen into the high temperature furnace and maintaining the pressure to 1.01X10 5 Pa, heating the dielectric layer to 500-800 ℃ and preserving heat for 5-100min, and controlling the heating speed and the cooling speed to 10 ℃/min to obtain the III-group oxide layer.
It will be appreciated that the substrate and the media sheet thereon are subjected to a desmutting treatment in advance; and oxidizing the III-group oxide layer on the surface of the III-group nitride dielectric sheet in a high-temperature oxidation mode, wherein the III-group oxide layer can interact with the hydrogen atoms, so that the response speed of the capacitive hydrogen sensor core can be effectively increased.
In some embodiments, the step S12 includes:
step S121, sequentially ultrasonically cleaning a GaN-material dielectric sheet growing on a substrate by using acetone, absolute ethyl alcohol and deionized water for 5min, and drying the dielectric sheet by using a nitrogen gun;
Step S122a, placing the medium sheet into a high temperature furnace, and charging oxygen into the high temperature furnace and maintaining the pressure to 1.01X10 5 Pa, heating the dielectric layer to 500-800 ℃ and preserving heat for 5-100min, and controlling the heating speed and the cooling speed to 10 ℃/min to obtain Ga 2 O 3 A layer.
It will be appreciated that the substrate and the media sheet thereon are subjected to a desmutting treatment in advance; then oxidizing Ga on the surface of the GaN dielectric sheet by a high-temperature oxidation mode 2 O 3 Layer of Ga 2 O 3 The layer can interact with the hydrogen atoms, so that the response speed of the capacitive hydrogen sensor core body can be effectively accelerated.
Referring to fig. 8 in combination, in some embodiments, the step S12 includes:
step S121, sequentially ultrasonically cleaning a GaN-material dielectric sheet growing on a substrate by using acetone, absolute ethyl alcohol and deionized water for 5min, and drying the dielectric sheet by using a nitrogen gun;
step S122b, soaking the dielectric sheet in sulfuric acid or hydrogen peroxide for 3-30min to obtain Ga 2 O 3 A layer.
It will be appreciated that the substrate and the media sheet thereon are subjected to a desmutting treatment in advance; then oxidizing Ga on the surface of the GaN dielectric sheet by a chemical solution oxidation mode 2 O 3 Layer of Ga 2 O 3 The layer can interact with the hydrogen atoms, so that the response speed of the capacitive hydrogen sensor core body can be effectively accelerated.
Referring to fig. 9 in combination, in other embodiments, the step S12 includes:
step S121, sequentially ultrasonically cleaning a GaN-material dielectric sheet growing on a substrate by using acetone, absolute ethyl alcohol and deionized water for 5min, and drying the dielectric sheet by using a nitrogen gun;
step S122c, placing the dielectric sheet into an oxygen plasma instrument, controlling the power of the oxygen plasma instrument to be 10-500W, the internal air pressure to be 1-50Pa, and the treatment time to be 1-100min to obtain Ga 2 O 3 A layer.
It will be appreciated that the substrate and the media sheet thereon are subjected to a desmutting treatment in advance; then oxidizing Ga on the surface of the GaN dielectric sheet by a plasma oxidation mode 2 O 3 Layer of Ga 2 O 3 The layer can interact with the hydrogen atoms, so that the response speed of the capacitive hydrogen sensor core body can be effectively accelerated.
In some embodiments, the step S13 includes:
preparing palladium electrode by magnetron sputtering method, wherein the target material is palladium simple substance, the power supply is DC source, the working gas is argon or nitrogen, and the growth chamber is vacuumized to 1.0X10 -4 Pa, ignition andpre-sputtering for 3min to remove dirt, starting to sputter the palladium film, wherein the working air pressure is 0.4Pa, the flow of argon or nitrogen is 12sccm, the sputtering power is 5-200W, the sputtering time is 3min, and the sputtering thickness is 1-500nm.
It can be understood that the second electrode is generated on the III-group oxide layer, and the preparation parameters of the second electrode can be rapidly and accurately controlled by adopting the magnetron sputtering method, so that the quality of the capacitive hydrogen sensor core body is ensured.
In some embodiments, the step S13 includes:
preparing palladium electrode by magnetron sputtering method, wherein the target material is platinum simple substance, the power supply is DC source, the working gas is argon or nitrogen, and the growth chamber is vacuumized to 1.0X10 -4 Pa, starting and pre-sputtering for 3min to remove dirt, starting to sputter a platinum film, wherein the working air pressure is 0.4Pa, the flow of argon or nitrogen is 12sccm, the sputtering power is 5-200W, the sputtering time is 3min, and the sputtering thickness is 1-500nm.
It can be understood that the second electrode is generated on the III-group oxide layer, and the preparation parameters of the second electrode can be rapidly and accurately controlled by adopting the magnetron sputtering method, so that the quality of the capacitive hydrogen sensor core body is ensured.
In other embodiments, the step S13 may further include:
preparing platinum electrode by electron beam evaporation, evaporating to obtain platinum particles, and vacuumizing the evaporation chamber to 1.0X10 -5 Pa, electron beam current 5A, vapor deposition time 5min, and obtaining platinum electrode with thickness of 50 nm.
It can be understood that the second electrode is formed on the group iii oxide layer, and the preparation parameters of the second electrode can be rapidly and accurately controlled by adopting the electron beam evaporation method, so that the quality of the capacitive hydrogen sensor core is ensured.
In other embodiments, the step S13 may further include:
preparing palladium electrode by electron beam evaporation, evaporating to obtain palladium particles, and vacuumizing the evaporation chamber to 1.0X10 -5 Pa, electron beam current 5A, vapor deposition time5min, a palladium electrode with a thickness of 50nm was obtained.
It can be understood that the second electrode is formed on the group iii oxide layer, and the preparation parameters of the second electrode can be rapidly and accurately controlled by adopting the electron beam evaporation method, so that the quality of the capacitive hydrogen sensor core is ensured.
In some embodiments, the step S14a includes:
preparing a titanium-aluminum electrode by adopting a magnetron sputtering method, wherein the targets are a titanium single-substance target and an aluminum single-substance target, the power supply is a direct current source, the working gas is argon, and the growth cavity is vacuumized to 1.0 multiplied by 10 -4 Pa, starting and pre-sputtering for 3min to remove dirt, starting to sputter the titanium aluminum electrode, wherein the working air pressure is 0.4Pa, the sputtering power is 50W, the argon flow is 12sccm, the titanium film with the thickness of 15nm is sputtered, and then the aluminum film with the thickness of 60nm is sputtered on the titanium film under the same condition.
It can be understood that by additionally arranging the first electrode, the operation stability and the service life of the capacitive hydrogen sensor core are further ensured; the first electrode is prepared by adopting a magnetron sputtering method, so that the preparation parameters of the first electrode can be conveniently controlled, and the quality of the capacitive hydrogen sensor is ensured.
In other embodiments, the step S14a includes:
preparing nickel-gold electrode by magnetron sputtering, wherein the target material is nickel simple substance and Jin Shanzhi, the power supply is DC source, the working gas is argon, and the growth chamber is vacuumized to 1.0X10 -4 Pa, starting and pre-sputtering for 3min to remove dirt, starting to sputter a nickel film, wherein the working air pressure is 0.4Pa, the sputtering power is 50W, the argon flow is 12sccm, and sputtering a nickel film of 10 nm; then a layer of gold film is sputtered on the nickel film, the working air pressure is 0.4Pa, the sputtering power is 30W, the argon flow is 12sccm, and the thickness of the gold film is 80nm.
It can be understood that by additionally arranging the first electrode, the operation stability and the service life of the capacitive hydrogen sensor core are further ensured; the first electrode is prepared by adopting a magnetron sputtering method, so that the preparation parameters of the first electrode can be conveniently controlled, and the quality of the capacitive hydrogen sensor is ensured.
In other embodiments, the step S14a includes:
preparing nickel-gold electrode by electron beam evaporation method, wherein the evaporation source is nickel simple substance and Jin Shanzhi, depositing nickel film with thickness of 10nm, and depositing gold film with thickness of 100nm on the nickel film, wherein the evaporation cavity is vacuumized to 1.0X10 - 5 Pa, electron beam current 5A, sputtering time of the nickel film of 3min, sputtering time of the gold film of 10min.
It can be understood that by additionally arranging the first electrode, the operation stability and the service life of the capacitive hydrogen sensor core are further ensured; the first electrode is prepared by adopting an electron beam evaporation method, so that the preparation parameters of the first electrode can be conveniently controlled, and the quality of the capacitive hydrogen sensor is ensured.
In some preferred embodiments, step S14b includes:
Preparing palladium electrode spaced from the second electrode by magnetron sputtering, wherein the target material is palladium simple substance, the power supply is direct current source, the working gas is argon, and the growth cavity is vacuumized to 1.0×10 -4 Pa, starting and pre-sputtering for 3min to remove dirt, starting to sputter the palladium film, wherein the working air pressure is 0.66Pa, the flow of argon or nitrogen is 12sccm, the sputtering power is 70W, and the sputtering time is 2min.
It can be understood that the first electrode and the second electrode are simultaneously arranged on the III-group oxide layer, and the first electrode is controlled to be made of the same hydrogen sensitive material as the second electrode, so that the capacitive hydrogen sensor obtained by the method has two electrodes which can interact with hydrogen atoms to double output signals, and the sensor has higher sensitivity and lower detection lower limit.
In some preferred embodiments, step S14b further comprises:
preparing platinum electrode spaced from the second electrode by magnetron sputtering, wherein the target material is platinum simple substance, the power supply is DC source, the working gas is argon, and the growth chamber is vacuumized to 1.0×10 -4 Pa, starting and pre-sputtering for 3min to remove dirt, starting to sputter a platinum film, wherein the working air pressure is 0.66Pa, the flow of argon or nitrogen is 12sccm, the sputtering power is 70W, and the sputtering time is 2min.
It can be understood that the first electrode and the second electrode are simultaneously arranged on the III-group oxide layer, and the first electrode is controlled to be made of the same hydrogen sensitive material as the second electrode, so that the capacitive hydrogen sensor obtained by the method has two electrodes which can interact with hydrogen atoms to double output signals, and the sensor has higher sensitivity and lower detection lower limit.
In some preferred embodiments, step S14b includes:
preparing platinum electrode spaced from the second electrode by electron beam evaporation, evaporating to obtain platinum particles, and vacuumizing the evaporation chamber to 1.0X10 -5 Pa, electron beam current was 8A, vapor deposition time was 10min, and a platinum electrode having a thickness of 50nm was obtained.
It can be understood that the first electrode and the second electrode are simultaneously arranged on the III-group oxide layer, and the first electrode is controlled to be made of the same hydrogen sensitive material as the second electrode, so that the capacitive hydrogen sensor obtained by the method has two electrodes which can interact with hydrogen atoms to double output signals, and the sensor has higher sensitivity and lower detection lower limit.
In some preferred embodiments, step S14b includes:
preparing palladium electrode spaced from the second electrode by electron beam evaporation, evaporating to obtain palladium particles, and vacuumizing the evaporation chamber to 1.0X10 -5 Pa, electron beam current was 8A, vapor deposition time was 10min, and a palladium electrode having a thickness of 50nm was obtained.
It can be understood that the first electrode and the second electrode are simultaneously arranged on the III-group oxide layer, and the first electrode is controlled to be made of the same hydrogen sensitive material as the second electrode, so that the capacitive hydrogen sensor obtained by the method has two electrodes which can interact with hydrogen atoms to double output signals, and the sensor has higher sensitivity and lower detection lower limit.
There is also provided in a third embodiment of the present invention a capacitive hydrogen sensor including: the capacitive hydrogen sensor core obtained by the preparation method of the capacitive hydrogen sensor core provided in the embodiment of the invention is prepared.
It can be understood that the capacitive hydrogen sensor core body prepared by the capacitive hydrogen sensor preparation method provided by the application can be used for simultaneously taking the performances of low detection lower limit, high response speed and safety and reliability into consideration; specifically, the III-group nitride is adopted as a dielectric sheet, so that the safety and reliability of the capacitor hydrogen sensor can be effectively ensured; through oxidizing the III group oxide layer directly on the surface of the III group nitride, when the second electrode adsorbs and decomposes hydrogen into hydrogen atoms, the hydrogen atoms are diffused and adsorbed at the interface of the III group oxide layer and the second electrode, and the III group oxide layer and the second electrode interact with the hydrogen atoms at the same time, so that the response speed of the capacitive hydrogen sensor is effectively improved, and the detection lower limit of the capacitive hydrogen sensor is reduced.
In summary, the capacitive hydrogen sensor core, the preparation method thereof, the capacitive hydrogen sensor and the capacitive hydrogen sensor provided by the invention comprise: the substrate, the dielectric sheet and the second electrode are sequentially arranged from bottom to top; wherein the substrate is provided as a layer of conductive material; the second electrode is arranged as a hydrogen sensitive layer; the dielectric sheet is a III-nitride layer, and the end face of the dielectric sheet, which is away from the substrate, is oxidized into a III-oxide layer. It can be understood that the dielectric sheet is arranged as a III-nitride layer, III-nitride is used as an isolation layer of the capacitor, and the second electrode, the conductive material layer and the dielectric sheet form a capacitive hydrogen sensor core body; when the second electrode is contacted with hydrogen, the second electrode can adsorb and decompose the hydrogen into hydrogen atoms, the hydrogen atoms can diffuse and adsorb at the interface of the III-group nitride layer and the second electrode to form a dipole layer, so that capacitance change is caused, and the effects of safety, reliability and low detection lower limit are realized; meanwhile, the III group nitride surface is directly oxidized to form a III group oxide layer, namely the III group oxide layer is obtained by directly oxidizing the III group nitride, and a layer of III group oxide layer is obtained by redeposition on the III group nitride surface, so that the quality of the capacitive hydrogen sensor core is ensured; the second electrode is contacted with the III-group oxide layer, hydrogen atoms are also enabled to diffuse and be adsorbed at the interface of the III-group oxide layer and the second electrode, meanwhile, the III-group oxide layer directly interacts with the hydrogen atoms, the adsorption and desorption of the hydrogen atoms can reach an equilibrium state very fast, the characteristic of ultra-fast response speed is further achieved, and finally the capacitive hydrogen sensor core body is enabled to simultaneously have the advantages of low detection lower limit, fast response speed, safety and reliability.
It is to be understood that the invention is not limited in its application to the examples described above, but is capable of modification and variation in light of the above teachings by those skilled in the art, and that all such modifications and variations are intended to be included within the scope of the appended claims.
Claims (5)
1. A capacitive hydrogen sensor core, comprising:
the substrate, the dielectric sheet and the second electrode are sequentially arranged from bottom to top;
wherein the substrate is provided as a layer of conductive material; the second electrode is arranged as a hydrogen sensitive layer; the dielectric sheet is a III-nitride layer, the end face of the dielectric sheet, which is away from the substrate, is oxidized into a III-oxide layer, and the III-oxide layer is in contact with the second electrode;
the capacitive hydrogen sensor core further comprises a first electrode;
the first electrode is arranged on the surface of the dielectric sheet, which is away from the matrix, and the first electrode and the second electrode are arranged at intervals;
oxidizing a region of a group iii nitride surface, forming a group iii oxide layer on the group iii nitride surface; the second electrode is contacted with the III-group oxide layer, hydrogen atoms are also diffused and adsorbed at the interface of the III-group oxide layer and the second electrode, and meanwhile, the III-group oxide layer directly interacts with the hydrogen atoms, so that the adsorption and desorption of the hydrogen atoms can reach an equilibrium state quickly;
A method of making a capacitive hydrogen sensor core comprising:
generating a dielectric sheet made of III-nitride material on a conductive substrate;
pretreating the dielectric sheet, and oxidizing the pretreated dielectric sheet at one end, which is far away from the matrix, to obtain a III-group oxide layer;
generating a second electrode on the III-group oxide layer by a magnetron sputtering method or an electron beam evaporation method;
generating a first electrode on the III-group oxide layer by a magnetron sputtering method or an electron beam evaporation method, and controlling the first electrode and the second electrode to be arranged at intervals;
the forming of the second electrode on the III-group oxide layer by the magnetron sputtering method or the electron beam evaporation method comprises the following steps:
preparing palladium or platinum electrode by magnetron sputtering, wherein the target material is palladium simple substance or platinum simple substance, the power supply is direct current source, the working gas is argon or nitrogen, and the growth chamber is vacuumized to 1.0X10 -4 Pa, starting and pre-sputtering for 3 min to remove dirt, starting to sputter a palladium film or a platinum film, wherein the working air pressure is 0.4 Pa, the flow of argon or nitrogen is 12 sccm, the sputtering power is 5-200W, the sputtering time is 3 min, and the sputtering thickness is 1-500 nm; or alternatively, the first and second heat exchangers may be,
preparing platinum electrode or palladium electrode by electron beam evaporation, evaporating to obtain platinum particles or palladium particles, and vacuumizing the evaporation chamber to 1.0X10 -5 Pa, electron beam current is 5A, vapor deposition time is 5 min, and a platinum electrode or palladium electrode with thickness of 50 nm is obtained;
generating a first electrode on the III-group oxide layer by a magnetron sputtering method or an electron beam evaporation method, and controlling the interval between the first electrode and the second electrode, wherein the method comprises the following steps:
preparing a palladium electrode or a platinum electrode which is arranged at intervals with the second electrode by adopting a magnetron sputtering method, wherein a target material is a palladium simple substance or a platinum simple substance, a power supply is a direct current source, working gas is argon, and a growth cavity is vacuumized to 1.0 multiplied by 10 -4 Pa, starting and pre-sputtering for 3 min to remove dirt, starting to sputter a palladium film or a platinum film, wherein the working air pressure is 0.66 and Pa, the flow rate of argon or nitrogen is 12 sccm, the sputtering power is 70 and W, and the sputtering time is 2 min; or alternatively, the first and second heat exchangers may be,
preparing platinum electrode or palladium electrode spaced from the second electrode by electron beam evaporation, evaporating to obtain platinum particles or palladium particles, and vacuumizing the evaporation chamber to 1.0X10 -5 Pa, an electron beam current of 8A, a vapor deposition time of 10 min, and a platinum electrode or a palladium electrode having a thickness of 50 nm were obtained.
2. A capacitive hydrogen sensor core according to claim 1, characterized in that,
the substrate is set to be monocrystalline silicon wafer or carborundum silicon wafer, and the thickness is 0.001-3 mm.
3. A capacitive hydrogen sensor core according to claim 2, characterized in that,
the III-nitride layer comprises a GaN layer and Al x Ga 1-x N layer or In x Ga 1-x An N layer; the III-oxide layer comprises Ga 2 O 3 Layer, al x Ga 2-x O 3 Layer or In x Ga 2-x O 3 A layer, wherein X is 0-0.5;
the thickness of the dielectric sheet is 0.02-10 mu m, and the thickness of the III-group oxide layer is 2-30 nm;
the first electrode is an aluminum electrode, a gold electrode, a titanium aluminum electrode, a nickel-gold electrode, a chromium-gold electrode, a copper-gold electrode, a titanium-gold electrode, a platinum electrode or a palladium electrode, and the thickness of the first electrode is 1-500 nm;
the second electrode is arranged as a platinum electrode or a palladium electrode or a platinum alloy or a palladium alloy, and the thickness of the second electrode is 1-1000 nm.
4. The capacitive hydrogen sensor core of claim 1, wherein said pre-treating said dielectric sheet and oxidizing said pre-treated dielectric sheet at an end thereof facing away from said substrate to obtain a group iii oxide layer, comprising:
ultrasonically cleaning a medium sheet made of III-group nitride material growing on a substrate for 5 min sequentially through acetone, absolute ethyl alcohol and deionized water, and blow-drying the medium sheet by a nitrogen gun;
placing the medium sheet into a high temperature furnace, charging oxygen into the high temperature furnace, and maintaining the pressure to 1.01X10 5 Pa, heating the dielectric layer to 500-800 ℃ and preserving heat for 5-100 min, and controlling the temperature rising speed and the temperature reducing speed to 10 ℃ per min to obtain a III-group oxide layer; or, putting the dielectric sheet into sulfuric acid or hydrogen peroxide, and soaking for 3-30 min to obtain a III-group oxide layer; or, the dielectric sheet is placed into an oxygen plasma instrument, the power of the oxygen plasma instrument is controlled to be 10-500W, the internal air pressure is 1-50 Pa, and the treatment time is 1-100 min, so that the III-group oxide layer is obtained.
5. A capacitive hydrogen sensor, comprising: a capacitive hydrogen sensor core as claimed in any one of claims 1 to 4.
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| CN103558253A (en) * | 2013-11-11 | 2014-02-05 | 中国石油大学(华东) | Palladium/titanium dioxide/silicon dioxide/silicon heterojunction-based hydrogen detector |
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| Title |
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| I-Ping Liu et al..Study of a GaN Schottky diode based hydrogen sensor with a hydrogen peroxide oxidation approach and platinum catalytic metal.INTERNATIONAL JOURNAL OF HYDROGEN ENERGY.2019,第44卷第32351-32361页. * |
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