CN111141790A - Method for regulating and controlling detection concentration range and sensitivity of hydrogen detector - Google Patents
Method for regulating and controlling detection concentration range and sensitivity of hydrogen detector Download PDFInfo
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Abstract
The invention relates to the technical field of gas detectors, and provides a method for regulating and controlling the detection concentration range and sensitivity of a hydrogen detector, wherein in the preparation process of the hydrogen detector, the detection concentration range and sensitivity of the hydrogen detector are regulated and controlled by changing the annealing atmosphere of an oxide semiconductor film; the annealing atmosphere comprises oxygen, air, vacuum or hydrogen. The invention gives full play to the advantages of the traditional metal oxide gas-sensitive material, and utilizes different atmospheres to carry out annealing treatment on the oxide semiconductor film to obtain films with different surface roughness degrees and oxygen vacancy concentrations, thereby realizing the regulation and control of the detection concentration range and sensitivity of the hydrogen detector, obtaining hydrogen detectors with different detection concentration ranges and different sensitivities, and further meeting the requirements of different occasions on the hydrogen sensor.
Description
Technical Field
The invention relates to the technical field of gas sensors, in particular to a method for regulating and controlling the detection concentration range and sensitivity of a hydrogen detector.
Background
Hydrogen, as a renewable green energy source, has a high energy density and is widely used in the fields of chemical raw materials, metallurgy and many other related basic raw materials. However, hydrogen is a flammable and explosive gas, and presents an almost invisible blue flame when ignited, and is very easy to explode when the volume concentration in the air reaches 4-75%. For safe use, real-time detection of hydrogen leakage is the most important basis for full utilization of hydrogen energy.
Hydrogen sensing can be largely classified into optical, electrochemical, and chemical sensors based on the response mechanism. Titanium dioxide is a wide-bandgap n-type semiconductor material, has unique optical, electrical, catalytic and gas sensing characteristics, has the characteristics of low cost and stability under a high-severe environment, and is considered as one of the most potential candidate materials of the future intelligent hydrogen sensor. Based on a detection mechanism of titanium dioxide, a severe high-temperature environment (200-300 ℃) is required in the adsorption and desorption processes of hydrogen, and the adsorption activation energy of the hydrogen on the surface of the sensor is reduced through the high-temperature environment, so that the sensitivity of a device is improved, and the low-concentration detection limit is reached; and fast desorption energy can be obtained in a short time at high temperature so as to expand the detection range of the detector for hydrogen at high concentration, but the high-temperature environment increases the energy consumption cost and potential safety hazard. The relevant literature reports that the detection limit of low concentration of titanium dioxide film at room temperature can reach 30ppm and the detectable limit concentration at room temperature is only 300ppm due to lower sensitivity.
At present, the detection limit of hydrogen at room temperature is as low as 1ppm, the sensitivity is 4%, and the concentration detection range is 1-2000 ppm by using a rutile titanium dioxide film hydrogen sensor. However, the requirements for hydrogen detectors in different application occasions are different, and in some occasions, a hydrogen sensor is required to have a wider detection concentration range, and in some occasions, the hydrogen sensor is required to have higher sensitivity and have lower requirements for the detection range. However, no effective method for regulating and controlling the detection concentration and sensitivity of the hydrogen sensor at room temperature exists at present.
Disclosure of Invention
In view of this, the present invention aims to provide a method for regulating and controlling the detection concentration range and sensitivity of a hydrogen detector. The method provided by the invention can effectively regulate and control the concentration detection range and sensitivity of the hydrogen detector, and the detector suitable for different occasions is obtained.
In order to achieve the above object, the present invention provides the following technical solutions:
a method for regulating and controlling the detection concentration range and sensitivity of a hydrogen detector is characterized in that in the preparation process of the hydrogen detector, the detection concentration range and sensitivity of the hydrogen detector are regulated and controlled by changing the annealing atmosphere of an oxide semiconductor film; the annealing atmosphere comprises oxygen, air, vacuum or hydrogen.
Preferably, the oxide semiconductor thin film includes, but is not limited to, a titanium dioxide thin film, a tin dioxide thin film, a zinc oxide thin film, a tungsten oxide thin film, or a nickel oxide thin film.
Preferably, the preparation process of the hydrogen detector comprises the following steps:
(1) preparing a seed crystal layer on the surface of the substrate by using a magnetron sputtering method, and then annealing in an air atmosphere;
(2) preparing an oxide semiconductor film on the surface of the annealed seed crystal layer by using a hydrothermal method, and then annealing the oxide semiconductor film; the annealing atmosphere comprises oxygen, air, vacuum or hydrogen;
(3) and preparing an interdigital electrode on the surface of the annealed oxide semiconductor film by using a magnetron sputtering method to obtain the hydrogen detector.
Preferably, the temperature for annealing the oxide semiconductor film is 200-600 ℃ and the time is 20-120 min.
Preferably, the regulation range of the detection concentration range of the hydrogen detector is 50 ppb-2%, and the regulation range of the sensitivity under the hydrogen concentration of 1ppm is 1% -80%.
Preferably, when the annealing atmosphere of the oxide semiconductor thin film is oxygen, the detection concentration of the obtained hydrogen detector is 1ppm to 4000ppm or 1ppm to 20000ppm, and the sensitivity at 1ppm hydrogen concentration is 1 to 5%.
Preferably, when the annealing atmosphere of the oxide semiconductor thin film is air, the detection concentration of the obtained hydrogen detector is 1ppm to 2000ppm, and the sensitivity is 3 to 10% at a hydrogen concentration of 1 ppm.
Preferably, when the annealing atmosphere of the oxide semiconductor thin film is vacuum, the detection concentration of the obtained hydrogen detector is 1ppm to 800ppm, and the sensitivity under the hydrogen concentration of 1ppm is 20 to 40%.
Preferably, when the annealing atmosphere of the oxide semiconductor thin film is hydrogen, the detection concentration of the obtained hydrogen detector is 1ppm to 400ppm or 53ppb to 800ppm, and the sensitivity at 1ppm hydrogen concentration is 30 to 70%.
The invention provides a method for regulating and controlling the detection concentration range and sensitivity of a hydrogen detector, wherein in the preparation process of the hydrogen detector, the detection concentration range and sensitivity of the hydrogen detector are regulated and controlled by changing the annealing atmosphere of an oxide semiconductor film; the annealing atmosphere comprises oxygen, air, vacuum or hydrogen. Wherein, the hydrogen detector annealed by oxygen and air atmosphere (oxidation annealing) has wider hydrogen concentration detection range and good stability at room temperature; the hydrogen detection sensitivity of the hydrogen detector obtained by vacuum and hydrogen atmosphere annealing (reduction annealing) at room temperature is obviously improved, and the detection limit is further expanded to low concentration. The invention gives full play to the advantages of the traditional metal oxide gas-sensitive material, and utilizes different atmospheres to carry out annealing treatment on the oxide semiconductor film to obtain films with different surface roughness degrees and oxygen vacancy concentrations, thereby realizing the regulation and control of the detection concentration range and sensitivity of the hydrogen detector, obtaining hydrogen detectors with different detection concentration ranges and different sensitivities, and further meeting the requirements of different occasions on the hydrogen sensor; the method provided by the invention has the advantages of low cost, high reliability, high repetition rate and higher device stability, and can be widely applied to the field of oxide film gas detectors. The embodiment result shows that the method can realize that the detection concentration range of the hydrogen detector is controllable within 50 ppb-2%, and the sensitivity is controllable within 1% -80% under the hydrogen concentration of 1 ppm.
Drawings
FIG. 1 AFM image of a titanium dioxide film after oxygen annealing in example 1;
FIG. 2 is a response curve of the titanium dioxide thin film hydrogen detector prepared in example 1 to different concentrations of hydrogen at room temperature;
FIG. 3 is a resistance change curve of the titanium dioxide thin film hydrogen sensor prepared in example 1;
FIG. 4 is a resistance change curve of the titanium dioxide thin film hydrogen sensor manufactured in example 2;
FIG. 5 AFM image of titania film after air annealing in example 3;
FIG. 6 is a response curve of the titanium dioxide thin film hydrogen detector prepared in example 3 to different concentrations of hydrogen at room temperature;
FIG. 7 is a resistance change curve of the titanium dioxide thin film hydrogen sensor prepared in example 3;
FIG. 8 AFM image of a titanium dioxide film after vacuum annealing in example 4;
FIG. 9 is a graph showing the response of the titanium dioxide thin film hydrogen detector prepared in example 4 to different concentrations of hydrogen at room temperature;
FIG. 10 is a resistance change curve of the titanium dioxide thin film hydrogen sensor manufactured in example 4;
FIG. 11 AFM image of a titanium dioxide film after hydrogen annealing in example 5;
FIG. 12 is a graph showing the response of the titanium dioxide thin film hydrogen sensor prepared in example 5 to different concentrations of hydrogen at room temperature;
FIG. 13 is a resistance change curve of the titanium dioxide thin film hydrogen sensor manufactured in example 5;
FIG. 14 is a resistance change curve of the titanium dioxide thin film hydrogen sensor manufactured in example 6;
FIG. 15 is an X-ray diffraction pattern of the titanium dioxide thin films annealed without different atmospheres in examples 1, 3 and 5.
Detailed Description
The invention provides a method for regulating and controlling the detection concentration range and sensitivity of a hydrogen detector, wherein in the preparation process of the hydrogen detector, the detection concentration range and sensitivity of the hydrogen detector are regulated and controlled by changing the annealing atmosphere of an oxide semiconductor film; the annealing atmosphere comprises oxygen, air, vacuum or hydrogen.
In the present invention, the oxide semiconductor thin film is preferably a titanium dioxide thin film, a tin dioxide thin film, a zinc oxide thin film, a tungsten oxide thin film, or a nickel oxide thin film, and more preferably a titanium dioxide thin film.
In the present invention, the preparation process of the hydrogen detector preferably includes the steps of:
(1) preparing a seed crystal layer on the surface of the substrate by using a magnetron sputtering method, and then annealing in an air atmosphere;
(2) preparing an oxide semiconductor film on the surface of the annealed seed crystal layer by using a hydrothermal method, and then annealing the oxide semiconductor film; the annealing atmosphere comprises oxygen, air, vacuum or hydrogen;
(3) and preparing an interdigital electrode on the surface of the annealed oxide semiconductor film by using a magnetron sputtering method to obtain the hydrogen detector.
The method prepares the seed crystal layer on the surface of the substrate by utilizing a magnetron sputtering method, and then anneals in the air atmosphere. In the present invention, the substrate is preferably an FTO substrate; before the magnetron sputtering, the substrate is preferably washed and dried in sequence; the washing is preferably ultrasonic cleaning in acetone, ethanol and deionized water for 20min in sequence. In the present invention, the degree of vacuum of the back surface is preferably 6X 10 when the seed layer is sputtered by the magnetron sputtering method-6Pa, the sputtering pressure is preferably 1Pa, the radio frequency power is preferably 120W, the Ar flow rate is preferably 36sccm, and O2The flow rate is preferably 1sccm, and the sputtering time is preferably 15 min; the thickness of the seed crystal layer is preferably 500n, and the target material for sputtering the seed crystal layer is preferably selected according to the type of the oxide semiconductor thin film; in the invention, the annealing temperature of the seed crystal layer in the air atmosphere is preferably 500 ℃, and the holding time is preferably 10 min.
After the seed crystal layer is annealed, the oxide semiconductor film is prepared on the surface of the annealed seed crystal layer by using a hydrothermal method. In the present invention, the hydrothermal method is preferably: placing the precursor solution in a hydrothermal reaction kettle, enabling the conductive surfaces of two FTO substrates containing seed crystal layers to face downwards and lean against the inner wall of the reaction kettle in a V shape, enabling the seed crystal layers to be in contact with the precursor solution, carrying out hydrothermal reaction, and obtaining an oxide semiconductor film on the surface of the seed crystal layers; the temperature of the hydrothermal reaction is preferably 150 ℃, and the reaction time is preferably 8 h; when the oxide semiconductor film is a titanium dioxide film, the precursor solution is preferably prepared from water, absolute ethyl alcohol, concentrated hydrochloric acid and tetrabutyl titanate; the volume ratio of the water to the absolute ethyl alcohol to the concentrated hydrochloric acid to the tetrabutyl titanate is preferably 15:15:30: 1; the precursor solution preparation method for preparing the tin dioxide film, the zinc oxide film, the tungsten oxide film or the nickel oxide film has no special requirements and can be prepared according to the method well known by the technical personnel in the field. According to the invention, a substrate containing a seed crystal layer is subjected to hydrothermal reaction in a precursor solution, a layer of nanorod can grow on the surface of the seed crystal layer, namely the oxide semiconductor film, the diameter of the nanorod is preferably 90-105 nanometers, and the length of the nanorod is preferably 2-3 micrometers.
In the present invention, after the hydrothermal reaction is completed, the obtained oxide semiconductor film is preferably cleaned, and specifically, the substrate on which the oxide semiconductor film is grown is preferably soaked in deionized water for 6 hours, water is changed every 3 hours, and then the substrate is dried at a constant temperature of 70 ℃.
After the oxide semiconductor film is prepared, annealing the oxide semiconductor film; the annealing atmosphere comprises oxygen, air, vacuum or hydrogen; the annealing temperature is preferably 200-600 ℃, more preferably 400 ℃, and the time is preferably 20-120 min, more preferably 30-90 min; when the annealing atmosphere is oxygen, air or vacuum, the annealing is preferably performed in a tube furnace; when the annealing atmosphere is hydrogen, the annealing is preferably carried out in a plasma enhanced chemical vapor deposition device (PECVD device), and the invention preferably has the background vacuum degree of 6 x 10-4Introducing hydrogen when Pa, wherein the flow rate of the hydrogen is preferably 40 sccm; when the annealing atmosphere is a vacuum atmosphere, the degree of vacuum of the annealing is preferably 6 × 10-4Pa。
The invention can obtain films with different surface roughness degrees and oxygen vacancy concentrations by changing the annealing atmosphere of the oxide semiconductor film, thereby realizing the regulation and control of the detection concentration range and sensitivity of the hydrogen detector. Wherein, the hydrogen detector annealed by oxygen and air atmosphere (oxidation annealing) has wider hydrogen concentration detection range and good stability at room temperature; the hydrogen detection sensitivity of the hydrogen detector obtained by vacuum and hydrogen atmosphere annealing (reduction annealing) at room temperature is obviously improved, and the detection limit is further expanded to low concentration.
In the invention, the regulation range of the detection concentration range of the hydrogen detector is preferably 50 ppb-2%, and the regulation range of the sensitivity under the hydrogen concentration of 1ppm is preferably 1% -80%. In the present invention, the sensitivity is calculated by the following formula: the sensitivity is Ra-Rg/Ra 100%, wherein Ra is the resistance value of the detector exposed to the air, and Rg is the resistance value of the detector exposed to the hydrogen atmosphere.
In the embodiment of the invention, when the annealing atmosphere of the oxide semiconductor film is preferably oxygen, the detection concentration of the obtained hydrogen detector is 1ppm to 4000ppm or 1ppm to 20000ppm, and the sensitivity under the hydrogen concentration of 1ppm is 1 to 5 percent, preferably 3 percent; when the annealing atmosphere of the oxide semiconductor film is preferably air, the detection concentration of the obtained hydrogen detector is 1 ppm-2000 ppm, and the sensitivity under the hydrogen concentration of 1ppm is 3-10%, preferably 4%; when the annealing atmosphere of the oxide semiconductor film is preferably vacuum, the detection concentration of the obtained hydrogen detector is 1 ppm-800 ppm, and the sensitivity under the hydrogen concentration of 1ppm is 20-40%, preferably 38%; when the annealing atmosphere of the oxide semiconductor film is preferably hydrogen, the detection concentration of the obtained hydrogen detector is 1ppm to 400ppm or 53ppb to 800ppm, and the sensitivity at the hydrogen concentration of 1ppm is 30 to 70%, preferably 35.5%.
After the oxide semiconductor film is annealed, the invention prepares the interdigital electrode on the surface of the annealed oxide semiconductor film by using a magnetron sputtering method to obtain the hydrogen detector. In the invention, the interdigital electrode is preferably a platinum interdigital electrode, and the thickness of the interdigital electrode is preferably 800-900 nm; the direct current sputtering power of the magnetron sputtering is preferably 40W, the Ar flow rate is preferably 14.4sccm, the working gas pressure is preferably 0.5Pa, the sputtering time is preferably 5min,the degree of vacuum of the back substrate before sputtering is preferably 6X 10-4Pa。
The embodiments of the present invention will be described in detail with reference to the following examples, but they should not be construed as limiting the scope of the present invention.
Example 1
And ultrasonically cleaning the FTO substrate in acetone, absolute ethyl alcohol and deionized water for 20min, drying and fixing the FTO substrate on a magnetron sputtering tray. TiO with the purity of 99.99 percent2The target material is arranged at the cathode target position of the magnetron sputtering system, and the distance between the target material and the substrate is adjusted to be 60 mm. When the vacuum degree in the sputtering cavity reaches 6 multiplied by 10-4When Pa is needed, the flow rates of argon and oxygen are respectively set to be 36sccm and 1sccm, the air pressure in the sputtering cavity is kept to be 1Pa, the radio frequency sputtering power is set to be 120W, the target material is pre-sputtered for 10min, then the radio frequency power is kept to be 120W, deposition is continuously carried out on the FTO substrate for 15min, and a layer of TiO is obtained by deposition on the FTO substrate2And taking the seed crystal layer out of the vacuum chamber, and performing rapid annealing at 500 ℃ for 10min in an air atmosphere.
Leaning the annealed sample on the inner wall of polytetrafluoroethylene of a hydrothermal reaction kettle in a V shape, pouring a precursor solution prepared from 15mL of deionized water, 15mL of absolute ethyl alcohol, 30mL of concentrated hydrochloric acid and 1mL of tetrabutyl titanate, and carrying out hydrothermal reaction for 8h at 150 ℃ to obtain TiO2Cooling the film with the reaction kettle to room temperature, washing the film with deionized water, soaking the film in the deionized water, changing water every 3 hours, soaking for 6 hours, drying at a constant temperature of 70 ℃, and annealing at 400 ℃ for 20min in an oxygen atmosphere of a tube furnace for later use.
The Pt target material with the purity of 99.99 percent is arranged at the cathode target position of a magnetron sputtering system, the distance between a fixed target and a substrate is 60mm, and the Pt target material is arranged on TiO2Covering interdigital mask plates on the surface of the film, respectively opening a mechanical pump and a solenoid valve molecular pump pumping system, and pumping to a background vacuum degree of 6 multiplied by 10-4And when Pa is needed, setting the flow rate of argon gas to be 14.4sccm, keeping the working pressure of the chamber to be 0.5Pa, setting the direct-current sputtering power to be 40w, and carrying out 5-min sputtering coating on the target to prepare the metal Pt electrode.
FIG. 1 is an AFM image of a titanium dioxide film after oxygen annealing; it is understood from the graph that the root mean square roughness of the titanium dioxide thin film after oxygen annealing was 14.529 nm.
And detecting the obtained titanium dioxide film hydrogen detector at room temperature, wherein the obtained result is shown in fig. 2-3, wherein fig. 2 is a response curve of the titanium dioxide film hydrogen detector under different hydrogen concentrations, and fig. 3 is a resistance value change curve of the titanium dioxide film hydrogen detector. As can be seen from FIGS. 2 to 3, the detection concentration limit of the obtained hydrogen detector can reach 1ppm, and the sensitivity is 3%; the sensitivity of 10ppm is 5%, the sensitivity of 100ppm is 9%, and the detection range is 1 ppm-4000 ppm.
Example 2
Otherwise, only TiO was controlled as in example 12The annealing temperature of the film is 350 ℃ and the time is 20 min.
Detecting the obtained titanium dioxide film hydrogen detector at room temperature, wherein the resistance change curve of the obtained titanium dioxide film hydrogen detector under different hydrogen concentrations is shown in figure 4, and as can be seen from figure 4, the detection concentration limit of the obtained hydrogen detector can reach 1ppm, and the sensitivity is 4%; the sensitivity of 10ppm is 7 percent, the sensitivity of 100ppm is 15 percent, and the detection range is 1ppm to 20000 ppm.
Example 3
And ultrasonically cleaning the FTO substrate in acetone, absolute ethyl alcohol and deionized water for 20min, drying and fixing the FTO substrate on a magnetron sputtering tray. TiO with the purity of 99.99 percent2The target material is arranged at the cathode target position of the magnetron sputtering system, and the distance between the target material and the substrate is adjusted to be 60 mm. When the vacuum degree in the sputtering cavity reaches 10-4When the order of Pa is in an order of magnitude, the flow rates of argon and oxygen are respectively set to be 36sccm and 1sccm, the air pressure in a sputtering cavity is kept to be 1Pa, the radio frequency sputtering power is set to be 120W, the target is subjected to pre-sputtering for 10min, then the radio frequency power is kept to be 120W, a layer of TiO is obtained by deposition on the FTO substrate in a continuous deposition process for 15min2And taking the seed crystal layer out of the vacuum chamber, and performing rapid annealing at 500 ℃ for 10min in an air atmosphere. Putting the annealed sample against the inner wall of polytetrafluoroethylene in a hydrothermal reaction kettle in a V shape, and pouring 15mL of deionized water, 15mL of absolute ethyl alcohol and 30mL of concentrated solutionHydrochloric acid and 1mL tetrabutyl titanate are prepared into precursor solution, and the precursor solution is subjected to hydrothermal reaction for 8 hours at the temperature of 150 ℃ to obtain TiO2The film is cleaned by deionized water, soaked in the deionized water, water is changed every 3 hours for 6 hours, and after drying at the constant temperature of 70 ℃, the film is annealed for 20min at the temperature of 400 ℃ in the air atmosphere of a tubular furnace for later use.
The Pt target material with the purity of 99.99 percent is arranged at the cathode target position of a magnetron sputtering system, the distance between a fixed target and a substrate is 60mm, and the Pt target material is arranged on TiO2Covering interdigital mask plates on the surface of the film, respectively opening a mechanical pump and a solenoid valve molecular pump pumping system, and pumping to a background vacuum degree of 6 multiplied by 10-4And when Pa is needed, setting the flow rate of argon gas to be 14.4sccm, keeping the air pressure of the chamber to be 0.5Pa, setting the direct-current sputtering power to be 40w, and carrying out 5-min sputtering coating on the target to prepare the metal Pt electrode.
FIG. 5 is an AFM image of a titanium dioxide film after air annealing; it is understood from the graph that the root mean square roughness of the titanium dioxide thin film after air annealing was 18.690 nm.
Detecting the obtained titanium dioxide film hydrogen detector at room temperature, wherein the obtained result is shown in fig. 5-6, fig. 6 is a response curve of the titanium dioxide film hydrogen detector under different hydrogen concentrations, and fig. 7 is a resistance value change curve of the titanium dioxide film hydrogen detector; as can be seen from FIGS. 6 to 7, the detection concentration limit of the obtained hydrogen detector can reach 1ppm, and the sensitivity is 4%; 10ppm sensitivity of 7%; the sensitivity of 100ppm is 15%, and the detection range is 1 ppm-2000 ppm.
Example 4
And ultrasonically cleaning the FTO substrate in acetone, absolute ethyl alcohol and deionized water for 20min, drying and fixing the FTO substrate on a magnetron sputtering tray. TiO with the purity of 99.99 percent2The target material is arranged at the cathode target position of the magnetron sputtering system, and the distance between the target material and the substrate is adjusted to be 60 mm. When the vacuum degree in the sputtering cavity reaches 6 multiplied by 10-4When Pa is needed, the flow rates of argon and oxygen are respectively set to be 36sccm and 1sccm, the air pressure in the sputtering cavity is kept to be 1Pa, the radio frequency sputtering power is set to be 120W, the target is subjected to pre-sputtering for 10min, then the radio frequency power is kept to be 120W, deposition is continuously carried out on the FTO substrate for 15min, and then the FTO is carried out on the FTO substrateDepositing on the substrate to obtain a layer of TiO2And taking the seed crystal layer out of the vacuum chamber, and performing rapid annealing at 500 ℃ for 10min in an air atmosphere.
Leaning the annealed sample on the inner wall of polytetrafluoroethylene of a hydrothermal reaction kettle in a V shape, pouring a precursor solution prepared from 15mL of deionized water, 15mL of absolute ethyl alcohol, 30mL of concentrated hydrochloric acid and 1mL of tetrabutyl titanate, and carrying out hydrothermal reaction for 8h at 150 ℃ to obtain TiO2And when the reaction kettle is cooled to room temperature, cleaning the film with deionized water, soaking the film in the deionized water, changing water every 3 hours for 6 hours, and drying the film at the constant temperature of 70 ℃ for later use. The vacuum degree of the bottom of the tube furnace reaches 6 multiplied by 10 by a pumping system-4Pa, annealing at 400 ℃ for 20min in vacuum atmosphere for later use.
The Pt target material with the purity of 99.99 percent is arranged at the cathode target position of a magnetron sputtering system, the distance between a fixed target and a substrate is 60mm, and the Pt target material is arranged on TiO2Covering interdigital mask plate on the surface of film, respectively opening mechanical pump and electromagnetic valve molecular pump pumping system, and pumping to 6X 10 to obtain film with background vacuum-4And when Pa is needed, setting the flow rate of argon gas to be 14.4sccm, keeping the air pressure of the chamber to be 0.5Pa, setting the direct-current sputtering power to be 40w, and carrying out 5-min sputtering coating on the target to prepare the metal Pt electrode.
FIG. 8 is an AFM image of a titanium dioxide film after vacuum annealing; it is understood from the graph that the root mean square roughness of the titanium dioxide thin film after vacuum annealing is 20.577 nm.
Detecting the obtained titanium dioxide film hydrogen detector at room temperature, wherein the obtained result is shown in fig. 9-10, fig. 9 is a response curve of the titanium dioxide film hydrogen detector under different hydrogen concentrations, and fig. 10 is a resistance value change curve of the titanium dioxide film hydrogen detector; according to the graphs of 9-10, the detection concentration limit of the obtained hydrogen detector is lower than 1ppm, and the sensitivity is 38%; sensitivity at 10ppm of 53%; the sensitivity of 100ppm is 90 percent, and the detection range is 1ppm to 800 ppm.
Example 5
And ultrasonically cleaning the FTO substrate in acetone, absolute ethyl alcohol and deionized water for 20min, drying and fixing the FTO substrate on a magnetron sputtering tray. Mixing Ti with the purity of 99.99 percentO2The target material is arranged at the cathode target position of the magnetron sputtering system, and the distance between the target material and the substrate is adjusted to be 60 mm. When the vacuum degree in the sputtering cavity reaches 6 multiplied by 10-4When Pa is needed, the flow rates of argon and oxygen are respectively set to be 36sccm and 1sccm, the air pressure in the sputtering cavity is kept to be 1Pa, the radio frequency sputtering power is set to be 120w, the target material is pre-sputtered for 10min, then the radio frequency power is kept to be 120w, deposition is continuously carried out on the FTO substrate for 15min, and a layer of TiO is obtained by deposition on the FTO substrate2And taking the seed crystal layer out of the vacuum chamber, and performing rapid annealing at 500 ℃ for 10min in an air atmosphere.
Leaning the annealed sample on the inner wall of polytetrafluoroethylene of a hydrothermal reaction kettle in a V shape, pouring a precursor solution prepared from 15mL of deionized water, 15mL of absolute ethyl alcohol, 30mL of concentrated hydrochloric acid and 1mL of tetrabutyl titanate, and carrying out hydrothermal reaction for 8h at 150 ℃ to obtain TiO2After the reaction kettle is cooled to room temperature, the film is washed by deionized water and soaked in the deionized water, water is changed every 3 hours, the film is soaked for 6 hours, and the film is dried at the constant temperature of 70 ℃ for later use. Using PECVD pumping system until the background vacuum degree reaches 6X 10-4And when Pa is needed, introducing hydrogen into the chamber at the hydrogen flow rate of 40sccm, and annealing at 400 ℃ for 20min in a hydrogen atmosphere for later use.
The Pt target material with the purity of 99.99 percent is arranged at the cathode target position of a magnetron sputtering system, the distance between a fixed target and a substrate is 60mm, and the Pt target material is arranged on TiO2Covering interdigital mask plates on the surface of the film, respectively opening a mechanical pump and a solenoid valve molecular pump pumping system, and pumping to a background vacuum degree of 6 multiplied by 10-4And when Pa is needed, setting the flow rate of argon gas to be 14.4sccm, keeping the air pressure of the chamber to be 0.5Pa, setting the direct-current sputtering power to be 40w, and carrying out 5-min sputtering coating on the target to prepare the metal Pt electrode.
FIG. 11 is an AFM image of a titanium dioxide film after hydrogen annealing; it is understood from the graph that the root mean square roughness of the titanium dioxide thin film after hydrogen annealing was 24.098 nm.
Detecting the obtained titanium dioxide film hydrogen detector at room temperature, wherein the obtained result is shown in fig. 12-13, fig. 12 is a response curve of the titanium dioxide film hydrogen detector under different hydrogen concentrations, and fig. 13 is a resistance value change curve of the titanium dioxide film hydrogen detector; as can be seen from FIGS. 12 to 13, the limit of the detection concentration of the obtained hydrogen detector can reach 1ppm, the sensitivity is 35.5%, the sensitivity is 60% at 10ppm, the sensitivity is 92% at 100ppm, and the detection range is 1ppm to 400 ppm.
Example 6
Other conditions were the same as in example 5 except that TiO alone was controlled2The annealing temperature of the film is 500 ℃ and the time is 20 min.
The obtained titanium dioxide film hydrogen detector is detected at room temperature, the resistance value change curve of the obtained titanium dioxide film hydrogen detector under different hydrogen concentrations is shown in figure 14, and as can be seen from figure 14, the detection concentration limit of the obtained hydrogen detector can reach 53ppb, and the sensitivity is 26%; the sensitivity of 10ppm is 78%, the sensitivity of 100ppm is 87%, and the detection range is 53 ppb-800 ppm.
FIG. 15 is an X-ray diffraction pattern of titanium dioxide films annealed without different atmospheres in examples 1, 3-5, wherein TAO represents oxygen annealing, TAA represents air annealing, TAV represents vacuum annealing, and TAH represents hydrogen annealing; as can be seen from FIG. 15, the grain size of the prepared titanium dioxide film is nano-scale, and the growth orientation of the titanium dioxide film is not changed by annealing in different atmospheres.
The embodiment shows that the method provided by the invention can effectively change the roughness of the surface of the film and the concentration of oxygen vacancies by changing the annealing atmosphere of the oxide semiconductor film, thereby regulating and controlling the detection range and sensitivity of the hydrogen detector and obtaining the hydrogen detector suitable for different occasions.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.
Claims (9)
1. A method for regulating and controlling the detection concentration range and sensitivity of a hydrogen detector is characterized in that in the preparation process of the hydrogen detector, the detection concentration range and sensitivity of the hydrogen detector are regulated and controlled by changing the annealing atmosphere of an oxide semiconductor film; the annealing atmosphere comprises oxygen, air, vacuum or hydrogen.
2. The conditioning method according to claim 1, wherein the oxide semiconductor thin film comprises but is not limited to a titanium dioxide thin film, a tin dioxide thin film, a zinc oxide thin film, a tungsten oxide thin film, or a nickel oxide thin film.
3. A regulation and control method according to claim 1, characterized in that the hydrogen detector is produced by a process comprising the following steps:
(1) preparing a seed crystal layer on the surface of the substrate by using a magnetron sputtering method, and then annealing in an air atmosphere;
(2) preparing an oxide semiconductor film on the surface of the annealed seed crystal layer by using a hydrothermal method, and then annealing the oxide semiconductor film; the annealing atmosphere comprises oxygen, air, vacuum or hydrogen;
(3) and preparing an interdigital electrode on the surface of the annealed oxide semiconductor film by using a magnetron sputtering method to obtain the hydrogen detector.
4. The method according to claim 3, wherein the annealing of the oxide semiconductor film is performed at a temperature of 200 to 600 ℃ for 20 to 120 min.
5. The control method according to claim 1 or 3, wherein the control range of the detection concentration range of the hydrogen detector is 50ppb to 2%, and the control range of the sensitivity at a hydrogen concentration of 1ppm is 1% to 80%.
6. A control method according to claim 5, wherein when the annealing atmosphere of the oxide semiconductor thin film is oxygen, the detection concentration of the obtained hydrogen detector is 1ppm to 4000ppm or 1ppm to 20000ppm, and the sensitivity at a hydrogen concentration of 1ppm is 1 to 5%.
7. A control method according to claim 5, wherein when the annealing atmosphere of the oxide semiconductor thin film is air, the detection concentration of the obtained hydrogen detector is 1ppm to 2000ppm, and the sensitivity at a hydrogen concentration of 1ppm is 3 to 10%.
8. A control method according to claim 5, wherein when an annealing atmosphere of the oxide semiconductor thin film is vacuum, a detection concentration of the obtained hydrogen detector is 1ppm to 800ppm, and a sensitivity at a hydrogen concentration of 1ppm is 20 to 40%.
9. The control method according to claim 5, wherein when the annealing atmosphere of the oxide semiconductor thin film is hydrogen, the detection concentration of the obtained hydrogen detector is 1ppm to 400ppm or 53ppb to 800ppm, and the sensitivity at a hydrogen concentration of 1ppm is 30 to 70%.
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| CN104569077A (en) * | 2015-01-26 | 2015-04-29 | 湖北大学 | Titanium dioxide film hydrogen sensor and preparation method thereof |
| CN109298030A (en) * | 2018-11-22 | 2019-02-01 | 湖北大学 | A kind of niobium doped anatase phase titanic oxide film gas sensor and preparation method thereof |
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| CN104569077A (en) * | 2015-01-26 | 2015-04-29 | 湖北大学 | Titanium dioxide film hydrogen sensor and preparation method thereof |
| CN109298030A (en) * | 2018-11-22 | 2019-02-01 | 湖北大学 | A kind of niobium doped anatase phase titanic oxide film gas sensor and preparation method thereof |
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