JP4355300B2 - Hydrogen permeable membrane, hydrogen sensor, and hydrogen detection method - Google Patents

Description

  The present invention provides a hydrogen permeable membrane that selectively permeates hydrogen, and a hydrogen sensor that can easily detect hydrogen at room temperature and can detect only hydrogen without being affected by the presence of flammable gas such as methane gas. And a hydrogen detection method.

  Conventionally, a hydrogen sensor has been proposed in which a thin film that suppresses the passage of a gas other than hydrogen and selectively allows hydrogen to pass therethrough as a protective film on the surface of a gas sensor made of a metal oxide semiconductor. As a thin film of this hydrogen sensor, for example, a thin film of alumina, silica, silicon nitride or the like is generally used. This type of hydrogen sensor protects the sensing element by forming a dense and uniform continuous thin film (hydrogen-selective permeable membrane) on the surface of the gas sensing element, and reduces interference from gases other than hydrogen. The aim is to realize a hydrogen sensor with high sensitivity and hydrogen selectivity.

For example, Patent Document 1 below discloses a hydrogen sensor having a semiconductor layer made of strontium titanate on a support substrate made of alumina and an outer layer made of silicon dioxide or silicon nitride covering the semiconductor layer. . In this hydrogen sensor, it is described that since the outer layer made of silicon dioxide or silicon nitride selectively allows hydrogen to pass therethrough, it can be suitably used as a hydrogen permeable membrane for a hydrogen sensor.
JP-T-2002-513930

  By the way, in the hydrogen sensor described in Patent Document 1, hydrogen is detected by the sensitive body after passing through the hydrogen-selective permeable membrane formed on the surface of the sensitive body. Since there is some resistance to the flow, it is inevitable that the response speed tends to be slower than a hydrogen sensor that does not use a hydrogen-selective permeable membrane.

This invention is made | formed in view of the said situation, Comprising: It aims at providing the hydrogen permeable film which can suppress the fall of a response speed, fulfill | performing a function as a protective film.
It is another object of the present invention to provide a hydrogen sensor and a hydrogen detection method having a high response speed by applying the hydrogen permeable membrane to a hydrogen sensor.
In addition, hydrogen can be selectively permeated and can be detected at room temperature, and since there is no need for heating, it can be made into a power saving structure and can be used repeatedly even once hydrogen detection is completed. An object of the present invention is to provide a hydrogen sensor and a hydrogen detection method that can be used for a long period of time.

In order to achieve the above object, the present invention employs the following configuration.
The hydrogen permeable membrane of the present invention is characterized by being made of silicon oxide to which phosphorus is added. According to such a configuration, resistance when hydrogen permeates through the hydrogen permeable membrane is small, and a decrease in response speed can be suppressed.
The hydrogen permeable membrane of the present invention is characterized in that the amount of phosphorus added is in the range of 0.1 to 1.0 wt%. According to this configuration, the same effect as described above can be obtained.

  The hydrogen sensor of the present invention includes a semiconductor, a hydrogen absorber attached to at least a part of the surface of the semiconductor, a hydrogen permeable film that covers an exposed surface of the hydrogen absorber and transmits hydrogen, and the hydrogen absorber. The semiconductor is provided with a pair of electrodes arranged so as not to be conducted by the hydrogen absorber, and the hydrogen permeable film is made of silicon oxide to which phosphorus is added, and the hydrogen absorber The presence of hydrogen can be detected by measuring a change in resistance value of the semiconductor corresponding to the presence or absence of hydrogen absorption between the pair of electrodes.

According to such a configuration, resistance when hydrogen permeates through the hydrogen permeable membrane is small, and a decrease in response speed can be suppressed. Further, even in a mixed gas atmosphere, gases other than hydrogen do not permeate the hydrogen permeable membrane and can selectively permeate only hydrogen. Furthermore, since the semiconductor layer is affected by the presence or absence of hydrogen that has passed through the hydrogen permeable membrane and absorbed by the hydrogen absorber, the resistance value of the semiconductor layer changes, so that hydrogen can be detected.
Note that this hydrogen detection can be performed at normal temperature without the need for heating, and the resistance value of the semiconductor can easily return to the origin when hydrogen desorbs from the hydrogen absorber. Therefore, since it can be used repeatedly at room temperature without using a heater or the like, power consumption can be reduced.

In the hydrogen sensor of the present invention, the amount of phosphorus added in the hydrogen permeable membrane is in the range of 0.1 to 1.0 wt%. According to this configuration, the same effect as described above can be obtained.
The hydrogen sensor of the present invention can be operated at room temperature, and does not cause a change in resistance value between the electrodes in the presence of a combustible gas such as ethane gas, methane gas, or propane gas. According to such a configuration, since the hydrogen permeable membrane does not transmit flammable gases such as methane gas, ethane gas, and propane gas, the resistance value does not change between the electrodes in the presence of these flammable gases. Therefore, only hydrogen can be detected exclusively without being affected by the presence of these combustible gases. In addition, a hydrogen sensor can be operated at room temperature without requiring a heating device, and power consumption can be reduced.

  The hydrogen sensor of the present invention can be operated in an environment in which oxygen is not present, and the resistance value of the semiconductor, which has changed from the initial state due to the absorption of hydrogen into the hydrogen absorber, is the hydrogen from the hydrogen absorber. It is possible to return to the initial state by leaving. According to such a configuration, the resistance value is restored to the initial state by the detachment of hydrogen from the hydrogen absorber, so that it can be restored to the initial state even after hydrogen is detected once and can be used repeatedly. In that case, it is only necessary to install in an environment where hydrogen is not present without performing heat treatment or oxidation treatment after hydrogen desorption. Since hydrogen is released from the hydrogen absorber simply by installing it in an environment where hydrogen is not present, it can be used repeatedly without requiring any special treatment for forcibly leaving the hydrogen absorber.

The hydrogen sensor according to the present invention is characterized in that the semiconductor is made of a non-oxide semiconductor mainly containing any one of silicon, silicon carbide, germanium, silicon germanium, gallium arsenide, gallium nitride, and carbon . According to this configuration, the same effect as described above can be obtained.

  The hydrogen sensor according to the present invention is characterized in that the hydrogen absorber is made of any one of palladium, palladium alloy, platinum, and platinum alloy, and is arranged as an island-shaped dispersion structure on the semiconductor. According to this configuration, the same effect as described above can be obtained. In addition, when the hydrogen absorber is formed on a semiconductor, the hydrogen absorber is thinner than the particles connected to form a film and does not conduct as a film, that is, the insulation in which the particles are dispersed in an island shape. By forming it on the semiconductor as a body, the resistance value of the semiconductor between the paired electrodes is greatly reduced because the resistance value is much lower than that of the semiconductor that occurs when it is simply formed into a film shape. Can be avoided.

In the hydrogen detection method of the present invention, a hydrogen absorber is attached to the surface of a semiconductor, the exposed surface of the hydrogen absorber is covered with a hydrogen permeable film made of silicon oxide to which phosphorus is added, and the hydrogen permeable film is interposed therebetween. The presence of hydrogen is detected by measuring a change in resistance value of the semiconductor caused by the hydrogen absorber absorbing hydrogen. According to this method, it is possible to detect hydrogen with a low response speed and a high response speed when hydrogen passes through the hydrogen permeable membrane. Gas other than hydrogen can be prevented from passing through the hydrogen permeable membrane, and only hydrogen can be detected.
The hydrogen detection method of the present invention is characterized in that the amount of phosphorus added in the hydrogen permeable membrane is in the range of 0.1 to 1.0 wt%. According to this method, the same effect as described above can be obtained.

According to the hydrogen permeable membrane of the present invention, there are effects that hydrogen is selectively permeated and resistance when hydrogen permeates is small.
According to the hydrogen sensor of the present invention, since the resistance when hydrogen permeates through the hydrogen permeable membrane is small, it is possible to suppress a decrease in response speed. That is, it is possible to obtain a hydrogen sensor having a protective film and a high response speed.
Further, even in a mixed gas atmosphere, gases other than hydrogen do not permeate the hydrogen permeable membrane and can selectively permeate only hydrogen. Furthermore, the presence or absence of hydrogen that has passed through the hydrogen permeable membrane and is absorbed by the hydrogen absorber affects the semiconductor layer, and the resistance value of the semiconductor layer changes, so that hydrogen can be detected.
According to the hydrogen detection method of the present invention, since the resistance when hydrogen permeates through the hydrogen permeable membrane is small, hydrogen detection with a high response speed becomes possible.

A configuration of an embodiment of a hydrogen sensor according to the present invention will be described with reference to the drawings. In all of the following drawings, the film thicknesses and dimensional ratios of the constituent elements are appropriately varied in order to make the drawings easy to see.
1 and 2 show a configuration of a hydrogen sensor according to the present invention. In this hydrogen sensor A, a semiconductor layer 2 is laminated on almost the entire upper surface of an insulating substrate (insulating base) 1. A thin film insulating layer 3 made of Si ₃ N ₄ is formed on the upper surface. Further, a hydrogen absorber 4 having a structure in which particles are dispersed and arranged in an island shape is formed on the upper surface of the thin film insulating layer 3, and a hydrogen permeable film 5 is formed so as to cover the exposed surface of the hydrogen absorber 4. Yes. Further, the inner electrodes 6, 6 are positioned on the surface of the semiconductor layer 2 and on the left and right sides of the previous hydrogen absorber 4, and The outer electrodes 7 and 7 are formed so as to be located on both the left and right sides and further outside the inner electrodes 6 and 6.

As the insulating substrate 1, a substrate made of an insulating material such as a glass substrate such as SiO ₂ , a quartz substrate, a ceramic substrate such as Al ₂ O _3, or an Si substrate as an insulating substrate not doped with ions can be used. A sapphire substrate can also be used. Since the insulating substrate 1 only needs to have insulating properties on the upper surface side, the insulating substrate 1 may be formed by coating an insulating layer on the surface of the conductive substrate. The semiconductor layer 2 is a layered layer made of a semiconductor such as n-type Si doped with ITO (indium tin oxide), GaN, or P. The semiconductor layer 2 is originally an insulator but is preferably a semiconductor doped with ions. As this type of semiconductor, an n-type semiconductor obtained by ion doping silicon with an element such as P, As or Sb, which is a group V element, or a p-type semiconductor obtained by ion doping silicon with a group III element such as B, etc. Can be used. In addition, any of n-type or p-type SiC, Ge, SiGe, GaAs, GaN , or carbon containing diamond can be used as a semiconductor for forming the semiconductor layer 2. In addition, by forming the thin film insulating layer 3 on the surface of the semiconductor layer 2, the protective function of the surface of the semiconductor layer 3 can be ensured. Examples of the thin film insulating layer 4 include Si ₃ N ₄ .

  The hydrogen absorber (hydrogen absorbing / discharging material body) 4 is made of particles made of any one of Pd, Pd alloy, Pt, and Pt alloy, or other platinum group elements or their alloy elements dispersed in an island shape. It is preferable that it is the structure made. In addition to these metals, it is of course possible to use any of La, Ti, Zr, Mg, rare earth metals, Ca, V, or alloys containing these, which are generally known as hydrogen storage alloys. . Here, the hydrogen absorber 4 is made of the above-described metal or alloy hydrogen absorbing / discharging material. When these hydrogen absorbing / discharging materials are formed on the insulating thin film layer 3, the pair of electrodes formed later are electrically connected. It is necessary to make the pattern not to be allowed. Photolithographic methods are preferably used for pattern formation. As another form, it is preferable that the particles are dispersed in an island-like state and do not have conductivity as a whole and function as an insulator. In FIG. 1 and FIG. 2, this hydrogen absorber 4 is abbreviated as a film. Since the hydrogen absorber 4 is separated from the electrode in the patterns of FIGS. 1 and 2, the effect of the present invention is obtained even if it is a continuous film. However, when the hydrogen absorber 4 is enlarged, particles are separated into islands and formed. More preferably, the film thickness is such that it functions as an insulator of the aggregate. For example, the hydrogen absorber 4 is an insulator having a resistance value of about 1 MΩ or more, and the thickness of the hydrogen absorber 4 is preferably in the range of about 0.5 nm to 5 nm.

  Such a hydrogen absorber 4 dispersed in an island shape is in a state before being formed as a film when a film is deposited by depositing particles on the thin film insulating layer 3 by a film deposition method such as a vacuum evaporation method or a sputtering method. The film can be manufactured by stopping the film formation. For example, Pd, Pd alloy, Pt, Pt alloy, etc. are all highly conductive metal materials, and when formed as a film, become a conductor, so that the film formation is stopped in the state of an insulator before becoming a conductor. For example, the hydrogen absorber 3 having a structure in which a plurality of particles are dispersed and arranged in an island shape can be obtained. Therefore, the hydrogen absorber 4 as an insulator can be formed on the thin film insulating layer 3 if it is formed in the range of the film thickness described above. In this form, the vertical width of the hydrogen absorber 4 is slightly shorter than the vertical width of the insulating substrate 1, and the horizontal width is formed to be a fraction of the horizontal width of the insulating substrate 1. Therefore, the semiconductor layer 2 is exposed on both the left and right sides of the hydrogen absorber 4 in FIGS.

  The hydrogen permeable film 5 is formed so as to cover the hydrogen absorber 4 by a film forming method such as a sputtering method in which a film forming source such as a silicon dioxide target to which phosphorus is added is prepared in advance. The film thickness of the hydrogen permeable membrane 5 is preferably 0.5 nm to 5 nm. When the film thickness is 0.5 nm or less, there is a possibility that the film has a slight sensitivity to the flammable gas. When the film thickness is 5 nm or more, the resistance when hydrogen passes through the hydrogen permeable film 5 increases. As a result, the response speed becomes slow, which is not preferable for a hydrogen sensor. Moreover, it is preferable that the addition amount of phosphorus is in the range of 0.1 wt% to 1.0 wt%. When the added amount of phosphorus is 0.1 wt% or less, the resistance when hydrogen permeates the hydrogen permeable membrane 5 is increased, and the response speed is accordingly slowed, which is not preferable as a hydrogen sensor. There is a possibility that phosphorus accumulates in a reaction vessel such as a sputtering apparatus and contaminates the inside of the vessel.

  The inner electrode 6 is formed on the upper surface of the semiconductor layer 2 so as to be separated from the hydrogen absorber 4 so as to be sandwiched between both sides of the hydrogen absorber 4. These inner electrodes 6 are made of a highly conductive metal material such as Au or Al, and are formed by a film forming method such as a vacuum evaporation method, a sputtering method, or a screen printing method. The outer electrodes 7, 7 are formed on both ends of the semiconductor layer 2 at positions where the inner electrodes 6, 6 are further sandwiched from both sides.

  In order to detect hydrogen using the hydrogen sensor A configured as described above, the hydrogen sensor A is installed in a measurement environment, and a predetermined current is applied between the outer electrodes 7 and 7 while the inner electrodes 6 and 6 are applied. It is used by measuring the electric resistance change of the semiconductor layer 2 itself by measuring the voltage between the six. Here, the measurement by the inner electrodes 6 and 6 corresponds to a change in electric resistance of the semiconductor layer 2 itself. When hydrogen gas is present in the installation environment of the hydrogen sensor A, the hydrogen gas permeates through the hydrogen permeable membrane, and hydrogen is taken into the hydrogen absorber 4 of the hydrogen sensor A, and the semiconductor layer 2 absorbs hydrogen through the thin film insulating layer 3. In the portion connected to the body 4, the state of charge carriers changes due to the absorption of hydrogen into the hydrogen absorber 4, and as a result, the resistance value of the semiconductor layer 2 changes. Further, when hydrogen disappears from the environment in which the hydrogen sensor A of this example is installed, hydrogen is released from the hydrogen absorber 4, so that the resistance value of the semiconductor layer 2 returns to the origin and becomes usable again. When hydrogen gas is present again in the installation environment from this state, the semiconductor layer 2 changes its resistance value again, so that the hydrogen sensor A of this example can be used repeatedly.

  The installation environment of the hydrogen sensor A may be normal temperature, but it may be particularly low temperature or high temperature environment. Conventional hydrogen sensors generally operate at high temperatures, and after hydrogen detection, they could not be reused unless heated to a high temperature of about 200 to 300 ° C. and reoxidized. With the hydrogen sensor A, the origin can be returned to the initial stage simply by leaving it in a room temperature environment without hydrogen after detection and can be reused.

  The hydrogen permeable film 5 of the present invention can also function as a protective film for the semiconductor layer 2 by covering the upper surface of the semiconductor layer 2. In addition, since the hydrogen permeable membrane 5 of the present invention has better measurement sensitivity than the conventional hydrogen permeable membrane, high measurement sensitivity can be obtained even if the film thickness is larger than that of the conventional hydrogen permeable membrane. Therefore, the function as a protective film can be easily improved by increasing the film thickness as compared with the conventional hydrogen permeable film.

  The technical scope of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.

(Example 1)
1 and FIG. 2, a GaN film doped with 0.05 μm thick silicon is formed on a sapphire substrate having a length of 3 mm, a width of 3 mm, and a film thickness of 0.43 mm, and Si ₃ N is formed thereon. _A thin film insulating layer 3 made of ₄ was formed. An island-shaped film of a hydrogen absorber 4 having a thickness of 12 mm and made of rectangular Pd having a length of 2.5 mm and a width of 1 mm was formed on the upper surface of the thin film insulating layer 3. The film of the hydrogen absorber 4 was an insulator on the thin film insulating layer. Next, a hydrogen permeable film 5 in which SiO ₂ was doped with phosphorus was formed to a thickness of 20 mm so as to cover the hydrogen absorber 4. Three types of hydrogen permeable membranes were prepared with the amount of P (phosphorus) doped with respect to SiO ₂ being 0.1 wt%, 0.5 wt%, and 1.0 wt%, respectively.

Next, on the GaN film, on both sides of the hydrogen absorber 4 and at a position separated from the hydrogen absorber 4, an inner electrode 6 made of a Ti / Au layer having a length of 2.5 mm and a width of 0.3 mm is provided. 6 (inner electrode having a laminated structure in which an Au layer is formed on a Ti layer as a base) was formed, and outer electrodes 7 and 7 made of a Ti / Au layer were formed 0.3 mm outside these inner electrodes. . The hydrogen gas sensor A having this configuration is housed in a measurement chamber (not shown) and is set to an air atmosphere (100% air) at 25 ° C. (approximately normal temperature), or an air atmosphere containing hydrogen gas (hydrogen gas 0.3%). % + Air 99.7%, or hydrogen gas 0.5% + air 99.5%, or hydrogen gas 1% + air 99%), and the hydrogen gas detection test was repeated. . 3A is a hydrogen permeable membrane with 0.1 wt% phosphorus added, FIG. 3B is a hydrogen permeable membrane with 0.5 wt% phosphorus added, and FIG. 3C is 1.0 wt% phosphorus added. It is a result of the measurement voltage at the time of using a hydrogen permeable membrane, respectively.
In FIGS. 3A to 3C, the time point when the air atmosphere is switched to the hydrogen-containing air atmosphere is a point a, and the time point when the air atmosphere is switched to the hydrogen-containing air atmosphere is a point b.

From the results shown in FIGS. 3A to 3C, it was found that when the air atmosphere was switched to the hydrogen gas-containing air atmosphere, the resistance value immediately decreased, and the measurement voltage decreased accordingly. Here, the stable voltage in the air atmosphere is the pre-operation voltage Va, the stable voltage after switching to the hydrogen gas-containing air atmosphere is the post-operation voltage Vb, the change is the change voltage Vc, and the output sensitivity is Vc / Va. × 100 (%)
, The output sensitivities are as shown in Table 1, and it was found that the addition of 1.0 wt% phosphorus showed the best output sensitivity, and a tendency as shown in FIG. 4 was observed. Moreover, according to the result of FIG. 3, it turned out that resistance value increases rapidly by switching to an air atmosphere after switching to a hydrogen gas containing air atmosphere, and the measurement voltage increases in connection with it.

Moreover, when the output sensitivity after repeating the substitution of the atmosphere containing hydrogen gas (hydrogen gas 0.3% + air 99.7%) and air atmosphere three times, the output sensitivity is as shown in Table 2, respectively. It was found that the output sensitivity of the first measurement almost coincided with the output sensitivity.
Similarly, hydrogen gas-containing air atmosphere and air atmosphere are repeated 9 times in total for hydrogen gas 0.5% and 1% after hydrogen gas 0.3% and substitution of hydrogen gas-containing air atmosphere and air atmosphere three times each. Was replaced.

  As a result, in the hydrogen sensor of this example, it was possible to detect hydrogen gas repeatedly and with good reproducibility only by returning to the atmosphere without performing any special treatment. Furthermore, since this reaction is a measurement result at approximately room temperature of 25 ° C., it is not necessary to heat with a heater, and power consumption can be reduced compared to a conventional hydrogen sensor that has to be measured while heating with a heater. In addition, since it operates at room temperature, it is clear that the hydrogen absorber is less likely to oxidize and the life can be extended.

  FIG. 5 shows the change in output voltage before and after switching from the air atmosphere to the hydrogen gas-containing air atmosphere. Here, the time point when the atmosphere is switched from the atmosphere to the hydrogen gas containing atmosphere is defined as a switching point c, the point at which the post-operation voltage Vb is stabilized is defined as an output stable point d, and the time from the switching point c to the output stable point d is defined as a response time. In this case, when switching from the air atmosphere to the hydrogen gas-containing air atmosphere, the resistance value immediately decreases, and the measurement voltage also decreases accordingly. After 100 seconds, the voltage stabilizes and the hydrogen detection is completed. I understood.

(Example 2)
As in Example 1, three hydrogen sensors using a hydrogen permeable membrane 5 doped with 1.0 wt% phosphorus with respect to SiO ₂ were prepared, and experiments similar to Example 1 were performed at −10 ° C. and 25 ° C. , And performed at three temperature conditions of 130 ° C.
6A shows the experimental results at −10 ° C., FIG. 6B shows the experimental results at 25 ° C., and FIG. As shown in FIGS. 6A to 6C and Table 3, sensitivity characteristics necessary for hydrogen detection were obtained under any temperature condition. In particular, the best sensitivity characteristics were obtained at 25 ° C.

(Comparative example)
As a comparative example, an experiment was performed under the same conditions as in the example using a hydrogen sensor prepared in the same manner as in the example except that SiO ₂ was not doped with phosphorus.
7A shows measurement results at −10 ° C., FIG. 7B shows measurement results at 25 ° C., and FIG. 7C shows measurement results at 130 ° C. FIG. 8 shows the change in output voltage before and after switching from the air atmosphere at 25 ° C. to the hydrogen gas-containing air atmosphere. Here, the time point when the atmosphere is switched from the atmosphere to the hydrogen gas containing atmosphere is defined as a switching point c, the point at which the post-operation voltage Vb is stabilized is defined as an output stable point d, and the time from the switching point c to the output stable point d is defined as a response time. In this case, the response time took 180 seconds, and it was found that the response speed was worse than that of the example. As for the temperature characteristics, it was found that the output sensitivity was very small in the case of −10 ° C. and 25 ° C.

  As described above, according to the hydrogen sensor using the hydrogen permeable membrane of the present invention, it can be seen that the response time is shortened and the response speed is dramatically improved as compared with the conventional hydrogen sensor. It can also be seen that the output sensitivity is dramatically improved at room temperature as compared with the conventional hydrogen sensor.

  As an application example of the present invention, a hydrogen storage tank such as a fuel cell, and a fuel cell vehicle equipped with the same, or a hydrogen gas station for supplying hydrogen gas to the fuel cell vehicle as a hydrogen gas leak detector Can be provided.

It is a side view of the hydrogen sensor concerning the present invention. It is a top view of the hydrogen sensor concerning the present invention. It is a figure which shows the measurement voltage at the time of changing the addition amount of phosphorus in 1st Example of this invention, (A) is 0.1%, (B) is 0.5%, (C) is 1 It is a figure at the time of adding 0.0% of phosphorus. It is a figure which shows the output sensitivity at the time of changing the addition amount of phosphorus in 1st Example of this invention. It is an enlarged view which shows the measurement voltage in the 1st Example of this invention. It is a figure which shows the measurement voltage in the 2nd Example of this invention, (A) is -10 degreeC, (B) is 25 degreeC, (C) is a figure of the measurement voltage in 130 degreeC. It is a figure which shows the measurement voltage at the time of changing the test temperature in a comparative example, (A) is -10 degreeC, (B) is 25 degreeC, (C) is a figure of the measurement voltage in 130 degreeC. It is an enlarged view which shows the measurement voltage in a comparative example.

Explanation of symbols

A ... hydrogen sensor, 1 ... insulating substrate, 2 ... semiconductor film, 3 ... thin film insulating layer, 4 ... hydrogen absorber, 5 ... hydrogen permeable membrane, 6 ... inside Electrode, 7 ... external electrode, c ... switching point, d ... output stability point

Claims (10)

  A hydrogen permeable film comprising silicon oxide to which phosphorus is added.   2. The hydrogen permeable membrane according to claim 1, wherein the amount of phosphorus added is in the range of 0.1 to 1.0 wt%.   A semiconductor, a hydrogen absorber attached to at least a part of the surface of the semiconductor, a hydrogen permeable film that covers the exposed surface of the hydrogen absorber and transmits hydrogen, and an attachment position of the hydrogen absorber, The semiconductor includes a pair of electrodes arranged so as not to be conducted by the hydrogen absorber, the hydrogen permeable film is made of silicon oxide to which phosphorus is added, and hydrogen absorption to the hydrogen absorber is present. A hydrogen sensor characterized in that the presence of hydrogen can be detected by measuring a change in resistance value of the semiconductor corresponding to the above between the pair of electrodes.   The hydrogen sensor according to claim 3, wherein the amount of phosphorus added to the hydrogen permeable membrane is in the range of 0.1 to 1.0 wt%.   5. The hydrogen sensor according to claim 3, wherein the hydrogen sensor can operate at normal temperature and does not cause a change in resistance value between the electrodes in the presence of a combustible gas such as ethane gas, methane gas, and propane gas.   It is operable in an environment where oxygen is not present, and the resistance value of the semiconductor changed from the initial state due to the absorption of hydrogen into the hydrogen absorber is changed to the initial state due to the release of hydrogen from the hydrogen absorber. The hydrogen sensor according to any one of claims 3 to 5, wherein the hydrogen sensor is capable of returning. The said semiconductor consists of a non-oxide semiconductor which has as a main component any one of silicon, silicon carbide, germanium, silicon germanium, gallium arsenide, gallium nitride, and carbon. The hydrogen sensor described in 1.   The said hydrogen absorber consists of either palladium, a palladium alloy, platinum, and a platinum alloy, and has been arrange | positioned as an island-like dispersion structure on the said semiconductor, The any one of Claims 3-7 characterized by the above-mentioned. Hydrogen sensor.   A hydrogen absorber is attached to the surface of the semiconductor, the exposed surface of the hydrogen absorber is covered with a hydrogen permeable film made of silicon oxide to which phosphorus is added, and the hydrogen absorber absorbs hydrogen through the hydrogen permeable film. A method for detecting hydrogen, wherein the presence of hydrogen is detected by measuring a change in resistance value of the semiconductor caused by the above. The method for detecting hydrogen according to claim 9, wherein an addition amount of the phosphorus in the hydrogen permeable membrane is in a range of 0.1 to 1.0 wt%.

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