A palladium-based multilayer film hydrogen sensor based on abnormal Hall effect and a preparation method and application thereof

Abstract

This invention relates to the field of hydrogen sensors, and more particularly to a palladium-based multilayer hydrogen sensor based on the anomalous Hall effect, its fabrication method, and its applications. The palladium-based multilayer hydrogen sensor based on the anomalous Hall effect comprises, from bottom to top, a substrate, a thin film structure with a Hall bar pattern, and an electrode layer; the thin film structure with the Hall bar pattern comprises, from bottom to top, a Pd monolayer thin film and a (Co / Pd) layer. X Multilayer thin film, where X represents (Co / Pd) X The number of cycles in the multilayer thin film; X is an integer from 1 to 10; the (Co / Pd) X In each cycle of the multilayer thin film, a Co layer is arranged at the bottom and a Pd layer at the top. The palladium-based multilayer hydrogen sensor based on the anomalous Hall effect described in this invention has the advantages of a clear hydrogen detection current signal, strong resistance to environmental gas interference, and controllable hydrogen detection concentration.

Description

Technical Field

[0001] This invention relates to the field of hydrogen sensors, and more particularly to a palladium-based multilayer hydrogen sensor based on the anomalous Hall effect, its preparation method, and its application. Background Technology

[0002] Hydrogen is a highly efficient combustion energy source with pollution-free and renewable byproducts, making it widely used in various industrial fields such as aviation, chemical industry, and metal smelting. However, due to the small size and colorless and odorless nature of hydrogen molecules, leaks are extremely prone to occur undetected during production, storage, and transportation. Furthermore, hydrogen has a low ignition point of only 585°C, and when mixed with air at concentrations between 4% and 75%, it is highly explosive upon contact with an open flame. Therefore, researching and developing highly sensitive hydrogen sensors with fast response times is of paramount importance for the safe use of hydrogen energy.

[0003] Currently, the main categories of hydrogen sensors include metal oxide semiconductor sensors, electrochemical hydrogen sensors, fiber optic hydrogen sensors, and surface acoustic wave (SAW) hydrogen sensors. However, existing technologies often suffer from various problems in hydrogen detection: such as interference from other gases (carbon dioxide, methane, oxygen, etc.), leading to false alarms or decreased accuracy; high operating temperatures resulting in increased energy consumption and safety issues; limited lifespan, with sensor materials depleting or failing after a limited number of cycles; and strong environmental dependence, requiring additional calibration in temperature- or humidity-sensitive environments.

[0004] The detection mechanism of common hydrogen sensors typically relies on the alteration of electrical signals by hydrogen. This alteration generally falls into two categories: one is the direct change in resistivity / conductivity / current caused by electron concentration after the sensor surface comes into contact with hydrogen, leading to hydrogen reading and detection; the other is the alteration of the electronic structure of the sensor material by hydrogen, causing a change in the sensor's anomalous Hall signal, thus enabling hydrogen concentration detection. While the first type of hydrogen sensor, based on electron concentration, has an extremely fast response speed, it is highly susceptible to interference from other gases or environmental factors, resulting in inaccurate readings. The second type, based on changes in electronic structure, is virtually free of false alarms, but research on this type is limited and faces significant challenges, such as whether the difference in electrical signals between hydrogen-containing and non-hydrogen-containing environments is sufficiently large to differentiate between them. Therefore, designing and developing hydrogen sensors based on changes in electronic structure is of great importance. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the purpose of this invention is to provide a palladium-based multilayer hydrogen sensor based on the anomalous Hall effect, its preparation method and application, aiming to solve the problem that existing hydrogen sensors are easily affected by interference from other gases or environmental factors, resulting in inaccurate accuracy.

[0006] The technical solution of the present invention is as follows:

[0007] In a first aspect, the present invention provides a palladium-based multilayer hydrogen sensor based on the anomalous Hall effect, comprising a substrate arranged sequentially from bottom to top, a thin film structure having a Hall bar pattern, and an electrode layer.

[0008] The thin film structure with Hall bar pattern comprises, from bottom to top, a Pd monolayer thin film and a (Co / Pd) film. X Multilayer thin film, where X represents (Co / Pd) X The number of cycles in a multilayer thin film;

[0009] X is an integer from 1 to 10;

[0010] The (Co / Pd) X In each cycle of the multilayer thin film, the Co layer is arranged at the bottom and the Pd layer at the top.

[0011] Optionally, the substrate is Gd3Sc2Ga3O 12 A single-crystal substrate or a silicon substrate with a SiO2 layer on its surface; the electrode layer is made of a conductive metal.

[0012] Optionally, the thickness of the Pd monolayer film is 3–10 nm; the (Co / Pd) film... X In the multilayer thin film, the Co layer has a thickness of 0.5–1.2 nm, and the Pd layer has a thickness of 3–10 nm.

[0013] A second aspect of the present invention provides a method for fabricating a palladium-based multilayer hydrogen sensor based on the anomalous Hall effect, comprising the steps of:

[0014] S1. Provide a substrate, and sequentially deposit a Pd monolayer thin film and a (Co / Pd) film on the substrate using vacuum magnetron sputtering. X Multilayer thin films;

[0015] S2. Using photolithography and etching methods, the Pd monolayer film and (Co / Pd) on the substrate are separated. X Multilayer thin films are etched into a thin film structure with Hall bar patterns;

[0016] S3. An electrode layer is formed on the thin film structure with the Hall bar pattern to obtain the palladium-based multilayer hydrogen sensor based on the anomalous Hall effect.

[0017] Optionally, in step S1, the vacuum magnetron sputtering process is as follows: under the condition of argon gas introduction, the vacuum degree is set to be less than or equal to 1×10⁻⁶. -6The sputtering pressure was 3–5 mTorr, the sputtering temperature was room temperature, and the stage rotation speed was 10–40 rpm.

[0018] Optionally, in step S1, the Pd monolayer film and (Co / Pd) X The Pd layers in the multilayer thin films are all sputtered using an RF power supply. The sputtering power of the RF power supply is 40-60W, and the sputtering time is 1-5min.

[0019] The (Co / Pd) X The Co layer in the multilayer thin film is sputtered using a DC power supply with a sputtering power of 40–60 W and a sputtering time of 15–60 s.

[0020] Optionally, step S2 specifically includes:

[0021] In the deposition of Pd monolayer films and (Co / Pd) X Photoresist is coated onto a substrate of a multilayer thin film, and the photoresist is exposed and developed according to a Hall bar pattern.

[0022] The substrate is etched using ion beam etching to peel off the thin film not protected by photoresist, and the photoresist is removed to obtain a thin film structure with a Hall bar pattern.

[0023] Optionally, step S3 specifically includes:

[0024] Photoresist is applied to the thin film structure with the Hall bar pattern, and the photoresist is exposed and developed according to the electrode pattern.

[0025] The electrode material is deposited, the photoresist is removed, and a patterned electrode layer is formed to obtain the palladium-based multilayer hydrogen sensor based on the anomalous Hall effect.

[0026] A third aspect of the present invention provides an application of the palladium-based multilayer hydrogen sensor based on the anomalous Hall effect described herein in the detection of hydrogen concentration.

[0027] Optionally, the hydrogen concentration in the external environment is 0.1% to 15%.

[0028] Beneficial effects: The palladium-based multilayer hydrogen sensor based on the anomalous Hall effect provided by this invention utilizes hydrogen to affect the electronic structure of the Pd layer, resulting in a change in the anomalous Hall signal, thereby detecting the hydrogen concentration; and by changing the (Co / Pd) ratio... XThe number of cycles in the multilayer thin film can adjust the sensor's sensitivity to hydrogen concentration; the lower the cycle, the lower the hydrogen sensitivity, thus enabling the detection of different hydrogen concentrations. The palladium-based multilayer film hydrogen sensor based on the anomalous Hall effect described in this invention has the advantages of a clear hydrogen detection current signal, strong resistance to environmental gas interference, and controllable hydrogen detection concentration. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the Pd / (Co / Pd)3 thin film structure deposited on the substrate in Example 1.

[0030] Figure 2 This is a schematic diagram of the thin film pattern after development in Example 1.

[0031] Figure 3 This is a schematic diagram of the hydrogen sensor prepared in Example 1.

[0032] Figure 4 This is a schematic diagram of anomalous Hall effect detection.

[0033] Figure 5 The image shows the Hall resistance curves of the hydrogen sensor prepared in Example 1 as a function of magnetic field at different hydrogen concentrations.

[0034] Figure 6 The image shows the Hall resistance curves of the hydrogen sensor prepared in Example 2 as a function of magnetic field at different hydrogen concentrations.

[0035] Figure 7 The image shows the Hall resistance curves of the hydrogen sensor prepared in Example 3 as a function of magnetic field at different hydrogen concentrations. Detailed Implementation

[0036] This invention provides a palladium-based multilayer hydrogen sensor based on the anomalous Hall effect, its fabrication method, and its application. To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the invention is further described in detail below. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0037] This invention provides a palladium-based multilayer hydrogen sensor based on the anomalous Hall effect, comprising a substrate arranged sequentially from bottom to top, a thin film structure having a Hall bar pattern, and an electrode layer;

[0038] The thin film structure with Hall bar pattern comprises, from bottom to top, a Pd monolayer thin film and a (Co / Pd) film. X Multilayer thin film, where X represents (Co / Pd) X The number of cycles in a multilayer thin film;

[0039] X is an integer from 1 to 10 (X is 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10);

[0040] The (Co / Pd) X In each cycle of the multilayer thin film, the Co layer is arranged at the bottom and the Pd layer at the top.

[0041] This invention enables the detection of hydrogen concentration using the anomalous Hall effect in a hydrogen sensor. The anomalous Hall effect refers to the deflection of charge carriers in magnetic materials due to the internal properties of the material, perpendicular to the current and magnetization directions. It is commonly characterized by anomalous Hall resistance or anomalous Hall resistivity.

[0042] The palladium-based multilayer hydrogen sensor based on the anomalous Hall effect described in this invention primarily relies on the fact that hydrogen affects the electronic structure of the Pd multilayer film, resulting in a change in the anomalous Hall signal, thereby detecting the hydrogen concentration; and further, by changing the (Co / Pd) ratio... X The number of cycles in the multilayer thin film can adjust the sensor's sensitivity to hydrogen concentration; a lower cycle number results in lower hydrogen sensitivity, thus enabling the detection of different hydrogen concentrations. Pd, as a hydrogen-reactive material, can rapidly adsorb and dissociate hydrogen, causing lattice expansion and changes in the Pd electronic band structure, resulting in a rapid electrical signal response to a hydrogen environment. At room temperature and pressure, Pd only has a catalytic effect on hydrogen (dissociation and desorption), and because hydrogen is a small molecule with small atom size, a high diffusion rate, and strong interaction with the lattice, the palladium-based multilayer hydrogen sensor provided in this invention has the advantages of a clear hydrogen detection current signal, strong resistance to environmental gas interference, and controllable hydrogen detection concentration.

[0043] The method and principle of detecting hydrogen concentration using a palladium-based multilayer hydrogen sensor based on the anomalous Hall effect described in this invention embodiment are as follows: For a thin film structure with a Hall bar pattern, a fixed current I is applied in the longitudinal direction, and a magnetic field Hz is applied in the direction perpendicular to the thin film structure. The transverse Hall voltage U is measured, and the Hall resistance R = U / I is obtained. The hydrogen concentration of the external environment is fed back based on the Hall resistance signal, thereby realizing the detection of hydrogen concentration in the external environment.

[0044] In this embodiment, the thin film structure with Hall bar pattern comprises, from bottom to top, a Pd monolayer thin film and a (Co / Pd) film. X Multilayer thin film, where X represents (Co / Pd) XThe number of cycles in the multilayer thin film, X, is an integer from 1 to 10, specifically 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10. When X is 1, the thin film structure with the Hall bar pattern consists of a multilayer thin film structure of Pd layer / Co layer / Pd layer from bottom to top; when X is 2, the thin film structure with the Hall bar pattern consists of a multilayer thin film structure of Pd layer / (Co layer / Pd layer)2 from bottom to top; when X is 3, the thin film structure with the Hall bar pattern consists of a multilayer thin film structure of Pd layer / (Co layer / Pd layer)3 from bottom to top; and the corresponding thin film structure with the Hall bar pattern can be obtained similarly when X is any other integer. In some preferred embodiments, X is an integer from 1 to 3, specifically 1, 2, or 3.

[0045] In this embodiment, the thin-film structure with Hall bar patterns exhibits some shapes commonly used in Hall devices, such as rectangular, cross-shaped, square, and four-leaf clover-shaped thin-film structures. Different sizes and shapes of the Hall bar patterns have little impact on the hydrogen concentration detected by the hydrogen sensor described in this application; all can effectively control the anomalous Hall effect caused by hydrogen on the thin-film structure with Hall bar patterns, thereby achieving hydrogen concentration detection.

[0046] In some embodiments, the substrate is Gd3Sc2Ga3O 12 A single-crystal substrate or a silicon substrate with a SiO2 layer on its surface. Preferably, the substrate has a (111) crystal orientation and a lattice constant of Gd3Sc2Ga3O 12 (GSGG) Single crystal substrate.

[0047] In some embodiments, the electrode layer is made of a conductive metal, such as Pt, Al, or Ru.

[0048] In some embodiments, the thickness of the Pd monolayer film is 3–10 nm (e.g., 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, etc.); the (Co / Pd) XIn the multilayer thin film, the thickness of the Co layer is 0.5–1.2 nm (e.g., 0.5 nm, 0.6 nm, 0.7 nm, 0.8 nm, 0.9 nm, 1.0 nm, 1.1 nm, 1.2 nm, etc.), and the thickness of the Pd layer is 3–10 nm (e.g., 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, etc.). The Co layer exhibits good perpendicular magnetic anisotropy within the thickness range of 0.5–1.2 nm, and the thinner the Co layer, the lower the hydrogen sensitivity, meaning that the anomalous Hall signal can be reversed even at low hydrogen concentrations. The thickness of the Pd layer is not strictly limited, but if the Pd layer is too thin, such as 1.5 nm, the anomalous Hall signal cannot be reversed in hydrogen. In this invention, the thickness of the Pd layer is limited to 3–10 nm.

[0049] This invention provides a method for fabricating a palladium-based multilayer hydrogen sensor based on the anomalous Hall effect as described in any of the foregoing embodiments, comprising the following steps:

[0050] S1. Provide a substrate, and sequentially deposit a Pd monolayer thin film and a (Co / Pd) film on the substrate using vacuum magnetron sputtering. X Multilayer thin films;

[0051] S2. Using photolithography and etching methods, the Pd monolayer film and (Co / Pd) on the substrate are separated. X Multilayer thin films are etched into a thin film structure with Hall bar patterns;

[0052] S3. An electrode layer is formed on the thin film structure with the Hall bar pattern to obtain the palladium-based multilayer hydrogen sensor based on the anomalous Hall effect.

[0053] The preparation method provided in this invention is simple and efficient. First, a Pd monolayer thin film and a (Co / Pd) film are sequentially deposited on a substrate using vacuum magnetron sputtering. X Multilayer thin films are formed, and then photolithography and etching are used to separate the Pd monolayer thin film and (Co / Pd) on the substrate. X Multilayer thin films are etched into a thin film structure with a Hall bar pattern (etching the thin film into a Hall bar pattern), that is, a thin film structure with a Hall bar pattern is deposited on the substrate (from bottom to top, it includes a Pd monolayer film and a (Co / Pd) film). X The process involves creating a multilayer thin film, and finally depositing an electrode layer on the thin film structure to obtain the palladium-based multilayer hydrogen sensor based on the anomalous Hall effect described in this invention.

[0054] In step S1, in some embodiments, the vacuum magnetron sputtering process is as follows: under the condition of introducing argon gas, the vacuum degree is set to be less than or equal to 1×10⁻⁶. -6The sputtering pressure is 3–5 mTorr (e.g., 3 mTorr, 3.5 mTorr, 4 mTorr, 4.5 mTorr, 5 mTorr), the sputtering temperature is room temperature (generally 25°C), and the sample stage speed is 10–40 rpm (e.g., 10 rpm, 20 rpm, 30 rpm, 40 rpm).

[0055] In some embodiments, the Pd monolayer film and (Co / Pd) X In the multilayer thin films, the Pd layer is sputtered using an RF power supply. This is because the Co layer is extremely thin (0.5–1.2 nm). If a DC power supply is used to sputter the Pd layer, the bombardment energy would be too high, easily causing discontinuities in the Co layer. Consequently, the thin film would not exhibit perpendicular magnetic anisotropy, resulting in no obvious anomalous Hall signal. However, by using an RF power supply sputtering method, the prepared thin film exhibits perpendicular magnetic anisotropy. The sputtering power of the RF power supply is 40–60 W (e.g., 40 W, 45 W, 50 W, 55 W, 60 W), and the sputtering time is 1–5 min (e.g., 1 min, 2 min, 3 min, 4 min, 5 min). The (Co / Pd) X The Co layer in the multilayer thin film can be sputtered using a DC power supply. The sputtering power of the DC power supply is 40-60W (e.g., 40W, 45W, 50W, 55W, 60W), and the sputtering time is 15-60s (e.g., 15s, 20s, 25s, 30s, 35s, 40s, 45s, 50s, 55s, 60s).

[0056] In some implementations, step S1 specifically includes:

[0057] A substrate is provided, and a Pd monolayer thin film and a (Co / Pd) film are sequentially deposited on the substrate in a vacuum magnetron sputtering apparatus. X A multilayer thin film, wherein argon gas is introduced and the vacuum degree is less than or equal to 1×10⁻⁶. -6 Torr, sputtering pressure 3–5 mTorr, sputtering temperature room temperature, sample stage rotation speed 10–40 rpm, when depositing Pd monolayer thin films and (Co / Pd) X The Pd layer in the multilayer thin film is deposited using radio frequency (RF) sputtering with a sputtering power of 40–60 W and a sputtering time of 1–5 min. X The Co layer in the multilayer thin film was deposited by DC sputtering with a power of 40–60 W and a sputtering time of 15–60 s, resulting in a deposited Pd monolayer thin film and (Co / Pd) film. X Substrate for multilayer thin films.

[0058] In some embodiments, step S2 specifically includes:

[0059] In the deposition of Pd monolayer films and (Co / Pd) X Photoresist is coated on a substrate of a multilayer thin film, and the photoresist is exposed and developed according to a Hall bar pattern;

[0060] The substrate is etched using ion beam etching to peel off the thin film not protected by photoresist, and the photoresist is removed to obtain a thin film structure with a Hall bar pattern.

[0061] In some embodiments, step S3 specifically includes:

[0062] Photoresist is applied to the thin film structure with the Hall bar pattern, and the photoresist is exposed and developed according to the electrode pattern.

[0063] The electrode material is deposited, the photoresist is removed, and a patterned electrode layer is formed to obtain the palladium-based multilayer hydrogen sensor based on the anomalous Hall effect.

[0064] In this invention, the exposure and development processes, ion beam etching, photoresist removal, and electrode material deposition are all conventional techniques in the art and are not limited herein.

[0065] This invention provides an application of the palladium-based multilayer hydrogen sensor based on the anomalous Hall effect described in any of the foregoing embodiments in detecting the concentration of hydrogen in the external environment.

[0066] In some embodiments, the hydrogen concentration in the external environment is 0.1% to 15%.

[0067] The present invention will be further described below through specific embodiments.

[0068] Example 1

[0069] This embodiment provides a method for fabricating a palladium-based multilayer hydrogen sensor S1 based on the anomalous Hall effect, as detailed below:

[0070] Step 1: Select the (111) crystal orientation and lattice constant as... Gd3Sc2Ga3O 12 On a (GSGG) single-crystal substrate, a Pd monolayer and three cycles of (Co / Pd) multilayer films were sequentially deposited using a vacuum magnetron sputtering system (AJA Corporation, ATC ORION 8 model). Argon gas was introduced during the deposition, and the vacuum level was set to be less than or equal to 1 × 10⁻⁶. -6The sputtering pressure was 3.5 mTorr, the sputtering temperature was room temperature, and the stage rotation speed was 30 rpm. For the deposition of the Pd layer in both the Pd monolayer and the (Co / Pd)3 multilayer films, RF sputtering with a power of 50 W and a sputtering time of 3 min was used. For the deposition of the Co layer in the (Co / Pd)3 multilayer films, DC sputtering with a power of 50 W and a sputtering time of 25 s was used. Thus, Pd monolayer and (Co / Pd)3 multilayer films were deposited on the GSGG single-crystal substrate, resulting in the following... Figure 1 The Pd / (Co / Pd)3 thin film structure is shown.

[0071] Step 2: Place the substrate with the Pd / (Co / Pd)3 thin film structure on a spin coater, and drop RNRN246 negative photoresist onto the film structure. Set the spin coater speed to 3000 rad / s and continue for 30 s to spin coat a smooth, approximately 3 μm thick layer of photoresist onto the film structure. Then, place the substrate on a heated stage and dry it at 110°C for 90 s to remove the solvent from the photoresist. Next, expose the substrate using a photolithography machine (SUSS MA / BA6 GEN4, Germany) to transfer the Hall-bar pattern from the photomask onto the substrate. Dry the substrate again at 110°C for 90 s to further stabilize the photoresist properties. Then, develop the photoresist using NMD-3 2.38% negative photoresist developer until the denatured photoresist is fully dissolved in the developer, leaving a cross-shaped Hall-bar pattern on the substrate. A schematic diagram of the developed film pattern is shown below. Figure 2 As shown, the longer segment is the current-carrying end with a linewidth of 10 μm, and the shorter segment is the voltage-carrying end with a linewidth of 5 μm. Finally, the substrate is placed in an ion beam etching machine for etching. The high-energy ion beam bombards and removes the thin film not protected by the photoresist, and then the photoresist is removed to obtain a thin film structure with a "+" shaped Hall-bar pattern.

[0072] S3. Coat the substrate obtained in step two evenly with photoresist, dry it at 100°C, expose the transfer electrode pattern on a photolithography machine, develop and clean it, and deposit the electrode layer using a vacuum magnetron sputtering device, wherein the vacuum level is set to less than 5×10⁻⁶. -5 Pa; the sputtering power was 50W, and the DC sputtering time was 14min, that is, a 40nm thick Pt layer was deposited on the thin film structure as an electrode layer. After the electrode layer was deposited, the substrate was ultrasonically cleaned in acetone for 30s to remove the photoresist, that is, a patterned electrode layer was formed on the thin film structure, and finally the palladium-based multilayer hydrogen sensor S1 based on the anomalous Hall effect was obtained. A schematic diagram of the hydrogen sensor S1 is shown below. Figure 3 As shown.

[0073] Example 2

[0074] The preparation method of Example 2 is the same as that of Example 1, except that in step one, a Pd monolayer film and two cycles of (Co / Pd)2 multilayer films are deposited sequentially on the substrate to finally obtain a palladium-based multilayer hydrogen sensor S2 based on the anomalous Hall effect.

[0075] Example 3

[0076] The preparation method of Example 3 is the same as that of Example 1, except that in step one, a Pd monolayer film and a (Co / Pd)1 multilayer film of one cycle are deposited sequentially on the substrate to finally obtain a palladium-based multilayer hydrogen sensor S3 based on the anomalous Hall effect.

[0077] The hydrogen concentration detection performance of palladium-based multilayer film hydrogen sensors S1-S3 based on the anomalous Hall effect prepared in Examples 1-3 above was tested. A mixture of hydrogen and nitrogen was used to simulate the hydrogen concentration in the environment to be detected, with the hydrogen generator producing hydrogen and a high-purity nitrogen (4N) cylinder providing nitrogen. The hydrogen concentration was controlled by mixed gas control software, defined as hydrogen concentration = hydrogen flow rate / (hydrogen flow rate + nitrogen flow rate), as follows:

[0078] For the palladium-based multilayer hydrogen sensors S1-S3 prepared in Examples 1-3 above, mixed gases of hydrogen and nitrogen with different hydrogen concentrations are connected to the anomalous Hall effect resistance measurement device. A fixed current I (I = 10 mA) is applied in the longitudinal direction of its Hall-bar thin film structure, and a varying magnetic field Hz is applied in the direction perpendicular to the thin film structure. The transverse Hall voltage U is measured. A schematic diagram of the anomalous Hall effect detection is shown below. Figure 4 As shown, the Hall voltage U can be obtained from the change of the magnetic field Hz. Dividing U by the fixed current I gives the Hall resistance R. Finally, the Hall resistance curve of the hydrogen sensor as a function of the magnetic field can be obtained.

[0079] Based on the Hall resistance curves of the hydrogen sensor under different hydrogen concentrations as a function of magnetic field, the hydrogen sensitivity point and anomalous Hall resistance change value of the hydrogen sensor can be obtained. The hydrogen sensitivity point refers to the hydrogen concentration when the left and right ends of the Hall resistance curve are equal, that is, the hydrogen concentration when the Hall resistance remains unchanged under positive and negative magnetic fields. The anomalous Hall resistance change value is calculated as (RH1-R0) / R0, where R0 is the anomalous Hall resistance at 0% hydrogen concentration, RH1 is the anomalous Hall resistance at the corresponding hydrogen concentration, and the anomalous Hall resistance RAHE = (Hall resistance corresponding to the maximum positive magnetic field - Hall resistance corresponding to the maximum negative magnetic field) / 2.

[0080] For the hydrogen sensor S1 prepared in Example 1, a varying magnetic field (Hz) of -1000 to 1000 Oe was applied, and the Hall resistance curves of the hydrogen sensor as a function of the magnetic field were tested at hydrogen concentrations of 0%, 4.0%, 7.5%, 7.9%, 8.2%, 9.0%, 10.0%, 11.0%, and 12.0%, as shown below. Figure 5 As shown. According to Figure 5 As can be seen, the anomalous Hall signal flips with increasing hydrogen concentration, changing from left-high to right-low to left-low to right-high. Furthermore, the Hall signal recovers when the hydrogen concentration returns to 0%, indicating that the hydrogen sensor is reusable. In addition, the hydrogen sensor S1 has a hydrogen sensitivity of 8.2% hydrogen concentration, and its anomalous Hall resistance change in hydrogen can reach 180%, ensuring its accuracy and anti-interference capabilities, and minimizing the likelihood of errors.

[0081] For the hydrogen sensor S2 prepared in Example 2, a varying magnetic field (Hz) of -400 to 400 Oe was applied, and the Hall resistance curves of the hydrogen sensor as a function of the magnetic field were tested at hydrogen concentrations of 0%, 1.0%, 2.5%, 2.6%, 3.0%, 3.5%, 4.0%, 5.0%, and 5.5%, as shown below. Figure 6 As shown. According to Figure 6 As can be seen, the anomalous Hall signal flips with increasing hydrogen concentration, changing from left-high to right-low to left-low to right-high. Furthermore, the Hall signal recovers when the hydrogen concentration returns to 0%, indicating that the hydrogen sensor is reusable. In addition, the hydrogen sensor S2 has a hydrogen sensitivity of 2.6% hydrogen concentration, and its anomalous Hall resistance change in hydrogen can reach 206%, ensuring its accuracy and anti-interference capabilities, and minimizing the likelihood of errors.

[0082] For the hydrogen sensor S3 prepared in Example 3, a varying magnetic field (Hz) of -300 to 300 Oe was applied, and the Hall resistance curves of the hydrogen sensor as a function of the magnetic field were tested for hydrogen concentrations of 0%, 0.1%, 0.2%, 0.4%, 0.6%, 1.0%, 1.5%, 2.5%, and 4.0%, respectively. Figure 7 As shown. According to Figure 7 As can be seen, the anomalous Hall signal flips with increasing hydrogen concentration, changing from left-high to right-low to left-low to right-high. Furthermore, the Hall signal recovers when the hydrogen concentration returns to 0%, indicating that the hydrogen sensor is reusable. In addition, the hydrogen sensor S3 has a hydrogen sensitivity of 0.4% hydrogen concentration, and its anomalous Hall resistance change in hydrogen can reach 175%, ensuring its accuracy and anti-interference capabilities, and minimizing the likelihood of errors.

[0083] Furthermore, based on the above data, it can be seen that the sensitivity of the palladium-based multilayer hydrogen sensor based on the anomalous Hall effect provided by this invention to hydrogen can be assessed by (Co / Pd). X The number of cycles in the multilayer thin film is controlled. The lower the cycle, the lower the hydrogen sensitivity. The single-cycle hydrogen sensor flips at a hydrogen concentration of 0.4% (the curve is equal on both sides), the two-cycle hydrogen sensor flips at a hydrogen concentration of 2.6%, and the three-cycle hydrogen sensor flips at a hydrogen concentration of 8.2%.

[0084] In summary, this invention provides a palladium-based multilayer hydrogen sensor based on the anomalous Hall effect, comprising a substrate, a thin film structure with a Hall bar pattern, and an electrode layer arranged sequentially from bottom to top. Hydrogen gas affects the electronic structure of the Pd multilayer film in the structure, generating a change in the anomalous Hall signal, thereby detecting the hydrogen concentration; and by changing the (Co / Pd) ratio... X The number of cycles in the multilayer thin film can adjust the sensor's sensitivity to hydrogen concentration; the lower the cycle, the lower the hydrogen sensitivity, thus enabling the detection of different hydrogen concentrations. The palladium-based multilayer film hydrogen sensor based on the anomalous Hall effect described in this invention has the advantages of a clear hydrogen detection current signal, strong resistance to environmental gas interference, and controllable hydrogen detection concentration.

[0085] It should be understood that the application of the present invention is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A palladium-based multilayer hydrogen sensor based on the anomalous Hall effect, characterized in that, It includes a substrate arranged from bottom to top, a thin film structure with a Hall bar pattern, and an electrode layer; The thin film structure with Hall bar pattern comprises, from bottom to top, a Pd monolayer thin film and a (Co / Pd) film. X Multilayer thin film, where X represents (Co / Pd) X The number of cycles in a multilayer thin film; X is an integer from 1 to 10; The (Co / Pd) X In each cycle of the multilayer thin film, the Co layer is arranged at the bottom and the Pd layer at the top; The thickness of the Pd monolayer film is 3~10 nm; the (Co / Pd) film... X In the multilayer thin film, the Co layer has a thickness of 0.5~1.2 nm, and the Pd layer has a thickness of 3~10 nm; The substrate is Gd3Sc2Ga3O 12 A single-crystal substrate or a silicon substrate with a SiO2 layer on its surface; the electrode layer is made of a conductive metal. By changing (Co / Pd) X The number of cycles in the multilayer thin film modulates the sensitivity of the palladium-based multilayer hydrogen sensor to hydrogen concentration. The method for detecting hydrogen concentration using a palladium-based multilayer hydrogen sensor based on the anomalous Hall effect is as follows: For a thin film structure with a Hall bar pattern, a fixed current I is applied in the longitudinal direction, and a magnetic field Hz is applied in the direction perpendicular to the thin film structure. The transverse Hall voltage U is measured, and the Hall resistance R = U / I is obtained. The hydrogen concentration of the external environment is fed back based on the Hall resistance signal, thereby realizing the detection of hydrogen concentration in the external environment.

2. A method for fabricating a palladium-based multilayer hydrogen sensor based on the anomalous Hall effect as described in claim 1, characterized in that, Including the following steps: S1. Provide a substrate, and sequentially deposit a Pd monolayer thin film and a (Co / Pd) film on the substrate using vacuum magnetron sputtering. X Multilayer thin films; S2. Using photolithography and etching methods, the Pd monolayer film and (Co / Pd) on the substrate are separated. X Multilayer thin films are etched into a thin film structure with Hall bar patterns; S3. An electrode layer is formed on the thin film structure with the Hall bar pattern to obtain the palladium-based multilayer hydrogen sensor based on the anomalous Hall effect.

3. The method for fabricating a palladium-based multilayer hydrogen sensor based on the anomalous Hall effect according to claim 2, characterized in that, In step S1, the vacuum magnetron sputtering process is as follows: under the condition of argon gas introduction, the vacuum degree is set to be less than or equal to 1×10⁻⁶. -6 The sputtering pressure was 3~5 mTorr, the sputtering temperature was room temperature, and the stage rotation speed was 10~40 rpm.

4. The method for fabricating a palladium-based multilayer hydrogen sensor based on the anomalous Hall effect according to claim 3, characterized in that, In step S1, the Pd monolayer film and (Co / Pd) X The Pd layers in the multilayer thin films are all sputtered using an RF power supply. The sputtering power of the RF power supply is 40~60 W, and the sputtering time is 1~5 min. The (Co / Pd) X The Co layer in the multilayer thin film is sputtered using a DC power supply with a sputtering power of 40~60 W and a sputtering time of 15~60 s.

5. The method for fabricating a palladium-based multilayer hydrogen sensor based on the anomalous Hall effect according to claim 2, characterized in that, Step S2 specifically includes: In the deposition of Pd monolayer films and (Co / Pd) X Photoresist is coated onto a substrate of a multilayer thin film, and the photoresist is exposed and developed according to a Hall bar pattern. The substrate is etched using ion beam etching to peel off the thin film not protected by photoresist, and the photoresist is removed to obtain a thin film structure with a Hall bar pattern.

6. The method for fabricating a palladium-based multilayer hydrogen sensor based on the anomalous Hall effect according to claim 2, characterized in that, Step S3 specifically includes: Photoresist is applied to the thin film structure with the Hall bar pattern, and the photoresist is exposed and developed according to the electrode pattern. The electrode material is deposited, the photoresist is removed, and a patterned electrode layer is formed to obtain the palladium-based multilayer hydrogen sensor based on the anomalous Hall effect.

7. The application of the palladium-based multilayer hydrogen sensor based on the anomalous Hall effect as described in claim 1 in detecting the concentration of hydrogen in the external environment.

8. The application of the palladium-based multilayer hydrogen sensor based on the anomalous Hall effect according to claim 7 in detecting the hydrogen concentration in the external environment, wherein the hydrogen concentration in the external environment is 0.1%~15%.

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