Pd / alpha-Ga2O3 sensor for high-sensitivity hydrogen detection as well as preparation method and application of Pd / alpha-Ga2O3 sensor

Abstract

The invention discloses a Pd / alpha-Ga2O3 sensor for high-sensitivity hydrogen detection as well as a preparation method and application of the Pd / alpha-Ga2O3 sensor, an alpha-Ga2O3 layer is deposited on a c-plane sapphire substrate by adopting a fog chemical vapor deposition method, Sn ions with a certain concentration are doped, and then an MSM structure with Schottky contact is prepared for high-sensitivity detection of hydrogen. The result shows that the fluorescent probe has high sensitivity at the detection temperature of 5-60 DEG C, and the response value of the fluorescent probe to 104ppm hydrogen at 25 DEG C reaches 89 at most.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrogen sensors, and in particular to a Pd / α-Ga2O3 sensor for highly sensitive hydrogen detection and a preparation method and application thereof. Background Art

[0002] The use of hydrogen energy has higher safety requirements than other energy sources, and requires highly sensitive and reliable hydrogen sensors to detect hydrogen. 2 Up to 10 5 It has sensitivity to hydrogen in the ppm range with high repeatability of the measurements, low sensitivity to environmental factors, a response speed of less than 1 second and an energy consumption of less than 100 mW.

[0003] Traditional hydrogen sensors include catalytic combustion type, thermal conduction type, electrochemical type, etc. The working principle of catalytic combustion type hydrogen sensor is that in an oxygen environment, hydrogen burns on the surface of platinum catalyst to generate heat, and the hydrogen concentration is estimated by measuring temperature changes, but it has poor selectivity for combustible gases, is easily affected by inhibitors, and requires a higher operating temperature; thermal conductivity type hydrogen sensor estimates hydrogen concentration by measuring the temperature difference between the thermistor and the reference element, but the sensor has low accuracy and will cause cross-sensitivity to high thermal conductivity gases (such as He, CH4, CO, etc.); electrochemical type hydrogen sensor uses the redox reaction of hydrogen on the electrode to generate current, the current size is proportional to the hydrogen concentration, but the sensor has a slow response speed and a short service life.

[0004] However, many metal oxide semiconductors such as SnO2, ZnO, TiO2, etc. are sensitive to the gas composition around them. This gas-sensitive property comes from the significant change in material resistance caused by the interaction between the gas and the surface or body of the semiconductor. These materials have been used to manufacture commercial gas sensors. Sensors based on semiconductor metal oxides and metal chalcogenides have broad application prospects in hydrogen technology. Due to the limitations of traditional semiconductor materials used in sensor technology, it is impossible to meet all requirements in a single device, and its operating temperature is high, the response time is long, and it is prone to baseline drift, resulting in low stability and reliability of the sensor. Therefore, advanced hydrogen sensors require the use of new semiconductor materials and heterostructures. α-Ga2O3, as a new type of semiconductor material, has great potential in hydrogen detection. Summary of the invention

[0005] One of the purposes of the present invention is to provide a method for preparing a Pd / α-Ga2O3 sensor for highly sensitive hydrogen detection.

[0006] The second object of the present invention is to provide a Pd / α-Ga2O3 sensor prepared by the above method.

[0007] The third object of the present invention is to provide the application of the above-mentioned Pd / α-Ga2O3 sensor in hydrogen detection.

[0008] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0009] In a first aspect, the present invention provides a method for preparing a Pd / α-Ga2O3 sensor for highly sensitive hydrogen detection, comprising the following steps:

[0010] Firstly, a 1-2 μm thick α-Ga2O3 layer is deposited on a c-plane sapphire substrate by using a mist chemical vapor deposition method; commercially available gallium acetylacetonate with a purity greater than 99.99% and pure oxygen are used as raw materials, and SnCl4·5H2O is doped in the raw materials; growth is carried out in a mist chemical vapor deposition device, and the growth temperature is set to 450-550°C; a Pd Schottky contact is deposited on the surface of the epitaxial layer by magnetron sputtering using a shadow mask, and the thickness of the Pd layer contact is 300-330nm, so as to form an MSM structure with a Schottky contact, and the wafer is cut into chips.

[0011] Preferably, the Sn donor concentration is 3.8×10 16 cm -3 ~2.3×10 18 cm -3 .

[0012] More preferably, the Sn donor concentration is 2.3×10 18 cm -3 .

[0013] In a second aspect, the present invention provides a Pd / α-Ga2O3 sensor prepared by the above method.

[0014] In a third aspect, the present invention provides application of the above-mentioned Pd / α-Ga2O3 sensor in hydrogen detection.

[0015] The mechanism by which the Pd / α-Ga2O3 sensor is sensitive to H2 is mainly that H2 molecules dissociate and adsorb on the surface of the catalytically active metal Pd, and then H atoms diffuse through the Pd layer to the Pd / α-Ga2O3:Sn interface, transferring electrons to the conduction band of α-Ga2O3. The generated H + The ions localize to the negatively charged surface states at the Pd / α-Ga2O3:Sn interface and neutralize them, resulting in a decrease in the electronic barrier height at the metal-semiconductor interface and an increase in the current.

[0016] The technical solution of the present invention has the following advantages over the prior art:

[0017] The invention provides a Pd / α-Ga2O3 sensor for high-sensitivity hydrogen detection, which has a simple preparation process, is extremely sensitive to hydrogen, has high sensitivity at a detection temperature of 20 to 35°C, and has a high sensitivity to 10 4 The maximum response value of hydrogen in ppm reaches 89, which is very suitable for the safe detection of hydrogen. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is the XRD pattern of α-Ga2O3 layer;

[0019] Figure 2 IV curve of a Pd / α-Ga2O3 sensor for high-sensitivity hydrogen detection prepared in Examples 1 to 4 at 20°C in air;

[0020] Figure 3 A highly sensitive hydrogen detection Pd / α-Ga2O3 sensor prepared in Examples 1 and 4 was exposed to 10 4 The response value under ppm hydrogen changes with temperature;

[0021] Figure 4 Schematic diagram of the interaction between H2 molecules and Pd / α-Ga2O3:Sn interface. DETAILED DESCRIPTION

[0022] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0023] Example 1: Sn concentration is 2.3×10 18 cm -3

[0024] First, a 1.1 μm thick α-Ga2O3 layer was deposited on a c-plane sapphire substrate using a mist chemical vapor deposition method. Commercially available gallium acetylacetonate with a purity greater than 99.99% and pure oxygen were used as raw materials and grown in a mist chemical vapor deposition device at a growth temperature of 500°C. SnCl4·5H2O was doped in the raw materials, and the Sn donor concentration was 2.3×10 18 cm -3 Then, an MSM structure with Schottky and Ohmic contacts was prepared. Pd Schottky contacts were deposited on the surface of the epitaxial layer through a shadow mask. The thickness of the Pd contacts was 320nm. After the contacts were deposited, they were cut into wafers. The distance between adjacent metal contacts in all samples was 1mm.

[0025] Example 2: Sn concentration is 3.8×10 16 cm -3

[0026] First, a 2 μm thick α-Ga2O3 layer was deposited on a c-plane sapphire substrate using a mist chemical vapor deposition method. Commercially available gallium acetylacetonate with a purity greater than 99.99% and pure oxygen were used as raw materials and grown in a mist chemical vapor deposition device at a growth temperature of 450°C. SnCl4·5H2O was doped in the raw materials with a Sn donor concentration of 3.8×10 16 cm -3 Then, an MSM structure with Schottky and Ohmic contacts was prepared. Pd Schottky contacts were deposited on the surface of the epitaxial layer through a shadow mask. The thickness of the Pd contacts was 330 nm. After the contacts were deposited, they were cut into wafers.

[0027] Example 3: Sn concentration is 6.9×10 17 cm -3

[0028] First, a 1 μm thick α-Ga2O3 layer was deposited on a c-plane sapphire substrate using a mist chemical vapor deposition method. Commercially available gallium acetylacetonate with a purity greater than 99.99% and pure oxygen were used as raw materials and grown in a mist chemical vapor deposition device at a growth temperature of 550°C. SnCl4·5H2O was doped in the raw materials with a Sn donor concentration of 6.9×10 17 cm -3 Then, an MSM structure with Schottky and Ohmic contacts was prepared. Pd Schottky contacts were deposited on the surface of the epitaxial layer through a shadow mask. The thickness of the Pd contacts was 300 nm. After the contacts were deposited, they were cut into wafers.

[0029] Example 4: Sn concentration is 4.7×10 17 cm -3

[0030] First, a 1.2 μm thick α-Ga2O3 layer was deposited on a c-plane sapphire substrate using a mist chemical vapor deposition method. Commercially available gallium acetylacetonate with a purity greater than 99.99% and pure oxygen were used as raw materials and grown in a mist chemical vapor deposition device at a growth temperature of 500°C. SnCl4·5H2O was doped in the raw materials, and the Sn donor concentration was 4.7×10 17 cm -3 Then, an MSM structure with Schottky and Ohmic contacts was prepared. Pd Schottky contacts were deposited on the surface of the epitaxial layer through a shadow mask. The thickness of the Pd contacts was 310 nm. After the contacts were deposited, they were cut into wafers.

[0031] Figure 1 is the XRD spectrum of α-Ga2O3 layer; Figure 1 It can be seen that there is a strong diffraction peak at 2θ=40.25°, indicating that the prepared α-Ga2O3 layer is a pure phase single crystal;

[0032] From the attached Figure 2 It can be seen from the curve that in the temperature range of T = 5 to 60°C, it follows a linear relationship, where I is the current and U is the bias applied to the MSM structure. This is consistent with the thermal ion emission model of current transmission in the MSM structure under the diode approximation, indicating that the MSM structure was successfully prepared.

[0033] Attached Figure 4 Schematic diagram of the interaction between H2 molecules and the Pd / α-Ga2O3:Sn interface, where (1) H2 molecules dissociate and adsorb on the Pd surface; (2) H atoms diffuse through the Pd layer to the Pd / α-Ga2O3:Sn interface; (3) H + Ion formation; (4) H + Ions are localized in negatively charged surface states; (5) Reduction of the space charge region (SCR).

[0034] Example 5: Application of gas sensor

[0035] Test method: In 10 4 Under ppm hydrogen, Pd / Ga2O3 is used as Schottky contact and gold contact as Ohmic contact to detect hydrogen as a gas sensor.

[0036] From the attached Figure 3 It can be seen from the curve that when the Sn concentration is 2.3×10 18 cm -3 The maximum response value is 89 at 25°C, which is very suitable for the safe detection of hydrogen.

[0037] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any modifications, equivalent substitutions and improvements made by any technician familiar with the technical field within the technical scope disclosed by the present invention and within the spirit and principle of the present invention should be covered by the protection scope of the present invention.

Claims

1. A method for preparing a Pd / α-Ga2O3 sensor for high-sensitivity hydrogen detection, characterized in that: The following steps are involved: Firstly, a 1-2 μm thick α-Ga2O3 layer is deposited on a c-plane sapphire substrate by using a mist chemical vapor deposition method; gallium acetylacetonate and pure oxygen are used as raw materials, and SnCl4·5H2O is doped in the raw materials, and the growth is carried out in a mist chemical vapor deposition device, and the growth temperature is set to 450-550°C; a Pd Schottky contact is deposited on the surface of the epitaxial layer by magnetron sputtering using a shadow mask, and the thickness of the Pd layer contact is 300-330nm, forming an MSM structure with a Schottky contact, and the wafer is cut into chips.

2. The method for preparing a Pd / α-Ga2O3 sensor for high-sensitivity hydrogen detection according to claim 1, characterized in that: The Sn donor concentration is 3.8×10 16 cm -3 ~2.3×10 18 cm -3 .

3. The method for preparing a Pd / α-Ga2O3 sensor for high-sensitivity hydrogen detection according to claim 2, characterized in that: The Sn donor concentration is 2.3×10 18 cm -3 .

4. A Pd / α-Ga2O3 sensor prepared by the preparation method according to any one of claims 1 to 3.

5. Application of the Pd / α-Ga2O3 sensor according to claim 4 in hydrogen detection.

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