A gas sensor substrate, a method for preparing the same and applications thereof

Abstract

The application relates to a gas-sensitive sensor substrate, a preparation method and application thereof, and the gas-sensitive sensor substrate comprises a light source layer, a semiconductor substrate layer and a gas-sensitive sensing material layer which are sequentially stacked. The application introduces an in-situ light source layer into the gas-sensitive sensor substrate, realizes in-situ enhancement of the gas-sensitive sensor, makes the sensor have high sensitivity at low temperature, has high stability and good reproducibility, can improve the light utilization rate of the substrate, has better surface enhancement effect, can meet the gas-sensitive sensor with various requirements, and has simple preparation process and low cost.

Description

Technical Field

[0001] This invention relates to the field of sensor technology, and in particular to a gas-sensitive sensor substrate, its fabrication method, and its application. Background Technology

[0002] Metal-oxide-semiconductor (MOS) gas sensors have demonstrated powerful capabilities as ultra-sensitive and high-precision analytical tools in industrial monitoring, environmental analysis, and biomedicine. Currently, the biggest challenge for this technology in practical applications lies in the high operating temperature of the sensors. High operating temperatures lead to decreased material stability, limiting the application of this type of sensor. Although various active materials have been developed to improve low-temperature performance, extend device lifespan, and detect specific target gases, it remains difficult to obtain a gas sensor that simultaneously possesses high sensitivity, high stability, and low cost at low temperatures.

[0003] CN105842290A discloses a vacuum in-situ composite method for an inorganic-organic composite gas sensor to improve its performance. The method involves heat-treating a porous oxide semiconductor nanosolid in a high vacuum to thoroughly remove adsorbed gas molecules and other impurities from the sample surface, resulting in a clean surface. Subsequently, while maintaining a high vacuum, an organic semiconductor solution is introduced to immerse the porous oxide semiconductor nanosolid, allowing the organic semiconductor molecules to fully contact and bond with the clean solid surface, thus forming an inorganic-organic composite semiconductor gas-sensitive material while modifying the surface. The gas sensor provided by this invention operates at 100℃; however, higher temperatures degrade material stability and affect device lifespan.

[0004] CN110231372A discloses a gas sensor for acetone detection and its preparation method. The gas sensor comprises a gas sensor body coated with a tungsten trioxide-titanium carbide composite material film. This invention is the first to apply titanium carbide to a gas sensor. By coating a traditional gas sensor with a tungsten trioxide-titanium carbide composite material film, the gas-sensing performance of traditional tungsten trioxide for acetone is greatly enhanced, improving selectivity and resulting in high sensitivity, up to 25, which is up to 5 times higher than that of traditional tungsten trioxide gas sensors. It can detect even at a gas concentration of 2 ppm, and exhibits fast response speed and good repeatability. However, the operating temperature of the gas sensor provided by this invention is as high as 300℃, which seriously affects the device lifespan.

[0005] Therefore, there is an urgent need in this field to develop a gas sensor that can have high sensitivity at low temperatures. Summary of the Invention

[0006] To address the shortcomings of existing technologies, one of the objectives of this invention is to provide a gas-sensitive sensor substrate, particularly an in-situ light-enhanced gas-sensitive sensor substrate. The gas-sensitive sensor assembled from the gas-sensitive sensor substrate exhibits high sensitivity, high stability, low energy consumption, and high reproducibility at low temperatures, and its fabrication process is simple and inexpensive.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] The present invention provides a gas-sensitive sensor substrate, which includes a light source layer, a semiconductor substrate layer and a gas-sensitive sensing material layer stacked sequentially.

[0009] This invention provides a novel gas sensor substrate by introducing an in-situ light source layer into the substrate to achieve in-situ enhancement of the gas sensor. This enables the sensor to maintain high sensitivity, high stability, and good reproducibility even at low temperatures (10-100℃), while also improving the light utilization rate of the substrate and enhancing the surface enhancement effect. This allows for a gas sensor that can meet various needs, and the fabrication process is simple and low-cost.

[0010] Preferably, the light source layer is a light-emitting diode (LED) light source layer. An LED is an energy-saving light-emitting device with good wavelength selectivity. It can replace heating chips to improve the sensing efficiency of gas sensors, reduce operating temperature and energy consumption, and maintain the stability and lifespan of the gas-sensitive material.

[0011] Preferably, the light-emitting diode light source layer includes a sapphire substrate stacked thereon, and P-type semiconductors and N-type semiconductors disposed on the sapphire substrate. The interface between the P-type semiconductor and the N-type semiconductor forms a space charge region, referred to as a PN junction.

[0012] Preferably, the emission wavelength of the light source layer is 254-405nm, such as 260nm, 270nm, 280nm, 290nm, 300nm, 310nm, 320nm, 330nm, 340nm, 350nm, 360nm, 370nm, 380nm, 390nm, 400nm, etc.

[0013] Preferably, the material of the semiconductor substrate layer includes any one or at least a combination of gallium nitride, aluminum nitride, or indium nitride.

[0014] Preferably, the gallium nitride is n-type gallium nitride.

[0015] Preferably, the gas-sensitive sensing material layer is made of metal oxide, preferably any one or at least a combination of two of zinc oxide, cobalt oxide, or cerium oxide.

[0016] Preferably, both the semiconductor substrate layer and the gas-sensitive sensing material layer have a micropore array structure.

[0017] The present invention preferably has a micropore array structure in the semiconductor substrate layer and the gas-sensitive sensing material layer. The microstructure array is composed of multiple microstructure arrays arranged together. Compared with a two-dimensional substrate, the present invention can make the substrate have more active "hot spots" and a larger specific surface area by introducing a micropore array structure. At the same time, the micropore array structure also provides a good channel for light to enter, thereby further improving the surface enhancement effect, stability, sensitivity and reproducibility of the gas-sensitive sensor substrate.

[0018] Preferably, the semiconductor substrate layer has the same micropore array structure as the gas-sensitive sensing material layer.

[0019] Preferably, the micropores in the micropore array structure are hexagonal or circular in shape.

[0020] Preferably, the pore size of the micropores in the micropore array structure is 50-100 nm, more preferably 50-80 nm, such as 55 nm, 60 nm, 65 nm, 70 nm, 75 nm, 80 nm, 85 nm, 90 nm, 95 nm, etc. Here, the pore size refers to the straight-line distance between the two farthest points in the pore, i.e., the maximum pore size.

[0021] Preferably, the gas-sensitive sensing material layer is disposed directly on the semiconductor substrate layer and does not contact the light source layer.

[0022] Preferably, the thickness of the light source layer is 3-4 μm, such as 3.1 μm, 3.2 μm, 3.3 μm, 3.4 μm, 3.5 μm, 3.6 μm, 3.7 μm, 3.8 μm, 3.9 μm, etc., and preferably 3.2 μm.

[0023] Preferably, the thickness of the semiconductor substrate layer is 3-7 μm, such as 3.5 μm, 4 μm, 4.5 μm, 5 μm, 5.5 μm, 6 μm, 6.5 μm, etc., and preferably 5 μm.

[0024] Preferably, the thickness of the gas-sensitive sensing material layer is 10-60 nm, such as 20 nm, 30 nm, 40 nm, 50 nm, etc.

[0025] A second objective of this invention is to provide a method for fabricating the gas-sensitive sensor substrate described in the first objective, the method comprising the following steps:

[0026] (1) Semiconductor material is grown by vapor phase epitaxy on the light source layer to obtain a semiconductor substrate layer;

[0027] (2) A metal oxide is grown in situ on the semiconductor substrate to form a gas-sensitive sensing material layer, thereby obtaining the gas-sensitive sensor substrate.

[0028] The preparation method provided by the present invention forms a semiconductor substrate layer and a gas-sensitive sensing material layer in situ, and the process is simple and easy to mass-produce.

[0029] Furthermore, compared to the existing method of mounting the prepared gas-sensitive sensor chip onto an external light source, the in-situ growth method of metal oxides in this invention avoids the use of an external light source, thereby further improving the utilization rate of the light source. Under the same enhanced light source, it can further improve the surface enhancement effect, stability, sensitivity, and reproducibility.

[0030] Preferably, in step (1), the semiconductor material includes any one or at least a combination of two of gallium nitride, aluminum nitride, or indium nitride.

[0031] Preferably, in step (1), the gas used for vapor phase epitaxial growth includes a combination of ammonia, GaCl, hydrogen, and nitrogen.

[0032] Preferably, step (1) further includes: ultrasonically cleaning the obtained semiconductor substrate layer and then drying it with N2.

[0033] Preferably, the ultrasonic cleaning is performed sequentially in aqua regia, acetone, ethanol, and deionized water.

[0034] Preferably, the ultrasonic cleaning time is 20-50 minutes, such as 25 minutes, 30 minutes, 35 minutes, 40 minutes, 45 minutes, etc.

[0035] Preferably, step (1') is performed after step (1): the semiconductor substrate obtained in step (1) is etched to obtain a semiconductor substrate with a micro-hole array structure.

[0036] Preferably, in step (1'), the etching method includes electrochemical etching or photoelectrochemical wet etching.

[0037] Preferably, the etching solution for the photoelectrochemical wet etching includes an ionic liquid, preferably 1-ethyl-3-methylimidazolium trifluoromethanesulfonate.

[0038] Preferably, the light source for the photoelectrochemical wet etching includes a xenon lamp.

[0039] Preferably, the power of the xenon lamp is 200-400W, such as 220W, 240W, 260W, 280W, 300W, 320W, 340W, 360W, 380W, etc.

[0040] Preferably, the pressure of the photoelectrochemical wet etching is 4-6V, such as 4.2V, 4.4V, 4.6V, 4.8V, 5V, 5.2V, 5.4V, 5.6V, 5.8V, etc.

[0041] Preferably, the photoelectrochemical wet etching time is 10-30 min, such as 12 min, 14 min, 16 min, 18 min, 20 min, 22 min, 24 min, 26 min, 28 min, etc.

[0042] Preferably, after the etching, the semiconductor substrate is cleaned with deionized water and then dried with N2 to obtain a semiconductor substrate with a micropore array structure.

[0043] Preferably, in step (2), in-situ growth is performed on the micro-pore array of the semiconductor substrate. That is, growth is performed on the micro-pore array of the semiconductor substrate, and no growth is performed in the region of the micropores.

[0044] Preferably, in step (2), the in-situ growth method includes any one of electrochemical deposition, chemical vapor deposition or organic salt pyrolysis, with electrochemical deposition being preferred.

[0045] Preferably, the raw material for the organic salt pyrolysis includes a metal salt solution, and more preferably, the metal cation in the metal salt includes Zn. 2+ Ce 3+ or Co 2+ Any one or at least two of them.

[0046] Preferably, the molar concentration of the metal salt in the metal salt solution is 0.3-0.8 mmol / L, such as 0.4 mmol / L, 0.5 mmol / L, 0.6 mmol / L, 0.7 mmol / L, etc., and preferably 0.5 mmol / L.

[0047] Preferably, the organic salt pyrolysis specifically includes: adding a metal salt solution dropwise onto the conductor substrate, heating and holding it in a tube furnace to obtain the gas-sensitive sensing material layer.

[0048] Preferably, the heating gas flow in the tubular furnace comprises a mixture of oxygen and nitrogen, and more preferably nitrogen containing 5% oxygen by volume.

[0049] Preferably, in the pyrolysis of the organic salt, the heating rate is 8-12℃ / min, such as 8.5℃ / min, 9℃ / min, 9.5℃ / min, 10℃ / min, 10.5℃ / min, 11℃ / min, 11.5℃ / min, etc., and preferably 10℃ / min.

[0050] Preferably, the holding temperature during the pyrolysis of the organic salt is 300-400℃, such as 310℃, 320℃, 330℃, 340℃, 350℃, 360℃, 370℃, 380℃, 390℃, etc., with 350℃ being the most preferred.

[0051] Preferably, the heat preservation time in the organic salt pyrolysis is 1-3 hours, such as 1.2 hours, 1.4 hours, 1.6 hours, 1.8 hours, 2 hours, 2.2 hours, 2.4 hours, 2.6 hours, 2.8 hours, etc., with 2 hours being the most preferred.

[0052] Preferably, the deposition solution for electrochemical deposition contains a metal salt, and more preferably, the metal cation in the metal salt includes Zn. 2+ Ce 3+ or Co 2+ Any one or at least two of them.

[0053] Preferably, the deposition solution of the electrochemical deposition also contains CH3COONH4.

[0054] Preferably, the molar concentration of the metal oxide salt in the sediment is 4-6 mmol / L, more preferably 5 mmol / L, such as 4.2 mmol / L, 4.4 mmol / L, 4.6 mmol / L, 4.8 mmol / L, 5 mmol / L, 5.2 mmol / L, 5.4 mmol / L, 5.6 mmol / L, 5.8 mmol / L, etc.

[0055] Preferably, the molar concentration of CH3COONH4 in the sediment is 0.5-1 mmol / L, for example, 0.6 mmol / L, 0.7 mmol / L, 0.8 mmol / L, 0.9 mmol / L, etc.

[0056] Preferably, the working electrode, counter electrode, and reference electrode of the electrochemical deposition are the semiconductor substrate, the platinum sheet, and the silver / silver chloride electrode, respectively.

[0057] Preferably, the electrochemical deposition temperature is 20-30℃, such as 21℃, 22℃, 23℃, 24℃, 25℃, 26℃, 27℃, 28℃, 29℃, etc.

[0058] Preferably, the electrochemical deposition time is 20-40 min, more preferably 22 min, 24 min, 26 min, 28 min, 30 min, 32 min, 34 min, 36 min, 38 min, etc.

[0059] Preferably, the open-circuit voltage of the electrochemical deposition is -2V to -1V, such as -1.9V, -1.8V, -1.7V, -1.6V, -1.5V, -1.4V, -1.3V, -1.2V, -1.1V, etc., with -1.2V being the most preferred.

[0060] Preferably, the current for electrochemical deposition is 0.05-0.2mA, such as 0.06mA, 0.08mA, 0.1mA, 0.12mA, 0.14mA, 0.16mA, 0.18mA, etc., and preferably 0.1mA.

[0061] Preferably, the number of cyclic voltammetric deposition cycles in the electrochemical deposition is 6-10 cycles, such as 7 cycles, 8 cycles, 9 cycles, etc., with 7 cycles being the most preferred.

[0062] Preferably, step (2) further includes: performing an annealing treatment after the electrochemical deposition. After annealing, the metal hydroxide is converted into an oxide, for example, zinc hydroxide is converted into zinc oxide, and cerium hydroxide is converted into cerium dioxide.

[0063] Preferably, the annealing process specifically includes: using pure air as the annealing atmosphere, heating, and holding at that temperature to obtain the gas-sensitive sensing material layer.

[0064] Preferably, in the annealing process, the heating rate is 8-12℃ / min, such as 8.5℃ / min, 9℃ / min, 9.5℃ / min, 10℃ / min, 10.5℃ / min, 11℃ / min, 11.5℃ / min, etc., and preferably 10℃ / min.

[0065] Preferably, the holding temperature in the annealing process is 300-500℃, such as 320℃, 340℃, 360℃, 380℃, 400℃, 420℃, 440℃, 460℃, 480℃, etc., with 400℃ being the most preferred.

[0066] Preferably, the holding time in the annealing process is 1-3 hours, such as 1.2 hours, 1.4 hours, 1.6 hours, 1.8 hours, 2 hours, 2.2 hours, 2.4 hours, 2.6 hours, 2.8 hours, etc., with 2 hours being the most preferred.

[0067] Preferably, the preparation method specifically includes the following steps:

[0068] (1) Gallium nitride is grown by vapor phase epitaxy on the light-emitting diode light source layer to obtain a semiconductor substrate layer;

[0069] (1') The semiconductor substrate obtained in step (1) is irradiated with a 200-400W xenon lamp and subjected to photoelectrochemical wet etching at a voltage of 4-6V to obtain a semiconductor substrate with a micropore array structure.

[0070] (2) On the micro-pore array of the semiconductor substrate, metal oxide is grown in situ to obtain the gas sensor substrate.

[0071] A third objective of this invention is to provide a gas sensor, which includes the gas sensor substrate described in one objective.

[0072] Preferably, the gas sensor further includes a sensor circuit.

[0073] The fourth objective of this invention is to provide an application of the gas-sensitive sensor substrate described in the first objective or the gas-sensitive sensor described in the third objective in industrial and agricultural safety analysis, environmental analysis, or biomedical analysis.

[0074] Compared with the prior art, the present invention has the following beneficial effects:

[0075] This invention provides a novel gas-sensitive sensor substrate by introducing an in-situ light source layer into the substrate to achieve in-situ enhancement of the gas-sensitive sensor. This enables the sensor to maintain high sensitivity, high stability, and good reproducibility even at low temperatures. It also improves the light utilization rate of the substrate and enhances the surface enhancement effect. This allows for a gas-sensitive sensor that can meet various needs, and the fabrication process is simple and low-cost. Attached Figure Description

[0076] Figure 1 This is a schematic diagram of the structure of the light-emitting diode light source layer and the unetched semiconductor substrate layer in a specific embodiment of the present invention.

[0077] Figure 2 This is a schematic diagram of the structure of the light-emitting diode light source layer and the semiconductor substrate layer with a micro-pore array structure in a specific embodiment of the present invention.

[0078] Figure 3 This is a schematic diagram of the structure of the gas-sensitive sensor substrate in a specific embodiment of the present invention.

[0079] Figure 4 This is a process flow diagram of the fabrication process of the gas-sensitive sensor substrate in a specific embodiment of the present invention.

[0080] Figure 5 This is a diagram of an apparatus for preparing a semiconductor substrate with a micropore array structure by photoelectrochemical etching according to a specific embodiment of the present invention.

[0081] Figure 6 This is a diagram of a device for electrochemically depositing a gas-sensitive material layer with a microporous array structure, according to a specific embodiment of the present invention.

[0082] Among them, 1-light-emitting diode light source layer, 2-unetched semiconductor substrate layer, 3-semiconductor substrate layer with micropore array structure, and 4-gas-sensitive sensing material layer with micropore array structure. Detailed Implementation

[0083] To facilitate understanding of the present invention, the following embodiments are provided. Those skilled in the art should understand that these embodiments are merely illustrative and should not be construed as limiting the scope of the invention.

[0084] Example 1

[0085] This embodiment provides a gas-sensitive sensor substrate, such as... Figure 3 As shown, it includes a light-emitting diode light source layer 1 (emitting light wavelength of 365nm and thickness of 3.2μm), a semiconductor substrate layer 3 (gallium nitride, thickness of 5μm) with a micropore array structure, and a gas-sensitive sensing material layer 4 (zinc oxide, thickness of 30nm) with a micropore array structure. The micropore array structure of the semiconductor substrate layer and the gas-sensitive sensing material layer is the same, and the micropores in the micropore array structure are hexagonal in shape and have a diameter of 80nm.

[0086] The fabrication method of the above-mentioned gas sensor substrate is as follows (the fabrication process is as follows). Figure 4 As shown):

[0087] (1) A gallium nitride semiconductor substrate layer 2 (e.g., ...) is obtained by hydride vapor phase epitaxy growth (the vapor phase consists of ammonia, GaCl, hydrogen, and nitrogen) at the top of the light-emitting diode light source layer 1. Figure 1 (as shown);

[0088] The semiconductor substrate 2 was immersed in aqua regia, acetone, ethanol, and deionized water for ultrasonic cleaning for 10 minutes each (this time is the cleaning time in each solvent). After cleaning, the semiconductor substrate 2 was dried with N2 and set aside for later use.

[0089] (2) Figure 5 As shown, the semiconductor substrate layer 2 obtained in the above steps was immersed in an etching solution for photoelectrochemical etching. The etchant used was the ionic liquid [Emim]OTF (1-ethyl-3-methylimidazolium trifluoromethanesulfonate), the xenon lamp power was 300W, the etching voltage was 5V, and the etching time was 20min.

[0090] After etching, the substrate is rinsed with deionized water and dried with N2 to obtain a semiconductor substrate layer 3 with a micropore array structure (e.g., Figure 2 (As shown).

[0091] (3) Figure 6As shown, a semiconductor substrate 3 with a microporous array structure was used as the working electrode, a platinum sheet as the counter electrode, a silver / silver chloride (salt bridge solution of 3M KCl) electrode as the reference electrode, and a mixed solution of Zn(NO3)2 (5mmol / L) and CH3COONH4 (1mmol / L) as the electrolyte. Electrodeposition was performed at -1.2V for 30min to obtain a zinc hydroxide nanolayer.

[0092] In a tube furnace, pure air was used as the annealing atmosphere, and the temperature was increased to 400℃ at a rate of 10℃ / min and held for 2 hours to anneal the zinc hydroxide nanolayer, forming a zinc oxide gas-sensitive sensing material layer 4 with a microporous array structure. The layer was then rinsed with deionized water and dried with N2 to obtain the gas-sensitive sensor substrate (e.g., ...). Figure 3 (As shown).

[0093] Example 2

[0094] The difference from Example 1 is that the gas-sensitive material layer with microporous array structure is cobalt tetroxide. Step (3) includes: adding 0.5 mmol / L cobalt acetate solution dropwise onto the semiconductor substrate layer 3 with microporous array structure obtained in step (2) and drying it, adding a total of 20 mL; transferring the semiconductor substrate layer 3 with microporous array structure to a tube furnace for heating, wherein the heating gas flow is nitrogen gas containing 5% oxygen by volume, the heating rate is 10℃ / min, the holding temperature is 350℃, and the holding time is 2h, to obtain the cobalt tetroxide gas-sensitive material layer 4 with microporous array structure; rinsing it with deionized water and drying it with N2 to obtain the gas-sensitive sensor substrate (e.g., Figure 3 (As shown).

[0095] Example 3

[0096] The difference from Example 1 is that the gas-sensitive sensing material layer with the microporous array structure is made of cerium oxide, and step (3) includes: Figure 6 As shown, a semiconductor substrate 3 with a microporous array structure was used as the working electrode, a platinum sheet as the counter electrode, a silver / silver chloride (salt bridge solution of 3M KCl) electrode as the reference electrode, and a mixed solution of Ce(NO3)3 (5mmol / L) and CH3COONH4 (1mmol / L) as the electrolyte. Electrodeposition was carried out at a current of 0.1mA for 30min to obtain a cerium hydroxide nanolayer.

[0097] In a tube furnace, pure air was used as the annealing atmosphere, and the temperature was increased to 500℃ at a rate of 10℃ / min and held for 2 hours to anneal the zinc hydroxide nanolayer, forming a zinc oxide gas-sensitive sensing material layer 4 with a microporous array structure. The layer was then rinsed with deionized water and dried with N2 to obtain the gas-sensitive sensor substrate (e.g., ...). Figure 3 (As shown).

[0098] Example 4

[0099] The difference from Example 1 is that the gas-sensitive sensing material layer with the microporous array structure is made of cerium oxide and zinc oxide, and the cerium oxide and zinc oxide are stacked. Step (3) includes: Figure 6 As shown, a semiconductor substrate 3 with a microporous array structure was used as the working electrode, a platinum sheet as the counter electrode, and a silver / silver chloride (salt bridge solution of 3M KCl) electrode as the reference electrode. A mixed solution of Ce(NO3)3 (5mmol / L) and CH3COONH4 (1mmol / L) was used as the first electrolyte. A first electrodeposition was performed at a current of 0.1mA for 30min. Subsequently, a mixed solution of Zn(NO3)2 (5mmol / L) and CH3COONH4 (1mmol / L) was used as the second electrolyte. A second electrodeposition was performed at a current of 0.1mA for 30min to obtain a layered bimetallic hydroxide nanolayer (cerium hydroxide and zinc hydroxide).

[0100] In a tube furnace, pure air was used as the annealing atmosphere, and the temperature was increased to 500℃ at a rate of 10℃ / min and held for 2 hours to anneal the layered bimetallic hydroxide nanolayer, forming a CeO2@ZnO gas-sensitive material layer 4 with a microporous array structure. The layer was then rinsed with deionized water and dried with N2 to obtain the gas-sensitive sensor substrate (e.g., ...). Figure 3 (As shown).

[0101] Example 5

[0102] This embodiment provides a gas-sensitive sensor substrate, such as... Figure 3 As shown, it includes a light-emitting diode light source layer 1 (emitting light wavelength of 254nm and thickness of 3.2μm), a semiconductor substrate layer 3 (gallium nitride, thickness of 3μm) with a micropore array structure, and a gas-sensitive sensing material layer 4 (zinc oxide, thickness of 3nm) with a micropore array structure. The micropore array structure of the semiconductor substrate layer and the gas-sensitive sensing material layer is the same, and the micropores in the micropore array structure are hexagonal in shape and have a diameter of 50nm.

[0103] The fabrication method of the above-mentioned gas sensor substrate is as follows (the fabrication process is as follows). Figure 4 As shown):

[0104] (1) A gallium nitride semiconductor substrate layer 2 (e.g., ...) is obtained by hydride vapor phase epitaxy growth (same as in Example 1) at the top of the light-emitting diode light source layer 1. Figure 1 (as shown);

[0105] Semiconductor substrate 2 was immersed in aqua regia, acetone, ethanol, and deionized water for ultrasonic cleaning for 20 minutes each. After cleaning, semiconductor substrate 2 was dried with N2 and set aside for later use.

[0106] (2) Figure 5 As shown, the semiconductor substrate layer 2 obtained in the above steps was immersed in an etching solution for photoelectrochemical etching. The etchant used was the ionic liquid [Emim]OTF (1-ethyl-3-methylimidazolium trifluoromethanesulfonate), the xenon lamp power was 200W, the etching voltage was 4V, and the etching time was 10min.

[0107] After etching, the substrate is rinsed with deionized water and dried with N2 to obtain a semiconductor substrate layer 3 with a micropore array structure (e.g., Figure 2 (As shown).

[0108] (3) Figure 6 As shown, a semiconductor substrate 3 with a microporous array structure was used as the working electrode, a platinum sheet as the counter electrode, a silver / silver chloride (salt bridge solution of 3M KCl) electrode as the reference electrode, and a mixed solution of Zn(NO3)2 (4mmol / L) and CH3COONH4 (0.5mmol / L) as the electrolyte. Electrodeposition was performed at -1V for 20min to obtain a zinc hydroxide nanolayer.

[0109] In a tube furnace, pure air was used as the annealing atmosphere, and the temperature was increased to 300°C at a rate of 8°C / min and held for 3 hours to anneal the zinc hydroxide nanolayer, forming a zinc oxide gas-sensitive sensing material layer 4 with a microporous array structure. The layer was then rinsed with deionized water and dried with N2 to obtain the gas-sensitive sensor substrate (e.g., ...). Figure 3 (As shown).

[0110] Example 6

[0111] This embodiment provides a gas-sensitive sensor substrate, such as... Figure 3 As shown, it includes a light-emitting diode light source layer 1 (emitting light wavelength of 405nm and thickness of 3.2μm), a semiconductor substrate layer 3 (gallium nitride, thickness of 7μm) with a micropore array structure, and a gas-sensitive sensing material layer 4 (zinc oxide, thickness of 35nm) with a micropore array structure. The micropore array structure of the semiconductor substrate layer and the gas-sensitive sensing material layer is the same, and the micropores in the micropore array structure are hexagonal in shape and have a diameter of 100nm.

[0112] The fabrication method of the above-mentioned gas sensor substrate is as follows (the fabrication process is as follows). Figure 4 As shown):

[0113] (1) A gallium nitride semiconductor substrate layer 2 (e.g., ...) is obtained by hydride vapor phase epitaxy growth (same as in Example 1) at the top of the light-emitting diode light source layer 1. Figure 1 (as shown);

[0114] Semiconductor substrate 2 was immersed in aqua regia, acetone, ethanol, and deionized water for ultrasonic cleaning for 20 minutes each. After cleaning, semiconductor substrate 2 was dried with N2 and set aside for later use.

[0115] (2) Figure 5 As shown, the semiconductor substrate layer 2 obtained in the above steps was immersed in an etching solution for photoelectrochemical etching. The etchant used was the ionic liquid [Emim]OTF (1-ethyl-3-methylimidazolium trifluoromethanesulfonate), the xenon lamp power was 400W, the etching voltage was 6V, and the etching time was 30min.

[0116] After etching, the substrate is rinsed with deionized water and dried with N2 to obtain a semiconductor substrate layer 3 with a micropore array structure (e.g., Figure 2 (As shown).

[0117] (3) Figure 6 As shown, a semiconductor substrate 3 with a microporous array structure was used as the working electrode, a platinum sheet as the counter electrode, a silver / silver chloride (salt bridge solution of 3M KCl) electrode as the reference electrode, and a mixed solution of Zn(NO3)2 (6mmol / L) and CH3COONH4 (1mmol / L) as the electrolyte. Electrodeposition was performed at -2V for 30min to obtain a zinc hydroxide nanolayer.

[0118] In a tube furnace, pure air was used as the annealing atmosphere, and the temperature was increased to 500℃ at a rate of 12℃ / min and held for 1 hour to anneal the zinc hydroxide nanolayer, forming a zinc oxide gas-sensitive sensing material layer 4 with a microporous array structure. The layer was then rinsed with deionized water and dried with N2 to obtain the gas-sensitive sensor substrate (e.g., ...). Figure 3 (As shown).

[0119] Example 7

[0120] The difference from Example 1 is that step (2) is not performed, and step (3) involves in-situ deposition of nano-zinc oxide on gallium nitride semiconductor substrate 2 as a gas-sensitive sensing material layer (without a micropore array structure).

[0121] Example 8

[0122] The difference from Example 1 is that step (3) does not use the in-situ deposition method. Specifically, a nano zinc oxide dispersion (≤50nm, 40wt.%, isopropanol as the dispersion solution) is dropped onto the semiconductor substrate layer 3 with a microporous array structure obtained in step (2) and dried. A total of 0.2mL is dropped on. The semiconductor substrate layer 3 with a microporous array structure is then transferred to an oven for heating and heat preservation at 60℃ for 4h, resulting in a non-in-situ zinc oxide gas-sensitive sensing material layer 4 with a microporous array structure, thus obtaining the gas-sensitive sensor substrate (e.g., ...). Figure 3(As shown).

[0123] Comparative Example 1

[0124] This comparative example provides a gas-sensitive sensor substrate, which differs from Example 1 only in that it does not include a light-emitting diode light source layer.

[0125] The only difference between the preparation method and Example 1 is that, in step (1), a gallium nitride semiconductor substrate layer 2 is grown on a sapphire substrate.

[0126] Performance testing:

[0127] The following performance tests were performed on the gas sensor substrates provided in the embodiments and comparative examples:

[0128] Place the gas sensor in a gas testing apparatus and measure the resistance of the gas-sensitive component using a source meter. Introduce either dry air or a 50 ppm ethanol flow (dry air as the carrier gas) to change the resistance of the gas-sensitive component. Record the stable resistance as R0 when dry air is introduced and the resistance as R when 50 ppm ethanol (dry air as the carrier gas) is introduced. g The sensitivity is defined as S = R0 / R g (Examples 1, 5-8, Comparative Example 1) or S=R g / R0 (Examples 2-4), response / recovery times are from R0 to R g or R g The time (in seconds) required to reach R0, and the number of days to maintain 90% sensitivity for stability.

[0129] In the embodiment, the gas sensor substrate is directly enhanced using an in-situ light source (performed at room temperature). In Comparative Example 1, the gas sensor substrate is enhanced using a 200μW ultraviolet LED lamp (temperature less than 100°C after irradiation) and by a chip heating method (heating temperature of 250°C).

[0130] The performance test results are shown in Figure 1.

[0131] Table 1

[0132]

[0133]

[0134] As shown in Table 1, the gas sensor substrate provided by this invention achieves high sensitivity, good stability, fast response and recovery rates, and good enhancement effect at room temperature. Specifically, the sensitivity can reach below 30, the response time can reach below 7 seconds, the recovery time can reach below 4 seconds, and the number of days to maintain 90% sensitivity can reach >60 days.

[0135] In Comparative Example 1, the sensor temperature reached 100°C under external irradiation, which affected the sensor's stability, thus reducing its lifespan, and also resulted in lower light utilization (compared to Example 1). Traditional chip heating methods also affect sensor stability and reduce its lifespan.

[0136] By comparing Examples 1 and 7, it can be seen that when the semiconductor substrate layer and the gas-sensitive sensing material layer have a micropore array structure (Example 1), compared with the two-dimensional substrate (Example 7), the overall performance of the gas-sensitive sensor substrate, including sensitivity, stability, response and recovery rate, can be further improved.

[0137] By comparing Examples 1 and 8, it can be seen that the in-situ deposition of the gas-sensitive sensing material layer (Example 1) can further improve the overall performance of sensitivity, stability, response and recovery rate compared to the method of non-in-situ deposition of the prepared metal oxide gas-sensitive sensing material on the substrate layer by coating method (Example 8).

[0138] The applicant declares that the detailed method of the present invention is illustrated by the above embodiments, but the present invention is not limited to the above detailed method, that is, it does not mean that the present invention must rely on the above detailed method to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A gas-sensitive sensor substrate, characterized in that, The gas-sensitive sensor substrate includes a light source layer, a semiconductor substrate layer, and a gas-sensitive sensing material layer stacked sequentially. Both the semiconductor substrate layer and the gas-sensitive sensing material layer have a microporous array structure; The gas-sensitive sensor substrate is prepared according to the following method: (1) Semiconductor material is grown by vapor phase epitaxy on the light source layer to obtain a semiconductor substrate layer; (2) A metal oxide is grown in situ on the semiconductor substrate to form a gas-sensitive sensing material layer, thereby obtaining the gas-sensitive sensor substrate.

2. The gas-sensitive sensor substrate according to claim 1, characterized in that, The light source layer is a light-emitting diode (LED) light source layer.

3. The gas-sensitive sensor substrate according to claim 1, characterized in that, The semiconductor substrate layer is made of any one or at least a combination of gallium nitride, aluminum nitride, or indium nitride.

4. The gas-sensitive sensor substrate according to claim 1, characterized in that, The gas-sensitive sensing material layer is made of metal oxides.

5. The gas-sensitive sensor substrate according to claim 4, characterized in that, The gas-sensitive sensing material layer is made of any one or at least a combination of two of zinc oxide, cobalt oxide, or cerium oxide.

6. The gas-sensitive sensor substrate according to claim 1, characterized in that, The semiconductor substrate layer has the same micropore array structure as the gas-sensitive sensing material layer.

7. The gas-sensitive sensor substrate according to claim 1, characterized in that, The micropores in the micropore array structure are hexagonal or circular in shape.

8. The gas-sensitive sensor substrate according to claim 1, characterized in that, The pore size of the micropores in the micropore array structure is 50-100 nm.

9. The gas-sensitive sensor substrate according to claim 8, characterized in that, The pore size of the micropores in the micropore array structure is 50-80 nm.

10. The gas-sensitive sensor substrate according to claim 1, characterized in that, The gas-sensitive sensing material layer is directly disposed on the semiconductor substrate layer and does not contact the light source layer.

11. The gas-sensitive sensor substrate according to claim 1, characterized in that, The thickness of the light source layer is 3-4 μm.

12. The gas-sensitive sensor substrate according to claim 11, characterized in that, The thickness of the light source layer is 3.2 μm.

13. The gas-sensitive sensor substrate according to claim 1, characterized in that, The thickness of the semiconductor substrate layer is 3-7 μm.

14. The gas-sensitive sensor substrate according to claim 13, characterized in that, The thickness of the semiconductor substrate is 5 μm.

15. The gas-sensitive sensor substrate according to claim 1, characterized in that, The thickness of the gas-sensitive sensing material layer is 10-60 nm.

16. A method for preparing a gas-sensitive sensor substrate according to any one of claims 1-15, characterized in that, The preparation method includes the following steps: (1) Semiconductor material is grown by vapor phase epitaxy on the light source layer to obtain a semiconductor substrate layer; (2) A metal oxide is grown in situ on the semiconductor substrate to form a gas-sensitive sensing material layer, thereby obtaining the gas-sensitive sensor substrate.

17. The preparation method according to claim 16, characterized in that, In step (1), the semiconductor material includes any one or at least a combination of two of gallium nitride, aluminum nitride, or indium nitride.

18. The preparation method according to claim 16, characterized in that, In step (1), the gas used for vapor phase epitaxial growth includes a combination of ammonia, GaCl, hydrogen, and nitrogen.

19. The preparation method according to claim 16, characterized in that, Step (1) also includes: ultrasonically cleaning the obtained semiconductor substrate layer and then drying it with N2.

20. The preparation method according to claim 19, characterized in that, The ultrasonic cleaning was performed sequentially in aqua regia, acetone, ethanol, and deionized water.

21. The preparation method according to claim 19, characterized in that, The ultrasonic cleaning time is 20-50 minutes.

22. The preparation method according to claim 16, characterized in that, Step (1') is performed after step (1): the semiconductor substrate obtained in step (1) is etched to obtain a semiconductor substrate with a micro-hole array structure.

23. The preparation method according to claim 22, characterized in that, In step (1'), the etching method includes electrochemical etching or photoelectrochemical wet etching.

24. The preparation method according to claim 23, characterized in that, The etching solution used in the photoelectrochemical wet etching process includes ionic liquids.

25. The preparation method according to claim 24, characterized in that, The etching solution used in the photoelectrochemical wet etching process is 1-ethyl-3-methylimidazolium trifluoromethanesulfonate.

26. The preparation method according to claim 23, characterized in that, The light source for the photoelectrochemical wet etching includes a xenon lamp.

27. The preparation method according to claim 26, characterized in that, The power of the xenon lamp is 200-400W.

28. The preparation method according to claim 23, characterized in that, The pressure for the photoelectrochemical wet etching is 4-6V.

29. The preparation method according to claim 23, characterized in that, The photoelectrochemical wet etching time is 10-30 min.

30. The preparation method according to claim 23, characterized in that, After the etching, the semiconductor substrate is cleaned with deionized water and then dried with N2 to obtain a semiconductor substrate with a micropore array structure.

31. The preparation method according to claim 16, characterized in that, In step (2), in-situ growth is performed on the micro-pore array of the semiconductor substrate.

32. The preparation method according to claim 16, characterized in that, In step (2), the in-situ growth method includes any one of electrochemical deposition, chemical vapor deposition, or organic salt pyrolysis.

33. The preparation method according to claim 32, characterized in that, The raw materials for the organic salt pyrolysis include metal salt solutions.

34. The preparation method according to claim 33, characterized in that, The metal cations in the metal salt include Zn. 2 + Ce 3+ or Co 2+ Any one or at least two of them.

35. The preparation method according to claim 33, characterized in that, The molar concentration of the metal salt in the metal salt solution is 0.3-0.8 mmol / L.

36. The preparation method according to claim 35, characterized in that, The molar concentration of the metal salt in the metal salt solution is 0.5 mmol / L.

37. The preparation method according to claim 32, characterized in that, The organic salt pyrolysis specifically includes: adding a metal salt solution dropwise onto the conductor substrate, heating and holding it in a tube furnace to obtain the gas-sensitive sensing material layer.

38. The preparation method according to claim 37, characterized in that, The heating gas flow in the tubular furnace includes a mixture of oxygen and nitrogen.

39. The preparation method according to claim 38, characterized in that, The heating gas flow in the tubular furnace is nitrogen gas containing 5% oxygen by volume.

40. The preparation method according to claim 32, characterized in that, In the pyrolysis of the organic salt, the heating rate is 8-12℃ / min.

41. The preparation method according to claim 32, characterized in that, During the pyrolysis of the organic salt, the holding temperature is 300-400℃.

42. The preparation method according to claim 32, characterized in that, In the pyrolysis of the organic salt, the holding time is 1-3 hours.

43. The preparation method according to claim 32, characterized in that, The deposition solution used in the electrochemical deposition contains metal salts.

44. The preparation method according to claim 43, characterized in that, The metal cations in the metal salt include Zn. 2 + Ce 3+ or Co 2+ Any one or at least two of them.

45. The preparation method according to claim 43, characterized in that, The deposition solution for the electrochemical deposition also contains CH3COONH4.

46. ​​The preparation method according to claim 43, characterized in that, In the deposition solution, the molar concentration of the metal oxide salt is 4-6 mmol / L.

47. The preparation method according to claim 45, characterized in that, The molar concentration of CH3COONH4 in the sediment is 0.5-1 mmol / L.

48. The preparation method according to claim 32, characterized in that, The working electrode, counter electrode, and reference electrode of the electrochemical deposition are the semiconductor substrate, platinum sheet, and silver / silver chloride electrode, respectively.

49. The preparation method according to claim 32, characterized in that, The electrochemical deposition temperature is 20-30℃.

50. The preparation method according to claim 32, characterized in that, The electrochemical deposition time is 20-40 min.

51. The preparation method according to claim 32, characterized in that, The open-circuit voltage of the electrochemical deposition is -2V to -1V.

52. The preparation method according to claim 32, characterized in that, The current for the electrochemical deposition is 0.05-0.2 mA.

53. The preparation method according to claim 32, characterized in that, The number of cyclic voltammetric deposition cycles for the electrochemical deposition is 6-10.

54. The preparation method according to claim 32, characterized in that, Step (2) further includes annealing after the electrochemical deposition.

55. The preparation method according to claim 54, characterized in that, The annealing process specifically includes: using pure air as the annealing atmosphere, heating, and holding at that temperature to obtain the gas-sensitive sensing material layer.

56. The preparation method according to claim 55, characterized in that, In the annealing process, the heating rate is 8-12℃ / min.

57. The preparation method according to claim 55, characterized in that, During the annealing process, the holding temperature is 300-500℃.

58. The preparation method according to claim 55, characterized in that, During the annealing process, the holding time is 1-3 hours.

59. A gas-sensitive sensor, characterized in that, The gas sensor comprises the gas sensor substrate according to any one of claims 1-15.

60. The application of a gas sensor substrate according to any one of claims 1-15 or the gas sensor according to claim 59 in industrial and agricultural safety analysis, environmental analysis or biomedical analysis.

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