Gas sensor and manufacturing method thereof

[0029] Example 1

[0030] This embodiment provides a method of fabricating a gas sensor, such as figure 1 As shown, the method of making includes:

[0031] Step S1 provides a substrate 1 made of a semiconductor material containing a metal element. Preferably, the substrate 1 is made of a Algainn material.

[0032] In step S2, the substrate 1 is partially oxidized, so that the portion of the oxidized form is a gas sensitive portion 11. Specifically, a method of oxidizing a portion of the substrate 1 may employ a strong oxidant reaction process or an ultraviolet optical assist oxidation process. Wherein, the specific range of the portion can be determined according to the actual situation, for example: Figure 2A As shown, the portion may occupy the entire area of ​​the substrate 1, or Figure 2b As shown, the portion may occupy a partial area of ​​the substrate 1.

[0033] The substrate 1 of the gas sensor produced by the production method provided in the present embodiment is integrally formed with the gas sensitive portion 11, so that the substrate 1 and the gas sensitive portion 11 are not bonded, so even if Use in harsh environments. Since the gas sensitive portion 11 of the present embodiment is actually a portion that is oxidized by the substrate 1, the gas sensitive portion 11 is not easily disappeared, thereby ensuring stable gas sensitivity of the gas sensor.

[0034] Further, the substrate 1 of the present embodiment is made of an AlGainn material, so that the mechanical properties and chemical stability of the gas sensor can be improved.

[0035] It should be noted that the particular material of the substrate 1 in this embodiment can also be replaced with one of AlGaN, Aln, GaN, Gainn, AlINn.

[0036] Further, the method of producing the gas sensor of the present embodiment further includes the step of forming the first electrode 21 and the second electrode 22. Wherein, the first electrode 21 and the second electrode 22 are formed on the gas sensitive portion 11; or the first electrode 21 is formed on the gas sensitive portion 11, the second electrode 22 forms On the substrate 1 other than the gas sensitive portion 11. When the second electrode 22 is formed on the substrate 1 other than the gas sensitive portion 11, heterojunction is formed between the gas sensitive portion 11 and the substrate 1, thereby facilitating improving gas sensors. Sensitivity.

[0037] The working principle of the gas sensor of this embodiment is as follows:

[0038] In a general air environment, the oxygen molecules in the air are adsorbed on the gas sensitive portion surface of the gas sensor, and the oxygen molecule deprives the electrons in the gas sensitive portion, thereby converting into an oxygen negative ion (O -. In this process, the heterogeneous junction of the gas sensor is depleted, resulting in an increase in the resistance of the gas sensor. Indicine hydrogen sulfide (H 2 When the contaminated gas is contaminated, the hydrogen sulfide gas reacts with the oxygen negative ions described above, and the electron is released into the exhaust layer of the heterojunction of the gas sensor, thereby reducing the resistance of the gas sensor and improves the gas sensor. The increase in conductivity is generated by a change in current signal, thereby detecting hydrogen sulfide gases. This change in current signal will become more apparent as the concentration of hydrogen sulfide gas or oxygen negative ions become more obvious.

[0039] Example 2

[0040] Different from the first embodiment, in the production method of the present embodiment, the method further comprises: surface treatment of the substrate 1 of the substrate 1 to be oxidized, so that the The surface of the substrate has a microstructure of the surface of the portion of the oxidized portion. Among them, the specific form of the microstructure can be determined according to actual needs. Preferably, the microstructure may be a columnar structure or a blind hole structure arranged in an array.

[0041] In this embodiment, after the above steps, the gas sensitive portion 11 which is subsequently oxidized, and the microstructure can increase the surface area of ​​the gas sensitive portion 11, thereby increasing the gas sensitive portion 11. The contact area between the detecting gas can be improved in the sensitivity of the gas sensor.

[0042] Example 3

[0043] Unlike Example 1, in the production method of the present embodiment, the first electrode 21 and the second electrode 22 are formed, and further includes the substrate 1 other than the gas sensitive portion 11. The step of setting the heating unit 3 is provided.

[0044]Specifically, a paste layer 4 is formed on the substrate 1 other than the gas sensitive portion 11, and the adhesive layer 4 is formed, and the heating unit 3 is provided on the adhesive layer 4. The heating unit 3 is configured to adjust the temperature of the substrate 1 and the gas sensitive portion 11, so that the temperature of the gas sensitive portion 11 is close to the temperature of the surrounding gas to further improve the gas sensor. Detection sensitivity.