Thin film field effect transistor type gas sensor and preparation method thereof

Abstract

The invention discloses a thin film field effect transistor type gas sensor and a preparation method thereof. The sensor is a thin film field effect transistor with a bottom gate top contact type structure or a bottom gate bottom contact type structure. A thin film field effect transistor with a bottom grid top contact structure is taken as an example. The transistor comprises a substrate, a gateinsulating layer and a channel active layer from bottom to top. The channel active layer is a quantum dot thin film. A source electrode and a drain electrode are deposited above the substrate. A gateelectrode is further led out of the substrate. The internal composition, the structure, the overall process of the corresponding preparation method and the parameters during all steps of the preparation method of the thin film field effect transistor type gas sensor are improved. The quantum dot thin film serves as a channel active layer and a gas sensitive layer at the same time, and the gas response of multiple parameters is comprehensively regulated by utilizing the grid bias voltage. As a result, the prepared gas sensor is high in sensitivity, low in power consumption and high in selectivity. The effect of detecting low-concentration target gases, such as NO2 and H2S, is achieved.

Description

technical field [0001] The invention belongs to the technical field of gas sensors, and more specifically relates to a thin film field effect transistor type gas sensor and a preparation method thereof. layer thin film field effect transistor type (gas sensor. Background technique [0002] Traditional semiconductor gas sensors are usually based on layers of gas-sensitive materials (such as SnO 2 , ZnO, TiO 2 etc.) when in contact with gas, the resistance value changes to achieve the effect of gas detection. It has the characteristics of simple measurement method, high sensitivity, fast response, convenient operation, good portability, and low cost. However, this type of gas sensor generally adopts mature technology but Relatively large tubular or chip ceramic substrates, and commercial sensors must work at higher operating temperatures (200-600°C), resulting in higher power consumption, which reduces the portability and integration of sensors. Moreover, it also increases ...

AI Technical Summary

Problems solved by technology

In 2012, the Institute of Nanotechnology of the Karlsruhe Institute of Technology in Germany reported for the first time about the thin film field effect transistor of tin oxide, and the mobility of the device prepared by a simple spin-coating process can reach 0.13cm 2 V -1 the s -1 , the switching ratio is 85, and the threshold voltage is -1.9V, but at the same time, it also needs a higher gate voltage (above -50V) and source-drain voltage (-90V) and a harsh experimental environment (testing in an inert atmosphere) to fully realize High mobility; the harsh conditions required for high mobility also objectively limit the development of low-power gas sensing in practical applications, so this existing technology has not been used to detect gases

However, this high-mobility, all-quantum-dot FET needs to be inert (N 2 ) atmosphere preparation and testing can be realized, not suitable for use in real air atmosphere

[0008] In summary, the existing technologies can be summarized into two categories: 1) use quantum dots combined with traditional ceramic substrates to obtain a two-terminal device structure as a gas sensor; 2) use quantum dots combined with micro-nano technology to prepare three-terminal FET devices, and inert The electrical properties of semiconductors are tested in the environment, and it can be seen that quantum dot FETs are not used as gas sensors in the prior art (because the thin film field effect transistor TFT is a kind of field effect transistor FET, of course there is no quantum dot thin film in the prior art Field-effect transistor TFT is used for gas sensing), and there is no precedent at home and abroad to use quantum dot materials to prepare thin-film field-effect transistors and apply them to gas sensing in actual air atmospheres.

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