Simulation of the Grain Size Effect in Gas-Sensitive SnO2 Thin Films Using the Oxygen Vacancy Gradient Distribution Model

다국어 초록 (Multilingual Abstract)

The model of gradient-distributed oxygen vacancies is utilized in simulatingthe grain size effects of gas-sensitive SnO2 thin films. The distribution profileof oxygen vacancies has a grain size effect and the profile gradient correlatespositively with the radius of the grains. The simulation results show that thegrain size is a fundamental factor dominating the gas-sensing properties ofthin films. The potential barrier height and resistivity have significant grainsize effects when m is between 0.1 and 0.5 nm−1. The size effects on sensorresponse to stimulant gases can be enhanced by increasing the value of m orthe absolute value of α. Two expressions are used to simulate the grain sizeeffect of the sensor response. The expressions act similarly when α < 0.2.
The simplified response provides a neat function to quantitatively explain thesensor performance on gases with low partial pressure. Although the accurate response is complicated, it is applicable to theentire concentration range. A small power-law exponent n is calculated from the accurate response expression when a high gasconcentration is employed, illustrating a “saturation effect” of the response.

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