Review on Stability of Metal-oxide-semiconductor Gas Sensor

Stability of metal-oxide-semiconductor(MOS) gas sensor is the most challenging factor in gas sensor′s practical application.It is found that the main factors responsible for the instability of device include the change of grain size,neck width,micro-cracks,electrode,humidity and temperature.Grain growth and change of neck width reduce the contribution of depletion layer to the whole resistance change;micro-cracks lead to resistance drift and provide short pathways for moisture,oxygen,and sensing gases diffuse more deeply to the films;deterioration of electrode affects the contact resistance Rc between electrode and gas sensing material;the variation of humidity and temperature changes gas adsorption,desorption,reactivity and electron mobility,so it results in poor stability.Based on the mechanism analysis,corresponding methods to improve stability have been introduced.