Dependence of the Au/SnOx/n-LTPS/glass thin film MOS Schottky diode CO gas sensing performances on operating temperature

The carbon monoxide (CO) gas sensing performances of Au/SnOx/n-LTPS MOS Schottky diode depending on operating temperature were studied systematically. The n-LTPS is the excimer laser annealed n-type low temperature polysilicon film on glass substrate. The Schottky diode has a nicely sensing ability to CO gas, especially under a higher operating temperature. For example under 200 °C and −3 V bias, the diode exhibits a high ∼546% to 100 ppm CO ambient, which is better than the reported SnO2 based resistive type CO sensors of 100% and 37%, respectively on poly-alumina and glass substrates. Mechanisms of the higher temperature enhanced CO gas sensing performance were investigated and attributed to positive enthalpy (ΔHo) sensing reaction, temperature enhanced barrier height lowering (ΔΦB) and different generation rates of O− and O2- in elevated temperature.