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

摘要

The carbon monoxide (CO) gas sensing performances of Au/SnO_x/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 ℃ and -3 V bias, the diode exhibits a high ～546% to 100 ppm CO ambient, which is better than the reported SnO_2 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 (AH0) sensing reaction, temperature enhanced barrier height lowering (△Φ_B) and different generation rates of O~- and O_2~- in elevated temperature.