Current conduction mechanism and gas adsorption effects on device parameters of the Pt/SnO/sub x//diamond gas sensor

This paper presents the results from analysis and modeling of the gas sensing performance, current conduction and gas detection mechanisms, and adsorption effects on device parameters of a Pt/SnO/sub x//diamond-based gas sensor. The sensor is sensitive and demonstrates high, repeatable, and reproducible reaction. The sensor response in seconds to small concentrations of O/sub 2/, CO, and H/sub 2/ gases. The current conduction mechanism of the diamond-based CAIS (catalyst/adsorptive-oxide/intrinsic-diamond/semiconductor-diamond) diode was found to be dominated by space charge limited conduction in the forward bias region and tunneling in the reverse bias region, distinctively different from silicon based sensors. While gas adsorption causes a change in the barrier height and tunneling factor, no significant change was observed in the ideality factor over the temperature range investigated. The detection mechanism of the sensor is attributable to the change in occupancy ratio of the oxygen vacancies of the adsorptive oxide layer upon oxygen exposure, increasing the contact potential between adsorptive-oxide and intrinsic-diamond.