Dependence of NO2 Gas on Schottky Diode Capacitance Fabricated by Using Diamond Thin Films

Schottky barrier diode has been fabricated on the diamond film and its gas sensing characteristics in nitrogen dioxide (NO2) gas have been investigated. The Schottky structure was composed by using a p-type surface conductive layer, which was formed on the as-grown diamond film, with metal contacts. The capacitance-applied voltage (C-V), capacitance change rate for NO2 gas concentration and time response in NO2 gas atmosphere and in dry air were measured. The capacitance change rate in NO2 gas had a maximum between-1V and 0V of applied voltage. The reversible time response was obtained when the NO2 gas injection was repeated. It was also indicated that the capacitance change rate was increased as the gas concentration increased. From these results, it was found that the diamond Schottky diode using the p-type surface conductive layer could be applied to the NO2 gas sensor devices.