Possibility of Realizing a Gas Sensor Using Surface Conductive Layer on Diamond Films

The electrical surface resistance of diamond films deposited by the hot-filament chemical vapor deposition (CVD) method is measured in oxidizing and reducing atmospheres. The electrical surface resistance decreases in NO2, HCl and O3 gases. On the other hand, it increases in NH3 gas. The mechanism of change in electrical resistance is explained by the formation mechanism of a p-type surface conductive layer. The realization of a gas sensor will be discussed considering the experimentally obtained results.