Dependence of Oxidative Gas Reaction on Diamond p-Type Surface Conductive Layer Annealed with Hydrogen Gas

Abstract

To develop the gas sensing devices using diamond films, time dependence of the surface resistance on the diamond film surrounded by oxidative gas has been investigated. After the termination of the diamond films surface by oxygen atom, the samples were annealed by hydrogen gas from 10 to 90 minutes (by 10 minutes step) under 900°C. The time depending changes in the surface resistance were measured in NO₂ gas and N₂ gas atmospheres. Following results were obtained. That is, in NO₂ gas atmosphere, transient time response of surface resistance of respectively annealed samples showed the almost identical time dependences. On the other hand, in N₂ gas atmosphere, samples were indicated no remarkable changes in annealing effect. To seek the situation concerned with the termination of annealed samples, the surface hydrogen densities per unit area were measured by ERDA (Elastic Recoil Detection Analysis). From these results, change mechanism of surface resistance due to annealing effect by hydrogen gas was discussed qualitatively.