PHOTOCONDUCTIVE PROPERTIES OF POLYCRYSTALLINE DIAMOND UNDER HIGH-ELECTRIC-FIELD STRENGTH

The photoconductive properties of a diamond opto-electronic switch mad e by chemical vapor deposition were investigated. A new configuration of the diamond gap was proposed to reduce the surface leakage current and avoid surface flashover. This technology made it possible to apply a static electric field with strengths up to 2 x 10(6) V cm(-1). The dependence of the mobility-lifetime product mu tau on the grain size w as measured for a wide range of electric fields. The mu tau value was found to be linearly proportional to the electric field. Larger grain size samples had larger mu tau values. The grain size dependence was a ttributed to the decrease in the mobility and lifetime inside the grai n. The sensitivity to UV light was also measured and was 0.3 A W-1 at 150 nm. This indicated that diamond films were applicable to UV photos ensors.