THICKNESS DEPENDENCE OF THE ELECTRICAL CHARACTERISTICS OF CHEMICAL-VAPOR-DEPOSITED DIAMOND FILMS

The electrical characteristics of chemically vapor deposited (CVD) dia mond films were measured as a function of film thickness. The samples studied were polycrystalline with the average grain size increasing fr om approximately 1 mu m on the substrate side to approximately 30 mu m on the growth surface for the thickest sample. Using time-resolved tr ansient photoconductivity and charged-particle induced conductivity, t he collection distance (d) that a free carrier drifts under the influe nce of an applied electric field was measured. Our data indicate that there is a gradient in the collection distance through the material. T his gradient in electrical properties has implications for electronic uses of CVD diamond.