High Power and High Temperature Passive Application of CVD Diamond

Polycrystalline diamond films produced by Microwave Plasma Enhanced Chemical Vapor Deposition were investigated for use as dielectric material for advanced passive devices needed in pulsed power applications. CVD diamond films that were heat treated in air from 250°C to 450°C for 2hrs. had very steady dielectric constants, ranging from 5 to 6.5, and very low losses, less than 0.005, over 100 to 10⁶Hz at room temperature. Dielectric constants varied by less than 5% with temperature cycling to 500°C and losses remained very low (less than 0.01). Resistivities of CVD diamond heat treated in air were two to three orders of magnitude higher than the as-deposited samples. Breakdown strength, I-V and charge-discharge characteristics were also measured. Surface termination was examined to explain differences in the electrical performance of heat treated and as-deposited CVD diamond.