High-performance devices from surface-conducting thin-film diamond

Early predictions that diamond would be a suitable material for high-performance high-power devices were not supported by the characteristics of diodes and field effect transistors (FETs) fabricated on boron doped (p-type) thin-film material. In this paper commercially accessible polycrystalline thin-film diamond has been turned p-type by the incorporation of near-surface hydrogen, a type of film often referred to as 'surface conducting'. Schottky diodes and metal-semiconductor FETs (MESFETs) have been fabricated using this approach which display unprecedented performance levels; diodes with a rectification ratio>10(6), leakage currents<1 nA, no indication of reverse-bias breakdown at 100 V and an ideality factor of 1.1 have been made. Simple MESFET structures that are capable of withstanding V-DS values of 100 V with low leakage and current saturation (pinch-off) characteristics have also been fabricated. Predictions based upon experiments performed on these devices suggest that optimised device structures will be capable of operation at power levels up to 20 W mm(-1) implying that thin-film diamond may after all be an interesting material for power applications. (C) 1999 Elsevier Science Ltd. All rights reserved.