Progress towards high power thin film diamond transistors

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. Schottky diodes and metal-semiconductor FETs (MESFETs) have been fabricated using this approach which display excellent 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 may be capable of operation at power levels up to 10 W mm(-1), implying that thin film diamond may, after all, be an interesting material for power applications. (C) 1999 Elsevier Science S.A. All rights reserved.