Schottky contacts on single-crystal CVD diamond

In this paper, a comparison of Gold, Nickel and Aluminium Schottky diodes fabricated on high-quality, Single-Crystal CVD Diamond is presented. Different metals. such as Gold, Nickel and Aluminium, have been deposited on the oxidised surface of an intrinsic diamond layer to serve as Schottky contacts, in order to investigate the physical properties of the different metal-semiconductor interfaces. A Cr-layer, followed by a subsequent Au deposition was used to form the Ohmic back contact for the Au-Schottky diodes, whereas a Cr-layer followed by a Ni deposition formed the Ohmic contact for the Ni and Al-Schottky contacts. Contacts have been characterized using I-V measurements. The gold Schottky contacts exhibited reverse leakage currents as low as 0.01 mu A at a reverse voltage of -600V, rising to 10 mu A at 1 kV (without any periphery protection). Nickel and Aluminium contacts exhibited lower reverse leakage currents and higher average breakdown voltages, whilst giving poorer forward conduction.