Characteristics of Au/Ti/p-diamond ohmic contacts prepared by r.f. sputtering

Low-resistance ohmic contacts were fabricated on diamond films by boron ion implantation and subsequent Ti/Au bilayer metallization. The I-V measureme nts showed that the as-deposited contacts were ohmic. After annealing at 50 0 degreesC for 10 min in a vacuum of 10(-4) Pa, the I-V characteristics wer e improved significantly. As a result of annealing, the specific contact re sistance (pc) value, measured by the circular transmission line model (CTLM ), decreased from 6.2 x 10(-3) to 1.2 X 10(-6) Omega (.) cm(2). Compared wi th the value calculated by the transmission line model (TLM), the rho (C) v alue was reduced by more than two orders of magnitude for the annealed cont acts. The CTLM should be more accurate in measurement than the TLM. The cha nges of the rho (C) value with the operating temperature indicated that the rho (C) value decreased with increasing operating temperature at low tempe ratures. Tunnelling was suggested to be the dominant transport mechanism at the metal/diamond interface. The band model was quantified. Copyright (C) 2001 John Wiley & Sons, Ltd.