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 measurements showed that the as‐deposited contacts were ohmic. After annealing at 500 °C for 10 min in a vacuum of 10 −4 Pa, the I–V characteristics were improved significantly. As a result of annealing, the specific contact resistance (ρ C ) value, measured by the circular transmission line model (CTLM), decreased from 6.2 × 10 −3 to 1.2 × 10 −6 Ω·cm 2 . Compared with the value calculated by the transmission line model (TLM), the ρ C value was reduced by more than two orders of magnitude for the annealed contacts. The CTLM should be more accurate in measurement than the TLM. The changes of the ρ C value with the operating temperature indicated that the ρ C value decreased with increasing operating temperature at low temperatures. Tunnelling was suggested to be the dominant transport mechanism at the metal/diamond interface. The band model was quantified. Copyright © 2001 John Wiley & Sons, Ltd.