Ohmic contacts to boron-doped diamond

Two types of contacts, namely Au and Au/Ta, were fabricated on B-doped diamond films by rf sputtering deposition. I-V measurements show that our An and Au/Ta contacts have exhibited good ohmic characteristics in their as-deposited states. Upon annealing, their ohmic behaviors were improved to different extent. Compared with Au contact, Au/Ta contact has lower specific contact resistance value and better adhesion. X-ray photoelectron spectroscopy (XPS) analyses indicate that there is an obvious interdiffusion between Au and diamond film in An contact. The interdiffusion was enhanced by annealing. This interdiffusion layer may be the reason why Au contacts are ohmic in the as-deposited and annealed states. As for Au/Ta contacts, XPS analyses show the formation of TaC at the interface between Ta and diamond film in the as-deposited state, there is an increase of TaC in the annealed contact. The presence of TaC promotes our Au/Ta contacts to have better ohmic characteristic. (C) 2003 Published by Elsevier Science B.V.