Characterization of the Contact Layer Formed by Ar Ion Implantation Into Homoepitaxial Diamond Film

In this study, we characterized the contact layer formed by Ar ion implantation into homoepitaxial diamond films by applying X-ray photoelectron spectroscopy (XPS), and determined specific contact resistances between the layers and pad metal by the transmission line model (TLM) techniques for the first time. The resulting specific contact resistance value of 10-4ohm cm2 indicates capability of the layer as a practical device contact. The diamond thin film was grown homoepitaxially on high-pressure and high-temperature (HPHT) synthetic Ib diamond (100) substrate by microwave-plasma CVD method. 40keV Ar ions were irradiated at doses of 1x1014, 1x1015 and 1x1016 ions/cm2 under room-temperature. Then, Au/Pt/Ti were evaporated and patterned to make the TLM metal pads. The resulting contact resistances showed a strong dependence on the amount of Ar dose even at the higher dose region. The lowest contact resistance value of 10-4 ohm cm2 was obtained in the case of 1x1016 ions/cm2 doses after 400 annealing in nitrogen atmosphere. Farther, applying this metal / ion implanted layer structure as an ohmic contact, planer type Schottky barrier diodes were fabricated on high homo-epitaxial diamond films. Their current - voltage characteristics especially at a high temperature are also introduced and discussed.