Record Low Contact Resistivity of 10-8 Ω cm² Ohmic Contacts on Oxygen-Terminated Intrinsic Diamond by Transition Metals Metallization

For the first time, robust ohmic contacts were successfully prepared on oxygen-terminated intrinsic diamond with insulating surface and rare carrier concentration by transition metals (TMs, including Pt, Ru, W, Cr, Zr and V) metallization. The record low specific contact resistance of ${2}.{5}\times {10} ^{-{8}}~\Omega $ cm2 was obtained for Pt contacts, which diffused into diamond in a metallic state and did not generate carbide but sp2 carbon and vacancy defects. We found that the shallow damage layer full of conductive defects like TMs, TM carbides, sp2 carbon and nitrogen-vacancy color centers induced by metallization within diamond is the critical reason for the formation of ohmic contacts, which acts as conductive shunts to connect the electrode contact and bulk diamond. Our findings extended the methodology and theory for the formation of reliable and efficient ohmic contacts on diamond.