Ohmic contact for p-type diamond without postannealing

A new formation method of Ohmic contacts without postannealing was proposed for p-type boron-doped diamond. The diamond surface was partially covered with Au electrodes and then illuminated with vacuum ultraviolet light in an oxygen atmosphere. Through these processes, the hydrogen-terminated diamond surface was oxidized selectively, except for the areas beneath the Au electrodes. Consequently, the surface conductivity became negligibly small on the bare surface between the two electrodes, whereas as-deposited Au electrodes showed Ohmic properties for the lightly doped diamond with boron concentration of ∼1015 cm−3. The Ohmic properties were stable at temperatures up to 700 K.