Effect of surface modification on the radiation stability of diamond ohmic contacts

The ohmic contact interface between diamond and metal is essential for the application of diamond detectors. Surface modification can significantly affect the contact performance and eliminate the interface polarization effect. However, the radiation stability of a diamond detector is also sensitive to surface modification. In this work, the influence of surface modification technology on a diamond ohmic contact under high-energy radiation was investigated. Before radiation, the specific contact resistivities (rho c) between Ti/Pt/Au-hydrogen-terminated diamond (H-diamond) and Ti/Pt/Au-oxygen-terminated diamond (O-diamond) were 2.0 x 10-4 omega & sdot;cm2 and 4.3 x 10-3 omega & sdot;cm2, respectively. After 10 MeV electron radiation, the rho c of Ti/Pt/Au H-diamond and Ti/Pt/Au O-diamond were 5.3 x 10-3 omega & sdot;cm2 and 9.1 x 10-3 omega & sdot;cm2, respectively. The rates of change of rho c of H-diamond and O-diamond after radiation were 2550% and 112%, respectively. The electron radiation promotes bond reconstruction of the diamond surface, resulting in an increase in rho c.