Field Emission Spectroscopy Measurements Of Graphene/N-Type Diamond Heterojunction

In this study, a graphene/n-type diamond heterojunction was fabricated by a wet-transfer process on hydrogen-terminated heavily phosphorus-doped diamond. Ultraviolet photoelectron spectroscopy (UPS) and field-emission electron spectroscopy were conducted to study the band structure of the graphene/n-type diamond heterojunction and its field emission mechanism. UPS suggests that an internal barrier is formed in the diamond by upward band bending near the graphene-diamond interface. The work function of graphene is estimated to be 3.72eV. Field emission occurs from the Fermi level of graphene at low voltages, and then electron emission from the valence band of diamond starts at increased voltages. The results indicate that electron emission limited by surface termination changes to graphene-oriented emission following the formation of the heterojunction.