Surface transfer doping of oxidised silicon-terminated (111) diamond using MoO3

High-resolution core-level photoemission and Kelvin probe was used to examine surface transfer doping of oxidised silicon-terminated (111) diamond with the molecular acceptor MoO3. A downward shift in the Fermi level position, relative to the diamond valence band maximum, commensurate with p-type surface doping was observed only for MoO3 coverages in the range 0.2–0.6 ML and above. For lower MoO3 coverages the appearance of distinct charge states of MoO3 is ascribed to electron transfer from surface charge traps with an estimated density in the range 1–3 × 1013 cm−2. Atomic force microscopy imaging suggests significant disorder of the surface compared to similarly prepared (100) diamond surfaces.