Surface conductive layers on (111) diamonds after oxygen treatments

Surface conductive layers (SCL) on oxidized (111) diamonds with smooth surfaces after exposure to air were detected and characterized by Hall effect measurements and Schottky junction characterizations. The reproducibility of the SCL is confirmed by a sequence of wet chemical oxidation treatments. The SCL vanishes by thermal annealing at temperature higher than 460 K in He atmosphere, and recovers in air. Hall effect measurements and Schottky junction properties show that the conductivity is p-type with a sheet hole concentrations around of 1012 cm− 2 and Hall mobilities between 5 and 130 cm2/V s. Furthermore, Schottky junction characteristics indicate that the Fermi level is unpinned at the (111) surface. These characteristics are similar to those generated by hydrogen termination, and are discussed in the frame hood of surface carbon dangling bond passivation most likely by OH molecules.