The electronic surface barrier of boron-doped diamond by anodic oxidation

It was shown that a strong anodic oxidation of 100-oriented diamond induces the electronic surface states, which pin the surface Fermi level at about 3.6 eV above the valence-band maximum. The characteristics of the electronic surface barrier were evaluated from the analysis of boron-doped diamond electrodes and correlated with the four-point probe measurements of an oxidized diamond resistor with a boron delta-doped channel. The same evaluation procedure applied to the case of a wet chemical oxidation yielded a surface barrier of 1.9 eV, which is consistent with the data in the literature. The characteristics of the 3.6 eV barrier by the anodic oxidation remained stable after subsequent chemical treatments even at elevated temperatures, and were also not degraded in air for a long time. The x-ray photoemission spectroscopy study showed that the anodic oxidation generates complex oxygen functionalities, like polycarbonate groups, and also C-O-C bridging bond structures with possible contribution of an additional chemisorbed layer. (c) 2008 American Institute of Physics.