Electron spectroscopy and diffraction study of the origin of CVD diamond surface conductivity

The origin of surface conductivity (SC) of a CVD diamond (001) single-domain 2×1 surface was studied by electron spectroscopy and electron diffraction in UHV. In order to change SC of the diamond in UHV, two annealing stages were used: annealing at 300°C and annealing at 550°C. From the results of LEED and XPS, the existence of SC was suggested for the first stage of annealing and the absence of SC was suggested for the last stage of annealing. Changes in C KVV AES spectra, C KVV AED patterns and C 1s XPS peak positions were noted between the annealing stages at 300 and 550°C. These changes are interpreted in that the state of hydrogen involvement on a subsurface of diamond (001)2×1 changes as SC changes. From C 1s XPS peak shifts, a lower bound for the Fermi level for SC layers from the valence band top is presented to be ∼0.5 eV.