DEUTERIUM ATOM INTERACTION WITH DIAMOND (100) STUDIED BY X-RAY PHOTOELECTRON-SPECTROSCOPY

The interaction of atomic deuterium with diamond (100) has been studied by X-ray photoelectron spectroscopy (XPS). Reproducible cleaning and conditioning procedures have been developed using atomic hydrogen exposure and heating to 1450 K in ultrahigh vacuum. As the clean diamond surface is exposed to atomic deuterium, the FWHM of the C 1s transition initially broadens for low atomic deuterium exposures. Increasing the atomic deuterium exposure results in a sharpening of the C 1s transition. This is essentially reversible by stepwise heating to desorb the deuterium. The C 1s broadening/sharpening phenomenon may be due to the electronic inhomogeneity caused by partial deuteration of the surface region sampled by XPS. Complete deuteration leads to a more homogeneous chemical environment and thus the C 1s line sharpens. These results suggest that deep deuteration of diamond (100) may take place upon exposure to atomic deuterium. The inhomogeneity of the surface region caused by Ar+ ion bombardment has a similar broadening effect on the C 1s line. Charging effects were found to be insignificant. Deuteration of the diamond (100) surface by atomic deuterium results in apparent shifts of the C 1s binding energy, dependent (in sign) upon n-type or p-type doping in the diamond. This is consistent with band bending effects in the surface region caused by the removal of the surface state by deuterium adsorption. It is demonstrated that graphite overlayers on diamond cannot be removed with atomic D or molecular oxygen at high temperatures.