Resonant photoemission spectroscopy of Ga 3d two-hole states of GaAs

The Ga 3d two-hole states were observed from GaAs(001)-c(4 x 4), -2 x 4, and (110)-1 x 1 surfaces using resonant photoemission spectroscopy. Multiplet terms (1)G, D-1, and F-3 were clearly distinguished at the photon energy around the 3(p) absorption threshold. The surface components of the two-hole states were observed in the spectra of the (001)-2 x 4 and (110)-1 x 1 surfaces having Ga atoms at the surfaces. The curve-fitting analysis revealed that the intensities of the surface component of the two-hole states were considerably smaller than those of the d(9) states. This is ascribed to the reduced absorption probabilities of the 3p electrons at the surfaces caused by the surface relaxation.