Electronic surface properties of uhv-cleaved III–V compounds

Combined CPD and photoemission measurements were performed on uhv-cleaved surfaces of the III–V compounds InAs, GaSb, GaAs and GaP with moderate p-type and n-type dopings. Except for n-type GaP these materials show practically no band bending. N-type GaP exhibits surface Fermi level stabilization at 0.55 eV below the conduction band edge. This is ascribed to an intrinsic empty surface state band in the forbidden zone. On the basis of our experiments together with available data from literature we propose an empirical model for the (110) plane of III–V compounds containing In or Ga as metal and Sb, As or P as non-metal atoms from which the lower edge of the empty surface state band can be predicted. The model indicates that for any of these compounds except for GaP no empty surface state band exist in the band gap on the (110) surface.