Band bending of cleaved GaAs(110) surface

After cleaved in UHV, the dynamic band bending of GaAs(110) surface was investigated using in situ XPS measurement. It was found that the Fermi level of heavy doped n-GaAs and p-GaAs shifted to the midgap 0. 4 eV and 0. 3 eV, respectively, Fermi level difference of 1. 3 eV between heavy doped n-GaAs and p-GaAs was revealed. In fact, the theoretical band gap of GaAs is 1. 42 eV, which suggests that our experimental results should be believable. Based on the experimental results, it was concluded that the surface band bending was caused neither by intrinsic surface states in GaAs, the residual gas in UHV, nor the X-ray radiation, The band bending should be caused mainly by the surface defects induced during the cleavage and more probably during lattice relaxation.