Surface core level shifts on InP(110): Use of Sb overlayers

The surface core level shift of the P2p from a clean InP(110) surface has been studied by use of the Sb overlayer. It is shown that the nonreactive Sb overlayer removes the surface core level shift and does not introduce any other component. The unique possibility to separately characterize the bulk component allows a precise determination of the surface core level shift. We show that the surface P2p core level is shifted to lower binding energy by −0.29 eV, while an opposite and nearly equal in magnitude +0.30 eV shift is established for the In4d.