ELECTRONIC SURFACE-PROPERTIES OF CLEAVED GAP(110)

Electronic surface properties of UHV cleaved GaP (110) are investigated by contact potential difference measurements and photoemission yield spectroscopy. The p-type samples show practically no band bending; n-type GaP exhibits surface Fermi level stabilization about 1.65 eV above the valence band maximum. Two surface state bands are found in the gap. The importance of the first one, located near the valence band edge, depends on the cleavage. The other one is found in the upper part of the gap. An evaluation of the corresponding density of states shows it may correspond to the tail of an intrinsic surface band, mostly empty, the maximum of which would be closer to the conduction band. By comparing with results on other III-V compounds, it is suggested that a surface relaxation smaller for GaP than for GaAs may explain their different electronic properties. © 1979.