PHOTOEMISSION-STUDY ON NONEQUILIBRIUM EFFECTS IN METALS ON GAAS(110)

We have carried out photoemission studies of the band bending at interfaces between In and low and highly doped GaAs(110) surfaces. Here we show that non-equilibrium phenomena are present at these interfaces. Surface photovoltage dominates at low substrate temperatures and low doping levels. To correctly take into account the experimental results obtained on junctions formed between In and highly p-doped semiconductor surfaces we consider the possibility that the photoemission process itself can induce non-equilibrium process, driving the metal/p-semiconductor diode into reverse bias. We have also investigated the temperature dependence of such phenomena. An analysis of the relative intensities and energies of the Ga 3d and In 4d core levels enables us to separate shifts induced in the surface Fermi level by the change in overlayer morphology from those shifts brought about by a variation in magnitude of non-equilibrium effects. This analysis confirms that, together with surface photovoltage, a different non-equilibrium process has to be considered.