Yb/GaAs (110): The pinning behavior of the rare earth GaAs interface

Abstract

The effect of the room temperature interaction of an increasing coverage of the rare earth metal, Yb, on the Fermi level pinning behavior of n-GaAs (110) has been studied in detail. Soft X-ray photoemission spectroscopy was used to obtain information on the variation of the Fermi level position in the band gap via photoelectron emission from the As 3d and Ga 3d core level states. Both As and Ga interact with the overlayer to such a degree that we have used two independent methodologies to obtain a reliable estimate of the Schottky barrier height. The established limits for the barrier height are 0.61–0.72 eV. The results of this study show that the pinning position of the Fermi level is established well before the interface constituents are fully reacted and is stable for higher overlayer coverages. The Schottky barrier height is consistent with the low electronegativity of the rare earth metals.