Theoretical study of Schottky-barrier formation at epitaxial rare-earth-metal/semiconductor interfaces

We present a detailed computational analysis of the atomic and electronic structure of ErAs/GaAs interfaces in polar and nonpolar crystallographic orientations. ErAs, a rocksalt semimetal, can be grown as a film with high-quality epitaxy on GaAs, a zinc-blende semiconductor. The As sublattice is continuous through the interface, providing a high-quality metal-semiconductor contact. We characterize the electronic structure of this interface using first-principles techniques based on density-functional theory. The Schottky barrier formed at the interface is highly sensitive to the interface orientation and the structural details. We deduce the primary mechanisms for Fermi-level pinning at specific energies within the band gap of the semiconductor.