Formation energy, lattice relaxation, and electronic structure of Al/Si/GaAs(100) junctions

We investigated the energetics as well as the structural and electronic properties of chemically abrupt Al/GaAs(100) and engineered Al/Si/GaAs(100) Schottky diodes with 2 monolayers of Si using the ab initio pseudopotential approach. Results for the atomic relaxation at the interface, its influence on the Schottky barrier, and the dependence of the formation energy on the As and Ga chemical potentials are presented. We show that a reversal in the relative stability of the As- and Ga-terminated junctions occurs within the experimentally accessible range of the As and Ga chemical potentials, for both Al/GaAs and Al/Si/GaAs interfaces. This reversal could explain the role played by the excess cation and anion flux in the fabrication of tunable Al/Si/GaAs(100) Schottky diodes.