Submonolayer barium passivation study for germanium(100)/molecular beam epitaxial Al2O3

Abstract

The passivation effect of a Ba submonolayer with (2×1) and (4×1) surface reconstructions are investigated for Ge(001)/Al2O3 interfaces. The interface characteristics are evaluated by capacitance-voltage and ac conductance techniques at various temperatures. It is found that the Ba passivating effect on Ge is dose dependent below one monolayer. At the same time, Ge oxides are suppressed by the presence of a Ba submonolayer. The interface is thermally stable, even at a temperature higher than the desorption temperature of Ge oxides. Forming gas annealing at this temperature yields a relatively symmetric distribution of interface traps in the Ge band gap.