Oscillatory Nonmetal-Metal Transitions of Ultrathin Sb Overlayers on a GaAs(110) Substrate

Based on first-principles calculations, an Sb film on GaAs(110) is found to be nonmetallic at 1 and 3 monolayer (ML) coverages, and metallic at 2, 4, and higher ML coverages. These unusual oscillatory nonmetal-metal transitions are explained in terms of a generalized Wilson rule, constrained by the relative magnitudes of the separation and width of the subbands derived from the quantum-well states. The present study also establishes the existence of magic stability of the film at the odd numbers of monolayers, and strong interlayer spacing oscillations.