Temperature-induced metal-insulator transition on a triangular binary system: Sn/Si(111)

Abstract

We report that a metallic Sn/Si(1 1 1 )-root3 x root3-R30degrees surface undergoes a metal-semiconductor transition upon annealing the surface above the transition temperature of 760degreesC. The unique loss peak initially observed weakly from the metallic surfaces in our high-resolution electron-energy-loss spectra shifts gradually towards higher loss energy with increasing temperature. The peak eventually reaches 2.0 eV, revealing a band gap of about 1.2 eV at 810degreesC. We find that a two-dimensional (2D) disordered alloy model, where the semiconducting surface is a 2D mixture of Sn and Si substitutions, is quite consistent with our experimental data.