Electric-Field-Induced Second-Harmonic Generation Demonstrates Different Interface Properties of Molecular Beam Epitaxy Grown MgO on Si

Abstract

The ability to tune the electrical properties of a metal–oxide–semiconductor structure, especially the chemical nature and the associated electrical properties of the first few layers of the oxide, is of increasing importance in the semiconductor industry. Oxide deposition using molecular beam epitaxy facilitates the control of the interface with the semiconductor at the atomic level. Depending on the characteristics of the first monolayer, the electric-field-induced second-harmonic generation can be shifted, which is correlated to the flat-band voltage shift. Three different oxide–semiconductor interfaces, which originate from different first monolayers, are investigated by electric-field-induced second-harmonic generation and are shown to exhibit different electronic characteristics. Migration of positive oxygen vacancies from the oxide layer toward the Si space-charge region is observed.