Stability and band offsets between Si and LaAlO3

Abstract

The replacement of traditional SiO2 with high-k oxides allows the physical thickness of the gate dielectric to be thinner without the tunneling problem in Si-based metal-oxide-semiconductor field-effect transistors. LaAlO3 appears to be a promising high-k material for use in future ultra large scale integrated devices. In the present paper, the electronic properties of Si/LaAlO3 (001) heterojunctions are investigated by first-principles calculations. We studied the initial adsorption of Si atoms on the LaAlO3 (001) surface, and found that Si atoms preferentially adsorb on top of oxygen atoms at higher coverage. The surface phase diagrams indicate that Si atoms may substitute oxygen atoms at the LaO-terminated surface. The band offsets, electronic density of states, and atomic charges are analyzed for the various Si/LaAlO3 heterojunctions. Our results suggest that the Si/AlO2 interface is suitable for the design of metal oxide semiconductor devices because the valence and conduction band offsets are both larger than 1 eV.