Understanding the Clean Interface between Covalent Si and Ionic Al2O3

TL;DR

This study uses first principles calculations and a novel optimization method to analyze the atomic and electronic structure of the Si/Al2O3 interface, revealing a clean, covalently bonded heterointerface with promising electronic properties.

Contribution

It introduces a modified basin-hopping method for interface structure prediction and demonstrates the formation of a clean, covalently bonded Si/Al2O3 interface with ideal electronic characteristics.

Findings

All interface Si atoms are fourfold coordinated.

The interface exhibits a large LDA band gap.

No gap states are present at the interface.

Abstract

The atomic and electronic structures of the (001)-Si/(001)-gamma-Al2O3 heterointerface are investigated by first principles total energy calculations combined with a newly developed "modified basin-hopping" method. It is found that all interface Si atoms are fourfold coordinated due to the formation of Si-O and unexpected covalent Si-Al bonds in the new abrupt interface model. And the interface has perfect electronic properties in that the unpassivated interface has a large LDA band gap and no gap levels. These results show that it is possible to have clean semiconductor-oxide interfaces.