The atomic and electronic structures of the $(001)\mathrm{\text{−}}\mathrm{Si}/(001)\mathrm{\text{−}}\gamma \mathrm{\text{−}}{\mathrm{Al}}_2{\mathrm{O}}_3$ 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.

• Received 3 March 2009

DOI:https://doi.org/10.1103/PhysRevLett.103.116101