Comparative study of the electronic structures of the In and Sn/In2O3 (111) interfaces

TL;DR

This study investigates how metallic indium and tin deposition affect the electronic structure of In2O3 (111), revealing formation of a 2D electron gas and differences in band bending caused by the two metals.

Contribution

It provides new insights into the surface electronic states and band structure modifications induced by indium and tin on In2O3 (111) surfaces.

Findings

Formation of a 2D electron gas at In deposition

Indium shifts Fermi level and creates a new interface state

Tin causes larger band bending without forming a surface state

Abstract

The electronic structure of the transparent semiconductor In2O3 has been studied by angle resolved photoemission spectroscopy upon deposition of metallic indium and also tin on the surface of the semiconductor. By deposition of metallic indium on In2O3 (111) single crystals, we detected the formation of a free-electron like band of effective mass (0.38+-0.05) m0. At low coverages, metallic In shifts the Fermi level of In2O3 to higher energies and a new electronic state forms at the metal/semiconductor interface. This state of two-dimensional character (2D-electron gas) is completely responsible for the electrical conduction in In2O3 (111) at the surface region and has a band dispersion, which does not correspond to the previously found surface accumulation layers in this material. Despite the similarity of the electronic properties of In and Sn, a larger downward banding was observed by Sn coverage, which was not accompanied by the appearance of the surface state.