First-principles investigation of the electron work function for the (001) surface of indium oxide In2O3 and indium tin oxide (ITO) as a function of the surface oxidation level

The structure and properties of the (001) surface of indium oxide (In 2 O 3 ) and indium tin oxide (ITO) are investigated theoretically. Ultrasoft pseudopotentials and the PBE exchange-correlation functional are used in our calculations. The calculated band structure of bulk In 2 O 3 , ITO, and their slabs with various surface oxidation levels are compared. Band structure features associated with surface states are detected. The dependence of the calculated electron work function for the In 2 O 3 (001) and ITO (001) surfaces on the surface oxidation level is analyzed. It is found that the work function increases with the oxidation level of the surfaces.