The electronic structure and associated properties of antimony-doped tin (IV) oxide have been studied using both the self-consistent-field scattered-wave molecular-orbital cluster approach and the augment- ed-spherical-wave supercell band-structure approach. The calculated molecular-orbital energy eigenvalues and wave functions have been used to interpret several interesting optoelectronic properties of this defect semiconductor. The nature and origin of the energy gap from optical-absorption studies and the valence-band structure from ultraviolet photoelectron spectroscopy (UPS) have been satisfactorily explained using the band structure of pure and antimony-doped tin oxide. It is observed that the antimony ion leads to an impurity band in the band gap and increases the forbidden gap of the host material. This partially filled free-electron-like band is the origin of the UPS peak near the band edge whose intensity grows with the dopant concentration.

• Received 1 February 1995

DOI:https://doi.org/10.1103/PhysRevB.51.13972