Role of surface oxygen vacancies in photoluminescence of tin dioxide nanobelts

The role of surface oxygen vacancies in the optical properties of tin dioxide nanobelts is investigated in this paper. Using a first-principles approach, based on the density functional theory combined to a very accurate exchange correlation functional, we characterize SnO(2) (101), that is the nanobelt largest surface. We show that the presence of surface oxygen vacancies leads to the appearance of (i) occupied states located at about 1 eV above the valence band and (ii) unoccupied states lying in resonance with the conduction band. Photoluminescence characterization performed on samples of SnO(2) nanobelts at low temperature shows that the basic spectral features of luminescence are in excellent agreement with theoretical predictions.