Optically-induced non-linear optical effects in indium-tin oxide crystalline films

摘要

We have studied thin nanolayers (with thicknesses of about 1-2 nm) between In_2O_3:Sn (indium-tin oxide (ITO)) crystalline films and glass substrates using the photo-induced optical second harmonic generation (PISHG) method. The maximal PISHG response observed for the pump-probe delay times was about 26 ps. The performed experimental measurements and quantum chemical theoretical simulations show that the observed effects are caused by two factors. The first is caused by the film-glass interface potential gradient and the second is a consequence of additional trapping levels appearing in the energy gap, particularly due to Sn doping. PISHG may be considered as a sensitive tool for such kinds of semiconductors.