Abstract

We report optical and electrical measurements contributing for a better characterization of the relevant photoactive center levels in undoped photorefraetive Bi₁₂Ti0₂₀ (BTO) crystals grown in Brazil. A center responsible for photoehromism was identified at about 0,42eV, probably below the conduction band (CB). Two other defect centers were clearly identified at 0.17 eV and at 0.60 eV, Different centers between 1.0 and 0.85, probably above the valence band (VB), were mesured using different techniques which probably correspond to the same electron-acceptor defect responsible for dark p-eonduetivity which was already reported in the literature. Classical photoconductivity experiments indicated electron-donor centers at least at about 2.2 and 2.5 eV, Holographic techniques indicated the presence of at least two photoactive centers closer than 1.6 eV from CB, one of which could be an empty one.

© 2005 Optical Society of America