The investigation of the photorefractive properties in various sillenite crystals (Bil2Si020 - Bil2Ge020) is presented. While in some crystals we find a photorefractive effect governed by electron migration as commonly admitted, we, for the first time, demonstrate that holes play the most important role in the grating recording process in some EGO samples. Thus controlling the charge carrier responsible for the photorefractive effect might lead to an optimisation of the material properties for device design.
J C Launay,
"Photorefractive Effect Due To Holes In Undoped BGO Crystals", Proc. SPIE 0812, Progress in Holography, (6 October 1987); doi: 10.1117/12.941601; https://doi.org/10.1117/12.941601