Screening Phenomena

Abstract

As indicated in Sect. 7.1, in some investigations (for instance in [6.16]) the photorefractive effect was assumed to be associated with the screening of the internal field in a ferroelectric (the depolarization field) by nonequilibrium carriers. This assumption is based on the fact that, in principle, an internal macroscopic field always exists even in a short-circuited ferroelectric (Sect.4.1). And although the subsequent investigations showed that the photorefractive effect is mainly due to the photovoltaic effect (at least in LiNbO₃:Fe), there are many photoferroelectric phenomena associated with the screening of the internal macroscopic field by nonequilibrium carriers. In [8.1] it was shown that illumination of the ferroelectric SbSI in the intrinsic photosensitivity region in the absence of an external field is accompanied by transitional screening photocurrents and a change in domain structure (the photodomain effect). This group of photoferroelectric phenomena is considered in detail in [1.14]. In this chapter we discuss only some screening phenomena in photoferroelectrics.