Optical control of polarization in ferroelectric heterostructures

In the ferroelectric devices, polarization control is usually accomplished by application of an electric field. In this paper, we demonstrate optically induced polarization switching in BaTiO 3 -based ferroelectric heterostructures utilizing a two-dimensional narrow-gap semiconductor MoS 2 as a top electrode. This effect is attributed to the redistribution of the photo-generated carriers and screening charges at the MoS 2 /BaTiO 3 interface. Specifically, a two-step process, which involves formation of intra-layer excitons during light absorption followed by their decay into inter-layer excitons, results in the positive charge accumulation at the interface forcing the polarization reversal from the upward to the downward direction. Theoretical modeling of the MoS 2 optical absorption spectra with and without the applied electric field provides quantitative support for the proposed mechanism. It is suggested that the discovered effect is of general nature and should be observable in any heterostructure comprising a ferroelectric and a narrow gap semiconductor. Controlling the polarization state in ferroeletric materials is a prerequisite for their application. Here an approach is presented to optically manipulate the polarization of ferroelectric BaTiO 3 by exploiting photogenerated carriers at the interface with a two-dimensional semiconducting MoS 2 film.