Abstract
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 BaTiO3-based ferroelectric heterostructures utilizing a two-dimensional narrow-gap semiconductor MoS2 as a top electrode. This effect is attributed to the redistribution of the photo-generated carriers and screening charges at the MoS2/BaTiO3 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 MoS2 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.
Highlights
In the ferroelectric devices, polarization control is usually accomplished by application of an electric field
The most recently reported effects of this nature include ferroelectrically induced resistive switching phenomena and the associated memristive behavior[3], electrical control of antiferromagnetic domains[4], modulation of the electronic transport in 2D semiconductors[5,6,7] and phase transitions at magnetic complex oxide interfaces[8,9], polarization reversal is typically realized via application of an electric field, recently it has been shown that mechanical stress and chemical environment can be used as external stimuli for polarization control[10,11,12]
Taking advantage of the MoS2 photosensitivity, we demonstrate that optical excitation leads to a sizable change in the perpendicular-to-plane electronic transport in the MoS2/BaTiO3/SrRuO3 tunnel junctions—an effect that we term as optical electroresistance effect (OER)
Summary
Polarization control is usually accomplished by application of an electric field. Among the most important properties of ferroelectrics is their strong interaction with light, which gives rise to a variety of the photo-induced phenomena coupled to polarization This includes experimentally observed effects, such as photovoltaic behavior[13] and photostriction[14,15], as well as expected but not demonstrated features, such as optically generated interface metal-insulator transitions[16]. The observed effects may open possibilities for remote control of the electronic properties of ferroelectric-based devices for advanced optoelectronic applications It should be noted, that for any future applications it is important to find out if the speed of optical switching could achieve the same scale as polarization reversal induced by electrical means
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