Nonvolatile Negative Optoelectronic Memory Based on Ferroelectric Thin Films

Optically triggered nonvolatile memory is demonstrated in an indium tin oxide (ITO)/BiFeO3 (BFO)/SrRuO3 (SRO) heterostructure. In contrast to conventional devices where optical excitations typically enhance conduction, the prepared device exhibits a pronounced decrease in conductivity (1 x 10(-4)) after laser illumination at wavelengths of 405, 532, and 1064 nm. Also, the negative optoelectronic memory could be reset using optical stimuli and set using an electrical pulse. This characteristic was suppressed through annealing in an oxygen-rich atmosphere, and then reappeared after annealing in an oxygen-poor atmosphere. Systematic investigations on the transport and dielectric properties show that the observed controllable optical/electrical resistance switching behavior is attributed to a modulation of the potential profile at the ITO/BFO interface due to optical and electrical excitations. These observations indicate a feasible avenue for future generations of nonvolatile optoelectronic memory devices.