Doubling data density
An electronic device that could lead to smaller, low-power memory chips can now be controlled and probed by light, as revealed by research from KAUST. The device is a ferroelectric tunnel junction ( #FTJ ) that contains a thin layer of a ferroelectric material sandwiched between two electrodes. #Ferroelectric materials are intrinsically polarized so that negative electrical charge concentrates on one side of the layer and positive charge clusters on the opposite side. Applying an electric field flips this polarization, and the two states can represent the “1”s and “0”s of binary data. The device crucially does not need power to retain this data. Tom Wu of from the KAUST Material Science and Engineering program and colleagues created an FTJ containing a film of ferroelectric samarium-doped bismuth iron oxide ( #SBFO ) that was just three to nine nanometers thick (Nature Communications, “Optically controlled electroresistance and electrically controlled photovoltage in ferroelectric tunnel junctions”). One electrode was made of platinum and the other was niobium-doped strontium titanate ( #NSTO ), a light-sensitive semiconductor.