Switchable Optically Active Schottky Barrier in La<sub>0.7</sub>Sr<sub>0.3</sub>MnO<sub>3</sub>/BaTiO<sub>3</sub>/ITO Ferroelectric Tunnel Junction
Alberto Rivera‐Calzada, Fernando Gallego, Yoav Kalcheim, Pavel Salev, Javier del Valle, Isabel Tenreiro, C. León, J. Santamarı́a, Iván K. Schuller
Abstract
Abstract One of the most desirable attributes of non‐volatile memories and memristors is a fast and non‐destructive read out of their resistive state. Prototypical ferroelectric (FE) memories use the bulk photovoltaic response associated to the polarization of FE films to address this requirement by optically sensing binary memory cells. A more advanced type of non‐volatile memories is FE tunnel junctions (FTJs). They feature resistive state ratios R High / R Low up to 10 6 , with a continuum of resistive states accessible, making them promising candidates for neuromorphic computing applications. A novel approach is presented to achieve the optical sensing of the resistive state in a La 0.7 Sr 0.3 MnO 3 /BaTiO 3 /ITO FTJ, by using the Schottky barrier forming in the La 0.7 Sr 0.3 MnO 3 /BaTiO 3 interface to dramatically enhance the optical response of the 5 nm BaTiO 3 (BTO) barrier. Illumination with UV light exceeding the BTO bandgap through the top transparent ITO electrode generates a photovoltaic response in the R High state, with an open circuit voltage V oc of 400 mV at 20 K, enabling the optical sensing of the resistive state. In the R Low state, the Schottky barrier is removed and the photoresponse disappears.