Spin-casted (Gd–Zn) co-doped BiFeO3 thin films for sustainable oxide-electronics

Abstract

The emerging paradigm of oxide-based devices are reshaping the frontiers of sustainable electronics and enabling new functionalities like ferroelectric-photovoltaics, photo-catalytic activity, ferroelectric logics, and terahertz-scale actuation. The intriguing advantages of BiFeO3 (BFO) based oxide electronics offers the possibility of combining electric and magnetic degrees of freedom and is of interest in applications ranging from non-volatile random-access memories, multiple state storage media, tunnelling barriers, actuation, and sensors. Here, we investigate structural evolution and device performance of a cost-effective and unexplored BFO doped derivative i.e. (Gd, Zn) co-doped BFO thin films synthesized using commercially viable spin-casting technique. Owing to the competing change in dopant cation sizes w.r.t. Host lattice, ABO3 rhombohedral perovskite structure of the BFO did not transform while the optical band gap sequentially reduced from 2.65 to 2.53 eV with increasing Gd–Zn co-dopant concentration. Further, the effects of co-doping and asymmetric electrodes on the IV-characteristics of capacitors and the underlying conduction mechanism of these devices are investigated. Photoconductivity studies show three orders larger photocurrent arising from grain-boundary contributions in 2% (Gd, Zn) – BFO film exhibiting rapid, stable and repeatable photo-response which makes them useful for photosensitive capacitor applications.