Sm, Nd doped BiFeO3 epitaxial film for photodetector with extremely large on-off current ratio.

BiFeO3 is one of the star materials in the field of ferroelectric photovoltaic for its relatively narrow bandgap (2.2-2.7eV) and better visible light absorption. However, a high temperature over 600℃ is indispensable in the usual BiFeO3 growth process, leading to impure phase, interdiffusion of components near the interface, oxygen vacancy and ferrous iron ions, which will result in large leakage current and greatly aggravate the ferroelectricity and photoelectric response. Here we prepared Sm, Nd doped epitaxial BiFeO3 film via a rapid microwave assisted hydrothermal process at low temperature. The doped BiFeO3 film exhibits narrow bandgap (1.35eV) and super small dark current, the on-off current ratio reaches over 105. The decrease in band gap and +2/+3 variable element doping are responsible for the excellent photo response. The excellent photo response performances are much better than any previously reported BiFeO3 films, which has great potential for applications in photodetection, ferroelectric photovoltaic and optoelectronic devices.&#xD.