Figure 1: Properties of as-grown BiFeO 3 thin films.
From: Non-volatile memory based on the ferroelectric photovoltaic effect
(a) Schematic drawing of BiFeO3 unit cell on SrTiO3 substrate with 4° miscut towards (110) direction. The interface between the bottom electrode and BiFeO3 at the step edge favors one of the eight degenerate polarization directions. (b) Topography of the BiFeO3 film with steps that are clearly visible and obtained by atomic force microscopy (AFM). (c) Out-of-plane (OOP) and (d) in-plane (IP) domain images of the BiFeO3 film. A 2-μm × 2-μm square region with opposite polarization direction was created by scanning the area with a DC bias applied to the AFM tip. (e) Typical P–V hysteresis loop (black) obtained at room temperature using 1 kHz triangle wave. The I–V curve (red) is also shown. (f) Current–voltage curves of the as-grown film obtained with and without illumination (grey line: in dark; red line: under light with polarization down; blue line: under light with polarization up. Light source: halogen lamp; energy density: 20 mW cm−2). Scale bars, 1 μm.
