UV-light-induced change in ferroelectric polarization mediated by the metal/ferroelectric Schottky interface. a) Schematic band alignment at the Schottky interface between a metal and an n-type semiconductor with conduction band edge (EC), valence band edge (EV), vacuum energy level (E0), Fermi energy (EF), metal work function (Φf), Schottky barrier (ΦB), bandgap energy (Eg), electron affinity (χ), and built-in voltage (Vbi). Introducing ferroelectric bound charge results in an increased built-in voltage (Vbi, up) for an upward-oriented polarization (b) and a decreased built-in voltage (Vbi, down) for a downward-oriented polarization. Upon above-bandgap UV illumination, charge carrier separation in the Schottky junction will improve the charge screening for an upward-oriented polarization (b), but impair the screening for a downward-oriented polarization (c).
