Ferroelectric Photodetector with High Current on-off Ratio (∼1 x 104%) in Self-Assembled Topological Nanoislands

Ferroelectric photodetectors have attracted intensive interest because of the polarization-dependent photoresponse and efficient carrier separation and transport. However, the photoresponsivity and photo-to-dark current (on-off) ratio are limited by the large bandgap. Here, an enhanced current on-off ratio (1.15 X 10(4)%) was discovered at cross-shaped charged domain walls topologically confined in self-assembled BiFeO3 nanoisland arrays. Different from the conventional nonconductive ferroelectric domains, the center-type topological quad-domains also exhibit tunable conductance by external external electric field, which stimulates the distinct current on-off ratio of 1.12 x 10(4)% at center-convergent and 1.65 X 10(3)% at center-divergent quaddomains, respectively. Furthermore, the prototype devices based on these ferroelectric nanoislands exhibit a high photoresponsivity (1.8 X 10(3)A/W) and broadband spectrum response (from visible to infrared), demonstrating the outstanding photoelectric performance in the low-dimensional ferroelectric topological textures.