High-Performance Self-Driven Photodetectors Based on Self-Polarized Bi _0.9Eu _0.1FeO ₃/Nb-Doped SrTiO ₃ p-n Heterojunction

Abstract

Ferroelectric (FE) materials, owing to their remarkable photovoltaic effects, are one of the most promising candidates for self-powered photodetectors. Here, with the pronounced rectification ratio of 10³ at electric bias of ±1.0 V and a low dark current of 12 pA, the self-polarized Bi_0.9Eu_0.1FeO₃ (BEFO)/Nb-doped SrTiO₃ (NSTO) p-n heterojunctions are synthesized. The BEFO / NSTO p-n heterojunctions achieve the excellent photovoltaic effect with a short-circuit current as high as 0.23 mA and an open-circuit voltage of 0.41 V under the  illumination of 405 nm with the light intensity of 151.7 mW/cm². More importantly, the built-in potential in the as-prepared BEFO/NSTO heterojunctions offers the self-powered photo-detecting functionality with the light on/off ratio as high as 2.0 × 10⁴, high responsivity (R = 0.64 mA/W) and detectivity (D* = 1.63 × 10¹⁰ Jones), and fast response speed (50/44 ms) without external bias voltage. Furthermore, even higher R (~ 1.97 mA/W) and D* (5.0 × 10¹⁰ Jones) performances in the weak incident power (1.4 mW/cm²) illumination are demonstrated, better than most previously reported FE-based self-powered photodetectors. Moreover, the devices possess good ambient stability and reproducibility. This paper provides a demo for optically driven high-performance electronic devices based on self-polarized ferroelectric materials.

Keywords: self-polarization, p-n heterojunctions, self-driven photodetector, high on/off ratio, and fast response