Ferroelectric enhanced Ga₂O₃/BFMO-based deep ultraviolet photovoltaic detectors with dual electric fields for photogenerated carrier separation

Ga2O3-based photovoltaic-type (i.e., self-driven) deep ultraviolet (DUV) photodetectors have attracted extensive attention due to their broad application prospects in civilian and military fields. However, their common drawback of poor light sensitivity (i.e., responsivity and detectivity) has greatly hindered their practical applications. In this work, we propose a strategy for constructing a Ga2O3/BiFe0.95Mn0.05O3 (BFMO) ferroelectric/semiconductor heterojunction-based photodetector with higher responsivity and detectivity than single BFMO and single Ga2O3 devices by exploiting the built-in electric field at the Ga2O3/BFMO heterojunction interface (EGa2O3/BFMO) and the ferroelectric depolarization electric field across the BFMO (Edp) to promote the separation of photogenerated carriers. The fabricated Ga2O3/BFMO heterojunction photodetector exhibits tunable performance under zero bias. Higher responsivity (19.01 mA W^-1 @ 260 nm) and detectivity (4.52 x 10¹¹ Jones @ 260 nm) are observed for the photodetector in the upward poling state than that in the unpoled state, which can be attributed to the coupling effect of Edp and EGa2O3/BFMO. Moreover, the photodetector shows even higher responsivity (23.54 mA W^-1) and detectivity (5.58 x 10¹¹ Jones) under weak light illumination (P260nm = 0.002 mW cm^-2), with values much higher than those reported for Ga2O3-based heterojunction photodetectors. This work offers an effective approach for boosting the performance of self-driven UV photodetectors.