Ultrahigh responsivity of non-van der Waals Bi₂O₂Se photodetector

Bismuth oxyselenide has recently gained tremendous attention as a promising 2D material for next-generation electronic and optoelectronic devices due to its ultrahigh mobility, moderate bandgap, exceptional environmental stability, and presence of high-dielectric constant native oxide. In this study, we have synthesized single-crystalline nanosheets of Bismuth oxyselenide with thicknesses measuring below ten nanometers on Fluorophlogopite mica using an atmospheric pressure chemical vapor deposition system. We transferred as-grown samples to different substrates using a non-corrosive nail polish-assisted dry transfer method. Back-gated Bi₂O₂Se field effect transistors showed decent field effect mobility of 100 cm²V^-1s^-1. The optoelectronic property study revealed an ultrahigh responsivity of 1.16 × 10⁶A W^-1and a specific detectivity of 2.55 × 10¹³Jones. The samples also exhibited broadband photoresponse and gate-tunable photoresponse time. These results suggest that Bi₂O₂Se is an excellent candidate for future high-performance optoelectronic device applications.