Low-Temperature Growth of High-Quality Bi 2 O 2 Se Nanosheets Enabling Weak-Light Detection with Ultralow Dark Current

Bi2O2Se is an emerging n-type semiconductor, but conventional growth methods often rely on high temperatures or complex multisource systems that introduce defects and limit device integration. Herein, we report a simplified and modified physical vapor deposition (PVD) strategy enabling the growth of single-crystal Bi2O2Se nanosheets at a lower temperature of 500 °C. The self-powered photoelectric detector with an asymmetric structure was fabricated using a Bi2O2Se nanosheet as channel material, exhibiting an ultralow dark current of ∼10 fA, weak-light detection capability (50 nW/cm2), and detectivity up to 1.06 × 1013 Jones. The devices also show fast response time and excellent long-term stability with 2O2Se nanosheets and highlights its strong potential for weak-light detection, broadband sensing, and chip-scale photonic systems.