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

Ren, Xuanyu; An, Xuyang; He, Xinxin; Feng, Wei; Wang, Boqiang; Chen, Wenshuai; Gao, Feng; Zhang, Jia et al. · Nano Lett · 2026

basic_science · Level V

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Abstract

Bi<sub>2</sub>O<sub>2</sub>Se 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 Bi<sub>2</sub>O<sub>2</sub>Se nanosheets at a lower temperature of 500 °C. The self-powered photoelectric detector with an asymmetric structure was fabricated using a Bi<sub>2</sub>O<sub>2</sub>Se nanosheet as channel material, exhibiting an ultralow dark current of ∼10 fA, weak-light detection capability (50 nW/cm<sup>2</sup>), and detectivity up to 1.06 × 10<sup>13</sup> Jones. The devices also show fast response time and excellent long-term stability with <10% degradation after 12 months in the atmospheric environment. Furthermore, single-pixel imaging demonstrates high contrast and fidelity. This work establishes a practical route for low-temperature growth of high-quality Bi<sub>2</sub>O<sub>2</sub>Se nanosheets and highlights its strong potential for weak-light detection, broadband sensing, and chip-scale photonic systems.