Metal–Organic Chemical Vapor Deposition of 2D Semiconducting Bi ₂ O ₂ S for High‐Performance Field‐Effect Transistor

Bi 2 O 2 S has emerged as a promising 2D semiconductor for high‐performance field‐effect transistor (FET) applications, effectively addressing limitations observed in conventional 2D materials, including environmental instability, challenges with achieving optimal bandgaps, and insufficient static power efficiency. However, practical application of Bi 2 O 2 S has been hindered by synthesis challenges; previous methods often relied on high‐temperature processes (>700 °C) for precursor sublimation resulting in the formation of undesired phases or solution‐based approaches that compromise material quality. In this work, the growth of single‐crystalline Bi 2 O 2 S nanoplates at a low temperature of ≈400 °C is demonstrated using metal–organic chemical vapor deposition (MOCVD), achieving a bandgap of 1.2 eV compatible with Si‐based devices. Fabricated Bi 2 O 2 S‐based FETs through this process exhibit excellent electrical performance, with a maximum on/off ratio of 3.6 × 10⁹ and a field‐effect mobility of 227 cm 2 V −1 s −1 , benefiting from the low effective mass (0.15 m 0 ) inherent to Bi 2 O 2 S. Furthermore, Bi 2 O 2 S photodetectors display remarkable optoelectronic characteristics, including a high responsivity of 11,577 A W −1 , rapid response time in the millisecond range, and a specific detectivity of 10 14 Jones. These results confirm Bi 2 O 2 S's potential as a versatile semiconductor for next‐generation electronics, offering both BEOL‐compatible low‐temperature synthesis and high‐speed, low‐power device capabilities.