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

Bi₂O₂S 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 Bi₂O₂S 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 Bi₂O₂S 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 Bi₂O₂S-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 cm² V^-1 s^-1, benefiting from the low effective mass (0.15 m₀) inherent to Bi₂O₂S. Furthermore, Bi₂O₂S 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 10¹⁴ Jones. These results confirm Bi₂O₂S's potential as a versatile semiconductor for next-generation electronics, offering both BEOL-compatible low-temperature synthesis and high-speed, low-power device capabilities.