Salt-Templated Epitaxy and Transfer of Single-Crystal 2D Bi2O2Se Nanosheets for High-Performance Broadband Photodetectors

The integration of high-mobility and band gap-tunable two-dimensional (2D) materials with silicon technology is widely considered a pressing challenge for next-generation high-density electronics. However, 2D materials can be grown on only limited archetypal substrates by chemical vapor deposition, which usually produces cracks, contamination, and wrinkles during the transfer process, leading to electronic performance attenuation. The advance of a damage-free transfer approach to seamlessly combine 2D atomic layers with arbitrary substrates is essential for making full use of their intrinsic merits and critical for lab-to-fab transition. Here, self-sacrifice and water-soluble substrates are present for the epitaxy growth and low-damage transfer of 2D bismuth oxyselenide (Bi 2 O 2 Se) nanosheets. The as-synthesized Bi 2 O 2 Se nanosheets can be transferred to other substrates without introducing extra etching damage. Consequently, the Bi 2 O 2 Se nanosheets exhibit a high intrinsic electrical mobility of 501.5 cm 2 ·V –1 ·S –1, a wide-range (405–1550 nm) photoelectrical response with a responsivity of 9.2 × 10 6 A/W, and a detectivity of 2.9 × 10 15 Jones under 808 nm irradiation. This study paves the way for the low-defect transfer of large-area epitaxial 2D materials, addressing the integration problems between high-quality 2D materials and silicon technology.