Ultraviolet detection is of great significance due to its wide applications in the missile tracking, flame detecting, pollution monitoring, and so on. The nonlayered semiconductor γ-Bi2 O3 is a promising candidate toward high-performance UV detection due to the wide bandgap, excellent light sensitivity, environmental stability, nontoxic and elemental abundance properties. However, controllable preparation of ultrathin 2D γ-Bi2 O3 flakes remains a challenge, owing to its nonlayered structure, metastable nature, and other competing phases. Moreover, the UV photodetectors based on 2D γ-Bi2 O3 flake have not been implemented yet. Here, ultrathin (down to 4.8 nm) 2D γ-Bi2 O3 flakes with high crystal quality are obtained via a van der Waals epitaxy method. The as-synthesized single-crystalline γ-Bi2 O3 flakes show a body-centered cubic structure and grown along (111) lattice plane as revealed by experimental observations. More importantly, photodetectors based on the as-synthesized 2D γ-Bi2 O3 flakes exhibit promising UV detection ability, including a responsivity of 64.5 A W-1 , a detectivity of 1.3 × 1013 Jones, and an ultrafast response speed (τrise ≈ 290 µs and τdecay ≈ 870 µs) at 365 nm, suggesting its great potential for various optoelectronic applications.
Keywords: 2D γ-Bi 2O 3; ultraviolet detection; van der Waals epitaxy.
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