High-Performance Visible Light Photodetector Based on BiSeI Single Crystal

The continuing demand for new optoelectronic devices drives researchers to seek new materials suitable for photodetector applications. Recently, ternary compound semiconductors have entered researchers' field of vision, among which chalcohalides have attracted special interest because of their rich properties and unique crystal structure consisting of atom chains and inter-chain van der Waals gaps. We have synthesized high-quality BiSeI single crystals with 110-plane orientation and fabricated a photodetector. The optoelectronic measurements show a pronounced photocurrent signal with outstanding technical parameters, namely high responsivity (3.2 A/W), specific detectivity (7 \times 10^10 Jones) and external quantum efficiency (622%) for \lambda = 635 nm, V_\rm ds = 0.1 V and P_\rm opt = 0.23 mW/cm^2. The high performance of BiSeI photodetector and its layer structure make it a promising candidate for low-dimensional optoelectronic applications.