Near‐infrared self‐powered RuS 2 x Se 2−2 x alloy photodetector via chemical vapor deposition RuSe 2 and post‐sulfurization process

Abstract Ruthenium (Ru)‐based chalcogenide (S, Se) is a promising material in various fields, such as optics, photoelectrodes, and electrocatalysis, owing to its suitable bandgap for generating charge carriers under light illumination ranging from visible to near‐infrared (NIR) and its high absorption coefficient. In this study, we report the synthesis of RuSe 2 thin films by chemical vapor deposition (CVD) with a bandgap matching the NIR region at 0.52 eV. Further, we demonstrated RuS 2 x Se 2−2 x alloy films using the post‐sulfurization process after CVD RuSe 2 with a tunable bandgap from 0.52 to 1.39 eV depending on sulfur composition. Remarkably, RuS 2 x Se 2−2 x alloy film metal–semiconductor–metal (MSM) photodetector sulfurized at 500 °C, with a 0.75 eV bandgap, exhibits enhanced broad absorption across NIR spectral ranges, suppressed dark current and high photoresponsivity in NIR wavelengths range even at zero‐bias. We believe the bandgap‐tunable RuS 2 x Se 2−2 x thin film through an efficient deposition method could be suitable for various optoelectronic applications.