Development of RuS₂ for near-infrared photodetector by atomic layer deposition and post-sulfurization

The chalcogenides of platinum-group metals (PGMs) have been known to be present in minerals and the intermediate products of refining. Over recent years, their applications in various fields, including catalysis, have been explored. Given that certain PGM chalcogenides behave as compound semiconductors, they can be used as materials for photodetectors. In this study, RuS₂, featuring a bandgap suitable for near-infrared photodetectors, was prepared by forming Ru on a SiO₂/Si substrate via the atomic layer deposition method using [Ru(TMM)(CO)₃] as the precursor. Annealing was conducted at 800 °C for 1 h under H₂S flow. High-resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD) analysis clearly confirmed that the as-deposited hexagonal close-packed (hcp) Ru transformed to cubic RuS₂ after post-annealing. The surface morphologies, chemical states, and electrical and optical properties of RuS₂ were investigated. The influence of the metallic Ru surface morphology prior to sulfurization on the reaction between Ru and H₂S was also discussed. To evaluate the potential of using RuS₂ as a photodetector, a photodetector was fabricated by forming electrodes on RuS₂ to measure its photocurrent under near-infrared light. Thus, RuS₂ was proven to exhibit a short response time (59 μs) and generate a photocurrent of 84 nA under near-infrared light at 940 nm.