Unraveling the Nanosecond Photoresponse of Layered HgPSe.

Chalcogen phosphates of transition metals make up a well-known group of antiferromagnetic semiconductors with the general formula MPX, where M represents a transition metal and X is a chalcogen, either sulfur or selenium. Most of these compounds adopt a similar structure; however, mercury phosphochalcogenides present an exception with their unique van der Waals layered structure. Transition metal chalcogenides are highly appealing materials for photodetectors due to their exceptional optoelectronic properties. Among them, HgPSe, a layered van der Waals phosphoselenide, shows promise for photodetection over a broad spectral range, from visible light to X-rays. Despite this, the electronic processes governing its photoresponse remain unclear. In this study, we demonstrate a nanosecond response time of a HgPSe-based photodetector to visible light and gain deeper insights into the underlying charge carrier dynamics through a comprehensive investigation using complementary time-resolved experimental techniques. Our findings on the role of carrier traps provide a potential pathway for optimizing optoelectronic device performance.