Low-temperature transport and relaxation of photo-carriers in TiS2

The investigation of non-equilibrium carrier dynamics in two-dimensional semi-metallic materials, particularly at low temperatures, is crucial for elucidating their fundamental properties, including carrier–carrier interactions and electron–phonon scattering mechanisms. In this study, we examine the behavior of 1T-TiS2, utilizing scanning photocurrent microscopy, bias voltage-adjustable photoresponse measurements, and pump-probe techniques to explore the temperature-dependent transport and relaxation of photo-excited charge carriers. We observe a non-monotonic intrinsic photocurrent in the biased device, with a pronounced peak feature occurring at approximately 25 K, which is corroborated by pump-probe measurements that reveal a similar peak in the magnitude and relaxation time of the differential reflectance as a function of the temperature. Our results highlight the unique carrier dynamics in TiS2, offering valuable insights for the design of TiS2-based optoelectronic devices that can operate effectively across a wide temperature range.