Ultrafast probing of indium doping on SnTe topological insulator

In this article, we report the optical probing of SnTe (275 nm and 33 nm) and Indium-doped SnTe films (50 nm) which are deposited using thermal evaporation. XRD (X-ray diffraction) and Raman spectroscopy are used to characterize the films. Additionally, the optical characteristics of the material are examined using reflectance and PL (photoluminescence) spectroscopy. Simultaneously, the dynamics of charge carriers are studied using TRUS (Transient reflectance ultrafast spectroscopy). The TRUS probes the thin films in the visible to near-infrared range (400–1600 nm) with a probe latency of a few femtoseconds to 6 ns. The study demonstrates the presence of a resonant state in SnTe, which becomes more prominent and metastable with indium doping. Optical probing of SnTe (275 nm and 33 nm) and indium doped SnTe films (50 nm) which are deposited using thermal evaporation.The films are characterized through XRD (X-ray diffraction) and Raman spectroscopy. Further, the optical properties are investigated through reflectance spectroscopy and PL (photoluminescence) spectroscopy.The emission spectroscopy in the visible regime confirms the presence of 2.1 eV emission.The TRUS measurements confirm the confinement of the charge carriers at 33 nm SnTe film w. r.t 275 nm SnTe.The indium dopant films show the presence of a metastable state which is absent in SnTe.This state resembles the resonant state at 0.82 eV and eventually can be tuned to various optoelectronic applications.