Giant Seebeck coefficient in SnTe thin films grown by thermal evaporation using layered structure engineering

Abstract

In this work, we have reported a giant Seebeck coefficient (8033 µV/K) in SnTe thin films by controlling the layered structure using post growth annealing technique. The samples used in the current study were synthesized using a vacuum tube furnace having an evaporation temperature 700 °C, base pressure 180 m Torr and source to substrate distance 7 cm. Sn and Te metal powders with an equal weight ratio were evaporated on the glass substrate to form SnTe composite. Post-growth annealing in vacuum environment was performed for different time’s duration of 1–4 h with a step of one hour. XRD analysis reveals six diffraction peaks for all samples, which correspond to different crystal planes of SnTe structure. Raman spectra exhibit the presence of specific vibrational modes associated with SnTe. Using the giant value of Seebeck coefficient and moderate electrical conductivity, a strong power factor value of 8.1 × 10−3 W m−1 K−2 was observed for optimized sample (annealed for 3 h). The strongest values of Seebeck coefficient and power factor are supposed to be the layered structure of SnTe thin films which was verified by the SEM images.