Effect of Trap States in Carrier Transport and Photoconductivity Studies of WSe<SUB>2</SUB>/MoS<SUB>2</SUB> Nanocomposite Thin Films
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We investigated the temperature-dependent electrical transport and photoconductivity studies of WSe2/MoS2 nanocomposite thin films. The thin film of ~ 150 nm has been deposited using the thermal evaporation method and characterized using X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and field emission scanning electron microscopy (FESEM) with elemental mapping. We have analyzed three types of carrier transport mechanism – Mott’s variable range hopping (VRH), nearest neighbor’s hopping (NNH), and thermally activated conduction in the temperature range of 150–350 K. Trap states in WSe2/MoS2 are significant in the formation of localized states which results in Mott’s VRH model (150–250 K). NNH and thermally activated conduction mechanism explained the electrical transport in the temperature range of 250-350 K. In photoconductivity studies, the role of defect/trap states in persistent photoconductivity, air and vacuum atmosphere has been studied to formulate a mechanism.