Structural, optical and electrical characterization of MoS2/TiO2 heterostructured thin films by chemical bath deposition technique

Abstract

MoS2/TiO2 heterostructures thin films are successfully deposited by chemical bath deposition (CBD) technique. The structural, optical and electrical properties of prepared films are characterized by X-ray diffraction (XRD), Raman spectroscopy, UV-vis spectrophotometry, photoluminescence spectroscopy (PL), and Four point probe technique, respectively. Raman Spectra and XRD confirmed the formation of hexagonal MoS2 and anatase TiO2. UV-Vis spectrophotometry confirmed the band gap energy (Eg) of MoS2 and TiO2 thin films are 1.14 eV and 3.44 eV, respectively. The Eg of films is changed according to the material deposited onto them i.e. it increased by depositing TiO2 onto the MoS2 and decreased the other way round. MT (Titania on Molybdenum disulfide) and TM (Vice Versa) have band gaps of 2.81 eV and 1.5 eV, respectively. The photoluminescence spectra showed that photoluminescence emission increased for TiO2 in the MoS2/TiO2 and TiO2/MoS2 heterostructures films. The exchange of trion to neutral excitons by charges transfer from MoS2 to TiO2 in heterostructures leads to increase the PL intensity. The average sheet resistivity of TiO2, MoS2, glass/MoS2/TiO2 and glass/TiO2/MoS2 films are 2.41 × 107 (Ω-m), 6.44 × 104 (Ω-m), 1.93 × 106 (Ω-m) and 2.35 × 104 (Ω-m), respectively. CBD is low cost, simple, and large area deposition technique and by this research the heterostructures films can easily be deposited for industrial purpose.