Effect of Ag doping on structural, optical and electrical properties of antimony sulfide thin films

This work reveals the effect of silver doping on structural, optical and electrical properties of Sb2S3 films grown by a citrate-mediated chemical bath deposition technique. The silver content in solution was 7.5 mol% with respect to Sb3+ ions. The films were deposited in a cold bath for four hours and subjected to thermal treatment in a N-2 atmosphere at 300 A degrees C for 1 h. Polycrystalline nature of Sb2S3 films with orthorhombic phase was confirmed in both undoped and Ag-doped samples by X-ray diffraction technique and Raman spectroscopy. Scanning electron microscopy imaging showed the presence of irregular-shaped interconnected particulate grains in the undoped films, while nearly spherical clusters of smaller grain size were observed for Ag-doped Sb2S3 films. X-ray photoelectron spectroscopy results revealed the incorporation of metallic Ag into the Sb2S3 lattice. A detailed growth mechanism has been proposed for the formation of Sb2S3 and incorporation of metallic silver in the host matrix. The optical properties were recorded by UV-Vis diffuse reflectance spectroscopy. The inclusion of Ag in Sb2S3 films causes a red shift in band gap values from 1.75 to 1.66 eV. The dark resistivity of Sb2S3 films was decreased by one order on silver doping.