Tin Sulfide Thin Films by Pulse Electrodeposition: Structural, Morphological, and Optical Properties

Abstract

Tin sulfide thin films, typically 350 nm thick, were deposited on SnO 2:F -coated transparent conductive oxide glass substrates by pulse electrodeposition. The applied potentials were Von =-0.9 V and V off =0.1 V vs saturated calomel electrode with pulse on/off durations of 10 s. The films crystallized in the orthorhombic structure corresponding to SnS (herzenbergite), with grain size varying in the range from a few nanometers to more than 100 nm. X-ray diffraction analysis shows an average size of 12 nm; however, scanning electron microscopy and transmission electron microscopy images show the presence of large crystallites with well-developed facets along with agglomerations of smaller crystallites. Estimation of the bandgap from the optical spectra of these films showed absorption due to direct transition occurring at 1.3 eV. Elemental compositions of these SnS samples determined using energy dispersive X-ray spectroscopy were 51.4 and 48.5%, respectively, for Sn and S. Raman spectra suggested the presence of traces of Sn2 S3 and SnS2. The surface analysis by X-ray photoelectron spectroscopy showed the presence of traces of metallic Sn. The films are photosensitive with a dark resistivity 106 ω cm. © 2010 The Electrochemical Society.