XPS study of iodine and tin doped Sb2S3 nanostructures affected by non-uniform charging

X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) measurements are used for investigating incorporation of iodine and tin into the stibnite (Sb2S3) lattice, as well as for determining surface composition and structure, respectively. The XRD analysis revealed the visible presence of a single phase, that of pure orthorhombic Sb2S3 structure. XPS survey spectra confirmed the presence of expected elements (Sb, S, Sn and I) at the surface of corresponding samples. Since the bonding identification was hindered by non-uniform charging of samples during acquiring the photoelectron spectra, a novel approach for the analysis of high resolution spectra was proposed and successfully implemented. XPS results showed that surface composition of the nondoped sample coincides with that of the bulk, while doping strongly affects surface of the samples. Sn-doped sample appears to be prone to surface oxidation. The presence of Sb2S3, Sb2O3, SnS2 and Sn(0) phases at the surface was revealed. Strong segregation of antimony was observed in the I-doped Sb2S3 sample. Iodine is also present at the surface in the form of the SbI3 phase, while the detected sulphur signal most probably corresponds to S atoms from unaltered deeper layers.