Physicochemical Properties of SnTe Thin Films Dependent on Compositional Ratios

Abstract

This study introduces physicochemical properties based on the compositional ratio of the SnTe thin films (TFs) fabricated by radio frequency (RF) magnetron cosputtering. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) results show that the grain sizes decrease with increasing Te content, with pure Te TFs yielding the lowest Rq value (root mean square value of roughness) of 0.76 nm. Contact angle (CA) measurements show that pure Te TFs pertain to the highest total surface free energy. X‐Ray diffraction (XRD) patterns strongly indicate that pure Te TFs exhibit a hexagonal crystal structure and pure Sn TFs exhibit a tetragonal crystal structure. The dominant oxide species on the surface is TeO2 for Te‐rich films, which is deduced by X‐Ray photoelectron spectroscopy (XPS) results. Pure Te TFs yield a work function value of 4.88 eV when measured with ultraviolet photoelectron spectroscopy (UPS) and 5.46 eV when measured with a Kelvin probe. SnTe TFs with 70% Te content exhibit the lowest electrical conductivity among the fabricated TFs.