Effect of compositional ratio of Sn in SnZn thin films on morphological and chemical properties

Zinc (Zn) and tin (Sn) based alloy thin films have been of recent interest in the semiconductor industry. Despite such interest, knowledge on how the concentration of Sn affects the chemical, electrical, optical and surface properties SnZn thin films is still scarce. In this paper, SnZn thin films with varying ratios of Zn to Sn were fabricated through radio frequency (rf) magnetron sputtering. The resulting SnZn thin films were analyzed using scanning electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy (XPS), contact angle measurements, a 4-point probe, X-ray diffraction (XRD) patterns, and ultraviolet photoelectron spectroscopy (UPS). According to our results, The SnZn thin films that were fabricated using an rf power of 15 W to the Sn target had the roughest surface morphology and the films fabricated using an rf power of 10 W to the Sn target had the largest grain size. Contact angle measurements and 4 point probe measurements revealed that the SnZn were overall hydrophobic and the electrical conductivity increased with doping higher concentrations of Sn. XRD showed that SnZn thin films had larger grain sizes than pure Zn thin films. XPS and UPS analysis suggested the Fermi level was brought closer to the vacuum level when Sn was doped in Zn thin films.