Laser Ablation Synthesis of Tin Oxide Nanoparticles and Their Thin-Film Properties

Nanoparticles of tin oxide were hydrothermal synthesized by laser ablation in liquid using a Q-switched Nd:YAG laser at 1064 nm with energies ranging between 500 and 1000 mJ and temperature of 34 °C. The colloidal solutions obtained were drop mounted onto cleaned glass substrates to form thin films reaching ca. 200 nm thicknesses. The prepared films have been systematically studied with structural, morphological and optical features. The X-ray diffraction (XRD) characterization revealed the formation of polycrystalline tin oxide with a tetragonal crystal phase which mainly corresponds to the thermodynamically soluble SnO₂. A size of crystallite has been estimated by using Scherrer equation showing the dependence on laser energy. AFM analysis indicated that surface roughness and grain size decreased with increasing laser energy, which contributed to better surface uniformity. UV–Vis spectroscopy showed both improved optical absorption and a decrease of the optical band gap with increasing laser energy, attributed to defect induced localized states as well as band tailing effects rather than due to increased ordering. These findings underline the strong influence of the laser power on the structural and optical characteristics of tin oxide thin films for optoelectronic devices.