Molar Concentration Effects on the Optical and Structural Properties of Nanostructural SnO₂ Thin Films

Abstract

Thin films of nanostructured SnO2 with different molariteswere prepared by chemical spray pyrolysis technique. XRD analysis reveals that all the films were tetragonal polycrystalline with a preferred orientation along (110) plane. AFM measurements indicate that the value of the grain size for 0.05 M, 0.1 M and 0.15 M were 111nm, 78 nm and 58 nm respectively. SEM micrograph proved the existence of small cracks on the film surface, EDS confirmed the composition percentage ratio of Sn and O­2 and no trace of impurities could be detected. PL spectra gives the indication about optical energy gap and the effect of concentration on it which appeared as a blue shift. The transmittance was studied for the deposited thin films, identifying that the transmittance decreases by the increase in molarity. The value of the optical energy gap of the deposited thin films was increased upon increasing molar concentration due o quantum confinement effect. The Urbach energy was also studied, their values decrease as the molar concentration increase.