Synthesis and characterization of indium doped tin oxide by using Flame spray pyrolysis

Synthesis of high performance p-type transparent conducting oxides has become important in the context of thin film transistors. Tin oxide is a promising material for p-type conductivity by various dopants like Li, Al, In and N. In this study, nanocrystalline indium doped tin oxide powders were synthesized by Flame spray pyrolysis (FSP) from inorganic precursors. Two batches of samples with systematically varying indium concentrations from 2 to 50 mole percent were prepared. X-ray diffraction was carried out to confirm the cassiterite structure of SnO₂. Above 30 mole percent In concentration, peaks corresponding to cubic In₂O₃ were observed. The change in crystallite size with the dopant level was determined. HRSEM and HRTEM analysis of micrographs show the presence of elongated tin oxide nanoparticles ranging from 5 to 50 nm and show a high degree of crystallinity. The optical transmittance of the powders was measured using UV-Vis DRS and the optical band gap values were calculated using the Tauc realtion. XPS confirmed the presence of indium in the doped samples.