Study of spin coated high antimony content Sn–Sb oxide films on silica glass

Antimony doped tin oxide (ATO) films of 326–1714 ± 3Å physical thickness were deposited onto silica glass substrate by the sol–gel spinning technique. The chosen atomic ratios of Sn:Sb was varied as 90:10, 70:30, 50:50 and 30:70. Nanostructured surface feature was observed in the SEM micrographs of ATO films of 10 to 30 at.% Sb. The nanocluster size was dependent on antimony content. Cassiterite phase of SnO2 was observed at low content of Sb. The films were absorbing in the UV region. Two direct band gaps and one indirect band gap for each system were evaluated from their absorption spectra. The two direct band gap values were in the range, 3.73–5.20 eV while the indirect band gap values were in the range, 2.54–3.46 eV. In the case of single layer system, Moss–Burstein shift in both direct and indirect band gaps was observed with increase in at.% of Sb content. Electrical resistivity of the films was in the range, 1.19 × 10− 3 to 155.59 × 10− 3 Ω cm. Minimum resistivity was obtained for 30 at.% Sb. Transmissivity of the films in the visible region was in the range, 80–97%. Total thermal emissivity (λ range, 5.0–20.0 μm) values were in the range 0.78–0.86.