Physical properties of sprayed antimony doped tin oxide thin films: The role of thickness

Transparent conducting antimony doped tin oxide (Sb:SnO₂) thin films have been deposited onto preheated glass substrates using a spray pyrolysis technique by varying the quantity of spraying solution. The structural, morphological, X-ray photoelectron spectroscopy, optical, photoluminescence and electrical properties of these films have been studied. It is found that the films are polycrystalline in nature with a tetragonal crystal structure having orientation along the (211) and (112) planes. Polyhedrons like grains appear in the FE-SEM images. The average grain size increases with increasing spraying quantity. The compositional analysis and electronic behaviour of Sb:SnO₂ thin films were studied using X-ray photoelectron spectroscopy. The binding energy of Sn3d_5/2 for all samples shows the Sn⁴⁺ bonding state from SnO₂. An intensive violet luminescence peak near 395 nm is observed at room temperature due to oxygen vacancies or donor levels formed by Sb⁵⁺ ions. The film deposited with 20 cc solution shows 70 % transmittance at 550 nm leading to the highest figure of merit (2.11 × 10⁻³Ω⁻¹). The resistivity and carrier concentration vary over 1.22 × 10⁻³ to 0.89 × 10⁻³Ω·cm and 5.19 × 10²⁰ to 8.52 × 10²⁰ cm⁻³, respectively.