Vol.:(0123456789) 1 3 Applied Physics A (2018) 124:643 https://doi.org/10.1007/s00339-018-2065-8 Physical properties of nebulized spray pyrolysised SnO 2 thin films at different substrate temperature S. Palanichamy 1  · J. Raj Mohamed 2  · P. S. Satheesh Kumar 1  · S. Pandiarajan 3  · L. Amalraj 1 Received: 15 April 2018 / Accepted: 22 August 2018 © Springer-Verlag GmbH Germany, part of Springer Nature 2018 Abstract Using nebulized spray pyrolysis technique, we investigate tin oxide (SnO 2 ) thin films had been coated with different substrate temperature (300–500 °C) onto microscopic glass substrate. All the prepared films have tetragonal crystalline structure with preferential orientation (110) observed by X-ray diffraction analysis. The reduced strain due to the increase of substrate tem- perature from 300 to 450 °C increased the average crystalline size from 27.40 to 42.99 nm and then decreased further. All the films display high transmittance in the visible and also in IR region. As the substrate temperature had increased from 300 to 500 °C, the average transmittance of SnO 2 thin films varied between 79 and 90%. The energy band gap values had diminished from 3.91 to 3.75 eV by increasing the substrate temperature. The refractive index (n) of these films had increased from 2.11 to 2.32 with increase in substrate temperature from 300 to 450 °C and then decreased further. The optical static and high frequency dielectric constants (ε o and ε ∞ ) have been determined as a role of substrate temperature. The surface morphology of these thin films exhibited polyhedron-shaped grains obtained by scanning electron microscope. Energy dispersive X-ray analysis proved the presence of Sn and O elements in the as-prepared SnO 2 films. Hall effect measurements shows that the film had deposited at 450 °C exhibited lowest resistivity 6.53 × 10 −3 Ω cm and highest figure of merit 9.14 × 10 − 3 (Ω/sq) −1 among all the samples. Activation energy varied between 0.14 and 0.20 eV with the increase of substrate temperature from 300 to 500 °C. 1 Introduction Transparent conducting oxide (TCO) thin films such as zinc oxide (ZnO), tin oxide (SnO 2 ), indium oxide (In 2 O 3 ), cadmium oxide (CdO), titanium oxide (TiO 2 ) have been attracted substantial attention owing to their low resistivity and high transparency in the visible part of spectrum [1]. Among various transparent conducting oxides, SnO 2 is a most significant material since it is inexpensive, mechani- cally hard and thermally stable in oxidizing environments at high temperature, and splendid chemical stability [2]. Espe- cially, SnO 2 films are excellent adherence to numerous sub- strates, resistant to mechanical corrosion, and unchangeable at high temperature. At room temperature, it has fantabu- lous resistance to strengthen acids and bases [3]. SnO 2 thin film has a tetragonal structure with a large band gap (E g > 3.6 eV) n type semiconductor [4], which used in numerous applications like flat panel displays [5], super capacitor [6], organic light emitting diodes [7], heat mirror coatings [8] and solar cells [9]. Due to their remarkable chemical and physical characteristics, the preparation of ultra-fine SnO 2 particles is of magnificent technological and scientific pas- sion and their use as optoelectronic devices, catalysts for the oxidation of organic compounds in gas sensors and recharge- able Li-batteries [10], etc. Various types of techniques have been used to deposit SnO 2 thin films such as chemical vapour deposition [11], sol–gel technique [ 12], metal organic chemical vapour deposition (MOCVD) [13], photochemical method [14], pulse laser deposition [15], plasma-enhanced atomic layer deposition (PEALD) [ 16], Electron beam evaporation [17], magnetron sputtering [18] and spray pyrolysis [19], etc. Among these methods, the physical techniques are capable of depositing high quality and uniform thin films, they are comparably overpriced and tremendously energy * L. Amalraj amalraj57@yahoo.co.in 1 Research Department of Physics, V.H.N.S.N. College, Virudhunagar, Tamilnadu 626001, India 2 P.G. and Research Department of Physics, H.H. The Rajah’s College, Pudukkottai, Tamilnadu 622001, India 3 Department of Physics, Devanga Arts College, Aruppukottai, Tamilnadu 626101, India