INTRODUCTION In recent years, there has been a growing interest in the use of transparent conducting oxide thin films as transparent conducting layer in thin film solar cells 1,2 , heat reflectors and as various gas sensors 3-6 . Tin oxide is the first transparent conductor to have received significant commercialization 1,7 . Among the different transparent conductive oxides, SnO 2 (TO) films seem to be the most appropriate for use in solar cells, owing to its low electrical resistivity (10 -3 Ω cm) and high optical transmittance (90 %). Tin oxide is wide band gap (~4 eV) and indirect band gap (of about 2.6 eV) non-stoichiometric semiconductor 8 . Also, SnO 2 is chemically inert, mechanically hard and can resist high temperature 1 . The physical properties of SnO 2 films can be enhanced by doping with appropriate doping such as antimony (Sb), indium (In) and fluorine (F) 9,10 . Doped or undoped SnO 2 thin films can be synthesized by numerous techniques such as chemical vapour deposition (CVD) 11 , sputte- ring 12 , sol-gel process 13 , spray pyrolysis 14,15 , hydrothermal method 16 and pulsed laser deposition 17 . Among the various deposition techniques the spray pyrolysis is the well suited for the preparation of doped tin oxide thin films because of its simple and inexpensive experimental arrangement, ease of adding various doping material, reproducibility, high growth rate and mass production capability for uniform large area coatings, which are desirable for industrial and solar cell applications 1,6,10 . Relationship Between the Doping Levels and Some Physical Properties of SnO 2 :Sb Thin Films Spray-Deposited on Optical Glass GÜVEN TURGUT * , DEMET TATAR and BAHATTIN DÜZGÜN Department of Physics, K.K. Education Faculty, Ataturk University, Erzurum 25240, Turkey *Corresponding author: Fax: +90 44 22369055; Tel: +90 44 22314011; E-mail: guventurgut@atauni.edu.tr (Received: 24 October 2011; Accepted: 20 July 2012) AJC-11856 SnO2:Sb thin films were prepared by the spray pyrolysis technique on optical micro slide glass at substrate temperature 793 (± 5) K. The relationship between the antimony doping level and the electrical, structural and optical properties of the films were investigated. The X-ray diffraction patterns showed that the films are polycrystalline. The grain size varies from 28.19 to 33.59 nm. Atomic force microscopic study revealed the surface of SnO2:Sb to be made of nanocrystalline particles. The electrical study has revealed that the films are degenerate and exhibit n-type electrical conductivity. The SnO2:Sb films had a minimum resistivity of 0.28 × 10 -4 Ω cm, maximum carrier density of 37.6 × 10 19 cm -3 and mobility of 590 cm 2 /V.s. The sprayed SnO2:Sb film having minimum sheet resistance of 0.17 Ω/cm 2 , highest figure of merit of 135 × 10 -4 Ω -1 at 550 nm. The sheet resistance attained for the doped film in this study has been lower than the values reported for 2 wt % antimony doped tin oxide films prepared from aqueous solution of SnCl2·2H2O precursor. The obtained results revealed that the structures and properties of the films were greatly affected by doping levels. Key Words: SnO2: Sb; X-ray diffraction, Spray pyrolysis, Thin films. In the present work, SnO2:Sb thin films have been prepared by the spray pyrolysis (SP) technique at substrate temperature of 793 K using dehydrate stannous chloride (SnCl2.2H2O with 98 % purity, Merck) and antimony trichloride (SbCl3 with 99 % purity, Merck) as precursors. The aim of this work is to study the relationship between the doping levels and some physical properties of SnO2:Sb thin films such as the electrical and structural properties. The results obtained has been compared and discussed with the specified results by several researchers. EXPERIMENTAL The antimony doped tin oxide thin films reported in the present study were prepared using a homemade spray pyrolysis apparatus. The normalized distance between the spray nozzle and the substrate is 40 cm the spray angle (α) is 45º. The optimization was conducted by taking different sets of read- ings, keeping the nozzle to substrate distance as 25, 30, 35, 40 and 45 cm. A schematic diagram of this set-up and a detailed description of the deposition process have been given in Fig. 1. Thin films of SnO 2 :Sb (ATO) were deposited on optical glass substrate (75 × 25 × 1 mm 3 ) by spray pyrolysis technique. Stannous chloride (SnCl 2 .2H 2 O with 98 % purity, Merck) was used in making the precursor solution for SnO 2 thin films. Though SnCl 2 .2H 2 O can partly ionize into Sn 2+ and Cl – , it could Asian Journal of Chemistry; Vol. 25, No. 1 (2013), 245-250 http://dx.doi.org/10.14233/ajchem.2013.12919