Vacuum 82 (2008) 39–44 Structural damage studies in conducting indium-tin oxide (ITO) thin films induced by Au 8+ swift heavy ions (SHI) irradiation N.G. Deshpande a , A.A. Sagade a , S.D. Chavhan a , J.C. Vyas b , F. Singh c , A.K. Tripathi c , D.K. Avasthi c , Ramphal Sharma a,Ã a Thin Film and Nanotechnology Laboratory, Department of Physics, Dr. Babasaheb Ambedkar Marathwada University, Aurangabad 431004, Maharashtra, India b Technical Physics and Prototype Engineering Division, Bhabha Atomic Research Center, Trombay, Mumbai 400085, India c Inter University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110067, India Received 22 November 2006; received in revised form 1 March 2007; accepted 18 March 2007 Abstract Spray pyrolysis deposited indium-tin oxide (ITO) thin films were fabricated and irradiated using Au 8+ swift heavy ions (SHI) (100 MeV energy), at different fluency doses ranging between 1  10 11 ions/cm 2 and 1  10 13 ions/cm 2 . After irradiation, significant changes have been observed in surface morphology and crystallographic structure pertaining to increase in grain size, change in surface roughness, crystallographic disorders of large crystallites, and noticed a net decrease in optical transmittance and electrical resistivity of these films. r 2007 Elsevier Ltd. All rights reserved. Keywords: Spray pyrolysis technique; Indium-tin oxide (ITO); Swift heavy ions (SHI) irradiation and structural damages 1. Introduction Indium-tin oxide (ITO) shows high electrical conductiv- ity and high optical transparency. Thin films of ITO are known as a transparent electrode and now widely used in electronic and/or opto-electronic devices including flat panel displays and solar cells [1]. The ITO thin films may be prepared using various techniques such as improved spray CVD [2], thermal decomposition of complex metal salts [3], rf sputtering from oxide targets [4], vacuum deposition [5], spray pyrolysis (SP) [6], etc. Among these processes, SP is very simple and potentially suitable technique for large area deposition of these films. In present investigation, we prepared ITO thin films using SP technique. In this technique, during film deposition the substrate temperature plays an important role, affecting the structural and opto-electronic properties of the grown films. The substrate temperature was optimized to get good quality films, i.e., having low electrical resistivity and high optical transmittance. Subsequently, these ITO films were irradiated by SHI at different fluency doses ranging between 1  10 11 ions/cm 2 and 1  10 13 ions/cm 2 and changes in structural, optical and electrical properties were studied with the ion energy/fluency. Low energy irradiation or ion implantation technique [7] (comprises of controlled deposition of impurity atoms in a pre-selected depth region at well-defined concentrations, and the process) is used for electrical and optical doping of semiconductors as well as for the synthesis of buried compound layers. However, energetic ion beam offer much boarder range of possibi- lities compared to the ion implantation, to modify the structure and properties of materials [8], caused by the very high local energy density deposited into the solid along the ion path. In fact, the energy loss of swift heavy ions (SHI) may be up to some tens of keV/nm, which results in a very short (some hundreds of picoseconds), very local (a cylinder of approximately 10 nm in diameter) and very high (some 0.1 eV/atom) excitation of the solid [9]. Under such extreme conditions, highly non-equilibrium processes ARTICLE IN PRESS www.elsevier.com/locate/vacuum 0042-207X/$ - see front matter r 2007 Elsevier Ltd. All rights reserved. doi:10.1016/j.vacuum.2007.03.004 Ã Corresponding author. E-mail address: ramphalsharma@yahoo.com (R. Sharma).