Optics & Laser Technology 40 (2008) 247–251 Effects of deposition temperature on the structural and morphological properties of thin ZnO films fabricated by pulsed laser deposition Rakhi Khandelwal a , Amit Pratap Singh a , Avinashi Kapoor a,Ã , Sorin Grigorescu b , Paola Miglietta c , Nadya Evgenieva Stankova d , Alessio Perrone c a Department of Electronic Science, University of Delhi South Campus, New Delhi 110021, India b Laser Department, National Institute for Lasers, Plasma and Radiation Physics, P.O. Box MG-36, Bucharest-Magurele RO-77125, Romania c Physics Department and INFN, University of Salento, 73100 Lecce, Italy d Institute of Electronics, Bulgarian Academy of Sciences, 1784 Sofia, Bulgaria Received 11 December 2006; received in revised form 18 April 2007; accepted 19 April 2007 Available online 29 June 2007 Abstract ZnO thin films were grown on Si(1 0 0) substrates using pulsed laser deposition in O 2 gas ambient (10 Pa) and at different substrate temperatures (25, 150, 300 and 400 1C). The influence of the substrate temperature on the structural and morphological properties of the films was investigated using XRD, AFM and SEM. At substrate temperature of T ¼ 150 1C, a good quality ZnO film was fabricated that exhibits an average grain size of 15.1 nm with an average RMS roughness of 3.4 nm. The refractive index and the thickness of the thin films determined by the ellipsometry data are also presented and discussed. r 2007 Elsevier Ltd. All rights reserved. PACS: 68.55.a; 81.15.z; 81.16.Mk Keywords: ZnO thin films; Si substrate; Pulsed laser deposition 1. Introduction In recent years, ZnO-based materials have been used in many kinds of applications related to microelectronics, sensors and optoelectronics field. ZnO is a promising candidate for such applications due to its low toxicity, high stability, high transparency in the visible wavelength range and low electric resistance [1–3]. It is a wide band gap semiconductor material with a direct energy gap of about 3.37 eV. ZnO absorbs UV radiation due to band to band transitions [4]. ZnO films are c-axis oriented and can be easily fabricated in various kind of substrate materials, e.g. Si, GaAs, etc. Different deposition techniques are used to prepare ZnO thin films such as pulsed laser deposition (PLD), chemical vapour deposition, magnetron sputtering, sol–gel proces- sing, etc. [5–8]. PLD offers many advantages compared with other techniques: reduced contamination due to the use of laser light, control of the composition of deposited structure and in situ doping. To get the maximum utilization of these films, the fabrication of good quality films at comparatively low temperature is desired. In this paper, we report the results on the deposition of ZnO thin films obtained at different substrate temperatures by PLD technique. We also investigated the influence of the substrate temperature applied during the deposition process on the structural and morphological properties of the films. 2. Experimental details Preparation of the thin films was carried out by a typical PLD high vacuum system [9]. Before each deposition event, the vacuum chamber was evacuated to a residual pressure ARTICLE IN PRESS www.elsevier.com/locate/optlastec 0030-3992/$ - see front matter r 2007 Elsevier Ltd. All rights reserved. doi:10.1016/j.optlastec.2007.04.011 Ã Corresponding author. Tel.: +91 935 0571397; fax: +91 241 10606. E-mail address: avinashi_kapoor@yahoo.com (A. Kapoor).