Influence of post heat treatment to the properties of ZnO thin film prepared by RF magnetron sputtering N.D. Md Sin 1, * 1 NANO-ElecTronic Centre, Faculty of Electrical Engineering, Universiti Teknologi MARA (UiTM), 40450 Shah Alam, Selangor, Malaysia *e-mail: nordiyana86@yahoo.com, Abdul Aziz. A 1 , S. Ahmad 1 , M.Z. Musa 1 , M.H. Mamat 1 , M. Rusop 1,2, * 2 NANO- SciTech Centre (NST), Institute of Science (IOS), Universiti Teknologi MARA (UiTM), 40450 Shah Alam, Selangor, Malaysia *e-mail: rusop@salam.uitm.edu.my Abstract— The influence of post heat treatment on ZnO thin films prepared by RF magnetron sputtering was reported. The effect of ZnO thin films post heat treatment were varies from 300°C to 550°C had been investigated. The thin films were examined using two point probe current-voltage (I-V) measurement (Keithley 2400), UV-Vis-NIR spectrophotometer, field emission scanning electron microscopy (FESEM) (JEOL JSM 7600F). The current- voltage (I-V) measurements indicated that the conductivity of post heat treatment temperature of 500°C give the optimum conductivity. All films exhibited high UV absorption (300~380nm) properties and had low absorbance in visible and near infrared (IR) (380~1200nm) region that obtained from UV- Vis-NIR spectrophotometer measurement. The observed image from FESEM shows an increase of the nanocolumnar size, as the post heat treatment increases. Keywords-component; ZnO thin films; post heat treatment; electrical properties; optical properties; structural properties I. INTRODUCTION The potential of Zinc oxide (ZnO) material has been extremely investigated by many researchers with its ability to use for various applications such as such as optoelectronic, electronic devices and solar cell. ZnO is n-type material semiconductor with wide band gap 3.37 eV and 60 meV of free exciton binding energy at room temperature [1]. ZnO is highly conductive material and high meting temperature. It has fabricated for various device application including solar cell[2], sensor[3] and optoelectronic devices[4]. Several of deposition method has been develop to deposit ZnO thin film such chemical vapour deposition (CVD) [5], sol-gel method[6], sputtering[7], hydrothermal[8] and pulse laser deposition (PLD) [9]. R.F magnetron sputtering are use to provide a uniform deposition, excellent in adhesion, highly crystalline, repeatability, and high quality thin with high quantity [10-12]. Various parameters must be studied in order to achieve required application such as substrate temperature, RF power, based pressure, ratio of gas and thickness. Post annealing process or post heating treatment is a process modifying the defect to enhance the electrical, optical and structural properties[13-14]. In this paper ZnO films were deposited by RF magnetron sputtering at 500°C on glass substrates and it’s were post heat treatment at different temperature in order to advance the properties of film. The influence of post heat treatment to the films on the electrical, optical and structural properties of ZnO has been presented. II. METHODOLOGY A. Deposition by RF magnetron sputtering ZnO thin films were deposited on glass substrates by R.F magnetron sputtering. The sputter with ZnO target (99.999%) was pump at 0.5mPa using a turbo molecular pump and the gas were injected with argon and oxygen at 45 and 5 sccm respectively. The pressure of the system was set to 7mTorr and rf power at 200 watt. The substrate temperature was maintained at 500°C during deposition. The deposition process was taken for 1 h. The ZnO thin films was annealed in ambient for 1h at different annealing temperature 300 o C, 350 o C, 400 o C, 450 o C, 500 o C and 550 o C. B. Characterization The electrical and optical properties of the thin film were characterized using 2 probes I-V measurement system and UV- Vis spectrophotometer respectively. The structural properties were characterized using FESEM. The thicknesses of the sample were measured using surface profiler (Dektak 150+). The thickness of all samples is shown in Table 1. III. RESULTS AND DISCUSSIONS A. Electrical properties Fig. 1 shows the I-V measurement of ZnO thin films at different post heat treatment temperature. The sample were measured with voltage varied from -10V to 10V. All thin films exhibit ohmic behaviour with Au metal contact. The current density shows the highest at post heat treatment temperature 500°C. Fig. 2 shows the film conductivity and resistivity of ZnO thin films at different post heat treatment temperature. The resistivity and conductivity of the thin film was obtained using equation (1) and (2) respectively [15]: 978-1-4673-5160-7/12/$26.00 ©2012 IEEE S3-1 2012 IEEE Student Conference on Research and Development 88