International Research Journal of Engineering and Technology (IRJET)
e-ISSN: 2395-0056
Volume: 04 Special Issue: 09 | Sep -2017
p-ISSN: 2395-0072
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One Day International Seminar on Materials Science & Technology (ISMST 2017) 4th August 2017 Organized by
Department of Physics, Mother Teresa Women’s University, Kodaikanal, Tamilnadu, India
Structural and optical properties of electron beam evaporated ITO and Ni: ITO thin films Deepannita Chakraborty1, S. Kaleemulla2*, N. Madhusudhana Rao3, K. Subbaravamma4, G. Venugopal Rao5 1Thin
films Laboratory, School of Advanced Sciences, VIT University, Vellore-632014, Tamilnadu, India. Thin films Laboratory, Centre for Crystal Growth, VIT University, Vellore-632014, Tamilnadu, India. 3Department of Physics, VIT AP University, Amaravati-522237, Andhra Pradesh, Andhra Pradesh, INDIA 4Department of Physics, AMET University, Kanathur, Chennai - 603112, Tamilnadu, India. 5Materials Physics Division, Indira Gandhi Centre for Atomic Research, Kalpakkam-603102, Tamilnadu, Indiarst ---------------------------------------------------------------------***--------------------------------------------------------------------2
Abstract - Indium-tin-oxide (ITO) and Ni doped ITO thin
gas sensors, flat panel displays, etc [6-10]. Much interest has been shown on the optical and electrical properties of ITO thin films using different preparation techniques, doping with different impurities. In addition to the optical and electrical properties of ITO, if magnetic properties were also added for this, then it can find new future applications such as spintronics in which one can utilize both charge and spin of electron. Till now few reports are available on magnetic properties of ITO thin films [11,12]. Hence an attempt is made here for the preparation of ITO and Ni doped ITO thin films using electron beam evaporation technique and studied their structural and optical properties.
films were prepared using electron beam evaporation technique. The prepared thin films were subjected to structural and optical properties. From the XRD it was observed that the films were crystalline in nature with cubic structure. The crystallite size was calculated using Scherrer’s relation and found that it was about 25 nm. The optical transmittance and absorbance spectra were recorded using UV-Vis-NIR spectrophotometer. From these the optical band gap of ITO and Ni:ITO thin films were found to be 4.0 eV and 3.97 eV, respectively. The Fourier transform-Infrared spectroscopy studies showed peaks at 292, 519, 804, 957, 1149, 1387 and 2985 cm-1 which are characteristic of In-O bonds.
2. EXPERIMENTAL DETAILS The ITO and Ni doped ITO source materials were prepared using solid state reaction and studied their physical properties [13]. The same powder samples were taken here as source materials to prepare the ITO and Ni: ITO thin films. The films were prepared using electron beam evaporation technique [12A4D]. A base pressure of 5x10-6 mbar was created before coating the films. A pressure of 5x10-5 mbar was maintained during the deposition. A well cleaned glass substrates were used here as substrate for coating the films. The substrates were cleaned as per the protocol and fixed onto the substrate holder. The total set up was kept in coating unit and the substrate temperature was raised to 350° C and maintained the same temperature till the end of the coating. The coating was carried out for 30 min. The thicknesses of the films were controlled by quartz crystal thickness monitor (QTM) and it was about 250 nm. X-ray diffraction (X-ray diffractometer, D8 Advance, BRUKER) was used to establish structural aspects. Energy dispersive analysis spectroscopy (EDS) (OXFORD instrument incapenta FET X3) was used to carry out elemental analysis. The diffused reflectance spectra were recorded on UV-Vis-NIR Spectrophotometer (JASCO V-670). Fourier Transform
Key Words: Dilute magnetic semiconductors, thin films, electron beam evaporation, shallow donors, direct band gap.
1. INTRODUCTION Currently much focus is being paid on physical properties of oxide semiconductors such as ZnO, SnO2, In2O3, Cu2O, CdO, TiO2, etc [1-3]. These oxide semiconductors exhibit two most important properties such as high optical transmittance in the visible region and high electrical conductivity [4,5]. Among the other oxide semiconductors, indium oxide is one of the best suited materials for most of the optoelectronic applications. It is a wide band gap oxide semiconductor (3.7 eV) with cubic structure. It exhibits conductivity equal to that n-type semiconductor. The electrical conductivity of this material can be controlled by controlling the oxygen vacancies in the host lattice or by doping with suitable element. In this contest tin (Sn) is the most suitable element to be doped into the In2O3 lattice to bring the changes in optical and electrical properties. The indium-tin-oxide called as ITO is the promising material for optoelectronic applications such as solar cell, touch screens,
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