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
OPTICAL PROPERTIES OF NANOSTRUCTURED CERIUM OXIDE THIN FILMS BY PULSED LASER DEPOSITION K. Maniammal#, Navas I*, R.Vinod kumar*, K.M. Nissamudeen*, Dr. K.G. Gopchandran*, Dr.V. Biju# #Dept of Physics, University of Kerala Thiruvananthapuram, Kerala, India *Dept of Optoelectronics, University of Kerala, Thiruvananthapuram, Kerala, India
-----------------------------------------------------------------***-------------------------------------------------------------Abstract- Cerium oxide (CeO2) thin films have been prepared by using Pulsed laser deposition (PLD) technique onto the quartz substrate at a pressure of about pO2– 2x10-3 mbar. The films were characterized using X-ray diffraction and UV-Visible spectroscopy techniques. The optical properties of cerium oxide films were studied in the wavelength range of 190 – 900 nm. The film was highly transparent in the visible region. It is also observed that the film has low reflectance in the ultra-violet region. The optical band gap of the film is determined and is found to decrease with the increase of film thickness. The X-ray diffraction of the film showed that the film is overcoming its amorphous nature to crystalline.
laser ablation technique. If the back ground oxygen pressure exceeds this value, the quality of the film may deteriorate owing to the enhanced collision of laser plume species with background oxygen atoms. In this work the structural and optical characteristics of CeO2 thin films prepared using PLD. This is a useful physical vapor deposition technique to deposit materials with high melting points. Various characterization tools have been employed to rationalize the significance of this work. Structure identification of the films has been made by X-ray diffraction technique. Scanning electron microscopy has been employed to analyze the surface morphology of the samples. Linear optical studies include UV-VIS absorption spectroscopy. An attempt has also been made to find out the thickness of the films. The particular ability of laser deposition to grow films in reactive environments (like oxygen), makes it well suitable for applications.
Keywords: On axis Pulsed laser deposition, X-ray diffraction, amorphous nature I.
Introduction
The recent surge of activity in the wide band gap semiconductors has arisen from the need for optical materials, especially emitters, which are active in the blue and UV wavelength. The extensive research activities carried out on material to realize optical devices because of its high refractive index and good transmittance in the visible spectrum.
2. Experimental Details The deposition of the films is carried out inside a multiport stainless steel vacuum chamber equipped with a gas inlet, a rotating multi-target and a substrate holder which can be heated up to 1073 K. The irradiations were performed using a Q-switched Nd:YAG laser (Quanta– Ray INDI–Series, Spectra Physics) with 90 mJ of laser energy at frequency doubled 532 nm radiation with pulse width 8ns and repetition frequency 10 Hz. CeO2 (Merck, purity 99.995%) powder is grinded well in an agate mortar for 2 h, pressed into 11mm diameter and 3mm thickness pellet at 1.5 ton and then sintered at 1350 8C for 9 hour in air. Sintered CeO2 pellets are used for ablation on quartz substrates. Before irradiations, the deposition chamber is evacuated down to a base pressure of ~10-6 mbar. The energy density of the laser beam at the target surface was maintained at 1 J/cm2. The laser radiation is impinging on the target at 458 with respect to the normal. The depositions of the films are done on quartz substrates kept at an on-axis distance of 65 mm. The target is rotated with constant speed during
CeO2, revealed its potential applications in optoelectronics. Cerium oxide (ceria) films have received considerable interest because of their high transparency in the visible and near IR region and electro-optical performance [1-4]. Rare earth oxides are potentially useful materials for various optical and electronic applications (e.g. optical filters, capacitors). CeO2 is an interesting. In the present study thin CeO2 films have been deposited on a quartz substrate at room temperature, giving substrate heating at temperatures of 303, 523, and 923 K and the oxygen partial pressure 2x 10-3 mbar was introduced at 8x10-6 mbar of vacuum, using pulsed
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