Structural and optical characterization of ZrOSub

Authors: Alireza Hojabri

Publish Date: 2016/04/16

Volume: 10, Issue: 3, Pages: 219-224

PDF Link

Abstract

Zirconium oxide thin films were grown successfully by thermal annealing of zirconium thin films deposited on quartz and silicon substrates by direct current magnetron sputtering technique The structural and optical properties in relation to thermal annealing times were investigated The Xray diffraction patterns revealed that structure of films changes from amorphous to crystalline by increase of annealing times in range 60–240 min The composition of films was determined by Rutherford back scattering spectroscopy Atomic force microscopy results exhibited that surface morphology and roughness of films depend on the annealing time The refractive index of the films was calculated using Swanepoel’s method The optical band gap energy of annealed films decreased from 550 to 534 eV with increasing thermal annealing timeZirconia thin films ZrO2 are one of the transitionmetal oxides with outstanding physical optical and chemical properties 1 2 3 4 5 6 7 8 9 10 11 12 13 14 including high hardness low electrical conductivity high melting point good thermodynamic stability in contact with silicon transparency in the visible and nearinfrared region high refractive index high dielectric constant and large optical band gap 2 10 11 Through having such properties ZrO2 thin films have attracted a lot of attention and applied in diverse field such as optical filters 5 memory device 6 it is also used as a material to store capacitors 7 in dynamic random access memories Such wide range of important applications has motivated researchers into growing ZrO2 thin films on different substrates by a variety of techniques Balakrishnan et al 8 fabricated ZrO2 thin films on silicon substrate at different oxygen partial pressure by pulsed laser deposition Shen et al 10 were employed electron beam evaporation technique to prepare ZrO2 thin films Rebib et al 11 have studied the structural and optical properties of zirconia thin films deposited by sputtering a ZrO2 target under an argon–oxygen gas mixture and different total gas pressures The sol–gel dip coating method was used for the preparation of highly transparent nanocrystalline zirconia thin films by Joy et al 12 RF sputtering deposition was employed by Yildiz et al 13 for preparation of nanocrystalline zirconia thin films with high transparency In this investigation nanocrystalline zirconia thin films were prepared by thermal annealing of zirconium Zr thin films grown on silicon and quartz substrates by DC magnetron sputtering As the structural and optical properties of thin films can be affected by some factors such as the growth method the deposition conditions and thermal annealing this investigation focuses on the influence of annealing time on structural and optical characteristics of ZrO2 thin filmsIn the present experiment firstly the zirconium Zr thin films were grown on silicon and quartz substrates by DC magnetron sputtering from a zirconium target purity 99999  The deposition chamber was initially evacuated to achieve a base pressure of 53 × 10−5 torr by means of a rotary and diffusion pumps After introducing argon gas as working gas the total pressure was kept constant at 53 × 10−2 torr Silicon and quartz substrates were first cleaned using ultrasonic bath for 15 min in acetone and ethanol Then deposition process was performed for 2 min for all films After that the prepared films were annealed in an electrical furnace at 450 °C for 60–240 min under the oxygen atmosphere The effect of annealing time on the structural morphological and optical properties of ZrO2 thin films were studied by different analyzing method The crystal structure of the films were characterized by Xray diffraction XRD Philips pw 1800 using Cu Kα radiation λ = 01506 nm at 40 kV and 30 mA in the 2θ scan range from 10 to 60 The morphology of prepared thin films was studied by atomic force microscopic AFM park Scientific Instrument Auto probe cp USA and the transmittance spectra of the annealed films were recorded using a spectrophotometer CARY 500 Scan The composition of films were determined by Rutherford back scattering spectroscopy RBS 15 using a 2 MeV proton beam of a 3 MV singleended Van de Graaff machine The scattered particles were measured by a surface barrier detector at 165° Numerical analysis of the collected data was performed via the SIMNRA simulation package

Keywords: