Amorphous to crystalline transformation in Ta2O5 studied by Raman spectroscopy

Many of the interesting properties that make Ta2O5 a strategic material for current and future applications in chemistry, microelectronics and optics, depend on its structural characteristics. In this work, we use Raman spectroscopy to probe structural modifications in amorphous Ta2O5 coatings submitted to thermal annealing. On the basis of previous knowledge on the crystalline material, we perform Raman spectrum simulations in disordered and partially ordered Ta2O5 from a phonon density of states. Calculated spectra are in good agreement with complex experimental spectra. Our original approach allows assignment of the vibrational features of the amorphous material, and quantitative interpretation of observed structural modifications in terms of ordering scales. In addition, it provides numerical indicators to analyse amorphous to crystalline phase transformation. Copyright © 2012 John Wiley & Sons, Ltd.

[1]  R. Roth,et al.  Structural systematics in the binary system Ta2O5–WO3. V. The structure of the low-temperature form of tantalum oxide L-Ta2O5 , 1971 .

[2]  J. Zuo,et al.  A high-temperature structure for Ta2O5 with modulations by TiO2 substitution , 2006 .

[3]  M. Okada,et al.  Electrochromic switchable mirror foil with tantalum oxide thin film prepared by reactive DC magnetron sputtering in hydrogen-containing gas , 2011 .

[4]  A. Magnéli,et al.  On the Tantalum - Oxygen System. , 1952 .

[5]  J. Tominaga,et al.  Raman scattering study of the a-GeTe structure and possible mechanism for the amorphous to crystal transition , 2006, cond-mat/0602167.

[6]  H. Ono,et al.  Ta–O phonon peaks in tantalum oxide films on Si , 2001 .

[7]  Jianhua Huang,et al.  Preparation of mesoporous tantalum oxide and its enhanced photocatalytic activity , 2011 .

[8]  Yongfa Zhu,et al.  Preparation and performances of nanosized Ta2O5 powder photocatalyst , 2005 .

[9]  N. Terao.  Structure des Oxides de Tantale , 1967 .

[10]  Yizhou Song,et al.  Optical and structural properties of dense SiO2, Ta2O5 and Nb2O5 thin-films deposited by indirectly reactive sputtering technique , 2000 .

[11]  M. Fontana,et al.  Temperature dependence of the Raman modes in LiNbO 3 and mechanism of the phase transition , 1997 .

[12]  K. Geib,et al.  Effects of oxygen content on the optical properties of tantalum oxide films deposited by ion-beam sputtering. , 1985, Applied optics.

[13]  M. J. Kim,et al.  Comparision of residual stress and optical properties in Ta2O5 thin films deposited by single and dual ion beam sputtering , 2005 .

[14]  J. Autran,et al.  Tantalum pentoxide (Ta2O5) thin films for advanced dielectric applications , 1998 .

[15]  J. Leray,et al.  Use of carbon-free Ta2O5 thin-films as a gate insulator , 1997 .

[16]  Carl M. Lampert,et al.  Structural and optical properties of sol-gel deposited proton conducting Ta2O5 films , 1997 .

[17]  M. Audier,et al.  A very promising piezoelectric property of Ta2O5 thin films. I: Monoclinic–trigonal phase transition , 2011 .

[18]  Yi-jian Jiang,et al.  The crystal structure of high temperature phase Ta2O5 , 2007 .

[19]  S. Loginova,et al.  Rietveld analysis of X-ray diffraction pattern from β-Ta2O5 oxide , 2002 .

[20]  L. Kleinman,et al.  Theoretical study of structural and electronic properties ofβ−Ta2O5andδ−Ta2O5 , 2004 .

[21]  L. Ley,et al.  The one phonon Raman spectrum in microcrystalline silicon , 1981 .

[22]  Yijian Jiang,et al.  Raman scattering study of a phase transition in tantalum pentoxide , 2000 .

[23]  M. Audier,et al.  A very promising piezoelectric property of Ta2O5 thin films. II: Birefringence and piezoelectricity , 2011 .

[24]  A. Bhalla,et al.  Raman investigation on (Ta2O5)1-x(TiO2)x system at different temperatures and pressures , 1997 .

[25]  H. Terui,et al.  Refractive index and attenuation characteristics of SiO2-Ta2O5 optical waveguide film. , 1983, Applied optics.

[26]  Philippe Colomban,et al.  Raman Spectroscopy of Nanomaterials: How Spectra Relate to Disorder, Particle Size and Mechanical Properties , 2007 .

[27]  J. Autran,et al.  Comparison between the properties of amorphous and crystalline Ta2O5 thin films deposited on Si , 1999 .