Raman scattering study of a phase transition in tantalum pentoxide

Ta2O5 ceramics and crystals were prepared and analyzed using Raman spectroscopy in the temperature range 25–873 K. The low-energy phonon bands (ν < 100 cm−1) of Ta2O5 are assigned to external modes originating from the interaction between different Ta polyhedra and TaOn5 − 2n Ta6O126+ clusters. The temperature and polarization dependence of external modes suggests the existence of clusters in the material. A softening of the low-energy bands was observed with increasing temperature. The spectral evolutions show a soft mode-derived second-order monoclinic to orthorhombic phase transition at about 600 K in Ta2O5. Copyright © 2000 John Wiley & Sons, Ltd.

[1]  G. M. Rao,et al.  Rapid thermal processed thin films of reactively sputtered Ta2O5 , 1995 .

[2]  E. J. Rymaszewski,et al.  Electrical characteristics of thin Ta2O5 films deposited by reactive pulsed direct-current magnetron sputtering , 2000 .

[3]  Amar S. Bhalla,et al.  Growth of SrxBa1−xNb2O6 single crystal fibers , 1989 .

[4]  R. Nuzzo,et al.  Monolayer‐Mediated Deposition of Tantalum(V) Oxide Thin Film Structures from Solution Precursors , 1997 .

[5]  J. Scott.  Evidence of Coupling Between One- and Two-Phonon Excitations in Quartz , 1968 .

[6]  Z. Fu,et al.  Processing and Characterization of Ta2O5 Films Deposited by Pulsed Laser Ablation , 1999 .

[7]  A. Rae.  The structural phase change in s-triazine: the quasiharmonic approximation , 1982 .

[8]  Jong-Wan Park,et al.  Effect of rapid thermal annealing treatment on electrical properties and microstructure of tantalum oxide thin film deposited by plasma‐enhanced chemical vapor deposition , 1995 .

[9]  Gunnar A. Niklasson,et al.  A frequency response and transient current study of β-Ta2O5: Methods of estimating the dielectric constant, direct current conductivity, and ion mobility , 1999 .

[10]  H. Viljoen,et al.  A study of piezoelectric orthorhombic Ta 2 O 5 , 1998 .

[11]  H. Bakker.  The relation between the isotope effect for diffusion and the correlation factor in systems lacking a two-fold symmetry around the tracer jump vector , 1971 .

[12]  S. Ezhilvalavan,et al.  Preparation and properties of tantalum pentoxide (Ta2O5) thin films for ultra large scale integrated circuits (ULSIs) application – A review , 1999 .

[13]  J. Scott.  Soft-mode spectroscopy: Experimental studies of structural phase transitions , 1974 .

[14]  M. Yamada,et al.  Ta2O5 thin films with exceptionally high dielectric constant , 1999 .

[15]  M. Cevro,et al.  Ion-beam sputtering of (Ta2O5)x− (SiO2)1−x composite thin films , 1995 .

[16]  Z. Iqbal,et al.  The Raman spectrum and phase transition in sym‐triazine , 1975 .

[17]  In situ infrared spectroscopic analysis of the adsorption of aromatic carboxylic acids to TiO2, ZrO2, Al2O3, and Ta2O5 from aqueous solutions. , 1999 .

[18]  R. Guo,et al.  Ba(Mg1/3Ta2/3)O3 single crystal fiber grown by the laser heated pedestal growth technique , 1994 .

[19]  W. Cochran.  Crystal Stability and the Theory of Ferroelectricity , 1959 .

[20]  Yuhong Huang,et al.  Far-infrared dielectric response of PbTiO3 and PbZr1-xTixO3 thin ferroelectric films , 1995 .

[21]  Robert Joseph Cava,et al.  Dielectric properties of Ta2O5–ZrO2 polycrystalline ceramics , 1996 .

[22]  R. Roth,et al.  Effect of Oxide Additions on the Polymorphism of Tantalum Pentoxide: III. "Stabilization" of the Low Temperature Structure Type. , 1970, Journal of research of the National Bureau of Standards. Section A, Physics and chemistry.

[23]  D. O'shea,et al.  Raman Scattering Study of the Alpha-Beta Phase Transition in Quartz , 1967 .

[24]  Room-temperature radio frequency sputtered Ta2O5: A new etch mask for bulk silicon dissolved processes , 1999 .

[25]  Q. Qin,et al.  Matrix-isolation infrared spectroscopic studies on ablated products generated from laser ablation of Ta2O5 and Ta in ambient O2/Ar gas , 1999 .

[26]  S. W. Park,et al.  Effects of annealing conditions on the properties of tantalum oxide films on silicon substrates , 1992 .

[27]  Y. Tzeng,et al.  High-performance tantalum oxide capacitors fabricated by a novel reoxidation scheme , 1990 .