Soft-Mode Phonons in SrTiO3 Thin Films Studied by Far-Infrared Ellipsometry and Raman Scattering

1999 ◽  
Vol 603 ◽  
Author(s):  
A. A. Sirenko ◽  
C. Bernhard ◽  
A. Golnik ◽  
I. A. Akimov ◽  
A. M. Clark ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Raman Scattering ◽  
Soft Mode ◽  
Experimental Studies ◽  
Low Frequency ◽  
Pulsed Laser ◽  
Far Infrared ◽  
Laser Deposition ◽  
Bulk Crystals ◽  
Infrared Ellipsometry

AbstractWe report the experimental studies of the vibrational spectra of SrTiO3 films with the thickness of 1 µm grown by pulsed laser deposition. Fourier-transform infrared ellipsometry between 30 and 700 cm−1 and electric field-induced Raman scattering have been utilized for investigation of the phonon behavior. These results can be used for comparison with the low-frequency measurements of the static dielectric constant. In the films, the soft mode reveals hardening compared to that in bulk crystals. This observation is in agreement with the Lyddane-Sachs-Teller formalism.

Microstructural and Electrical Characterization of Barium Strontium Titanatebased Solid Solution Thin Films Deposited on Ceramic Substrates by Pulsed Laser Deposition

2002 ◽  
Vol 720 ◽  
Author(s):  
Costas G. Fountzoulas ◽  
Daniel M. Potrepka ◽  
Steven C. Tidrow
Keyword(s):  
Thin Films ◽  
Dielectric Constant ◽  
Pulsed Laser Deposition ◽  
Pulsed Laser ◽  
Electrical Characterization ◽  
Field Variable ◽  
Laser Deposition ◽  
X Ray Diffraction ◽  
Ceramic Substrates ◽  
Nominal Thickness

AbstractFerroelectrics are multicomponent materials with a wealth of interesting and useful properties, such as piezoelectricity. The dielectric constant of the BSTO ferroelectrics can be changed by applying an electric field. Variable dielectric constant results in a change in phase velocity in the device allowing it to be tuned in real time for a particular application. The microstructure of the film influences the electronic properties which in turn influences the performance of the film. Ba0.6Sr0.4Ti1-y(A 3+, B5+)yO3 thin films, of nominal thickness of 0.65 μm, were synthesized initially at substrate temperatures of 400°C, and subsequently annealed to 750°C, on LaAlO3 (100) substrates, previously coated with LaSrCoO conductive buffer layer, using the pulsed laser deposition technique. The microstructural and physical characteristics of the postannealed thin films have been studied using x-ray diffraction, scanning electron microscopy, and nano indentation and are reported. Results of capacitance measurements are used to obtain dielectric constant and tunability in the paraelectric (T>Tc) regime.

Disorder-Induced Low-Frequency Raman Band Observed in Deposited MoS2 Films

1994 ◽  
Vol 48 (6) ◽  
pp. 733-736 ◽  
Author(s):  
N. T. McDevitt ◽  
J. S. Zabinski ◽  
M. S. Donley ◽  
J. E. Bultman
Keyword(s):  
Crystal Structure ◽  
Thin Films ◽  
Raman Band ◽  
Low Frequency ◽  
Pulsed Laser ◽  
Laser Deposition ◽  
First Order ◽  
Order Spectrum ◽  
History Of ◽  
Frequency Feature

Crystalline disorder in thin films plays an important role in determining their properties. Disorder in the crystal structure of MoS2 films prepared by magnetron sputtering and pulsed laser deposition was evaluated with the use of Raman spectroscopy. The peak positions and bandwidths of the first-order Raman bands, in the region 100 to 500 cm−1, were used as a measure of crystalline order. In addition, a low-frequency feature was observed at 223 cm−1 that is not part of the normal first-order spectrum of a fully crystalline specimen. Data presented here demonstrate that this band is characteristic of crystalline disorder, and its intensity depends on the annealing history of the film. This behavior seems to be analogous to the disorder found in graphite thin films.

Isotope effect on the optical phonons ofYBa2Cu4O8studied by far-infrared ellipsometry and Raman scattering

2006 ◽  
Vol 74 (10) ◽  
Author(s):  
A. Trajnerowicz ◽  
A. Golnik ◽  
C. Bernhard ◽  
L. Machtoub ◽  
C. Ulrich ◽  
...  
Keyword(s):  
Raman Scattering ◽  
Isotope Effect ◽  
Far Infrared ◽  
Optical Phonons ◽  
Infrared Ellipsometry

Pulsed Laser Deposition of BaxSr1−xTiO3 Films on MgO, LaAlO3 and SrTiO3 for Tunable Microwave Applications

1998 ◽  
Vol 541 ◽  
Author(s):  
Wontae Chang ◽  
James S. Horwitz ◽  
Won-Jeong Kim ◽  
Jeffrey M. Pond ◽  
Steven W. Kirchoefer ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Electric Field ◽  
Pulsed Laser Deposition ◽  
Pulsed Laser ◽  
Dielectric Constants ◽  
Laser Deposition ◽  
Film Stress ◽  
Donor Acceptor ◽  
Bst Films

AbstractSingle phase BaxSr1−xTiO3 (BST) films (∼0.5-7 μm thick) have been deposited onto single crystal substrates (MgO, LaAlO3, SrTiO3) by pulsed laser deposition. Silver interdigitated electrodes were deposited on top of the ferroelectric film. The room temperature capacitance and dielectric Q (1/tanδ) of the film have been measured as a function of electric field (≤80 kV/cm) at 1 - 20 GHz. The dielectric properties of the film are observed to strongly depend on substrate type and post-deposition processing. After annealing (≤1000° C), it was observed that the dielectric constant and % tuning decreased and the dielectric Q increased for films deposited onto MgO, and the opposite effect was observed for films deposited onto LaA1O3. Presumably, this change in dielectric properties is due to the changes in film stress. Very thin (∼50 Å) amorphous BST films were successfully used as a stress-relief layer for the subsequently deposited crystalline BST (∼5000 Å) films to maximize % tuning and dielectric Q. Films have been deposited from stoichiometric targets and targets that have excess Ba and Sr. The additional Ba and Sr has been added to the target to compensate for deficiencies in Ba and Sr observed in the deposited BST (x=0.5) films. Films deposited from compensated targets have higher dielectric constants than films deposited from stoichiometric targets. Donor/acceptor dopants have also been added to the BST target (Mn, W, Fe ≤4 mol.%) to further improve the dielectric properties. The relationship between the dielectric constant, the dielectric Q, the change in dielectric constant with electric field is discussed.

Magnetic and Raman scattering studies of Co-doped ZnO thin films grown by pulsed laser deposition

2013 ◽  
Vol 115 (3) ◽  
pp. 843-849 ◽  
Author(s):  
Arun Aravind ◽  
K. Hasna ◽  
M. K. Jayaraj ◽  
Mukesh Kumar ◽  
Ramesh Chandra
Keyword(s):  
Thin Films ◽  
Raman Scattering ◽  
Pulsed Laser Deposition ◽  
Pulsed Laser ◽  
Laser Deposition ◽  
Zno Thin Films ◽  
Doped Zno ◽  
Co Doped

High dielectric constant in CaCu3Ti4O12 thin film prepared by pulsed laser deposition

2003 ◽  
Vol 445 (1) ◽  
pp. 7-13 ◽  
Author(s):  
Y.L. Zhao ◽  
G.W. Pan ◽  
Q.B. Ren ◽  
Y.G. Cao ◽  
L.X. Feng ◽  
...  
Keyword(s):  
Thin Film ◽  
Dielectric Constant ◽  
Pulsed Laser Deposition ◽  
High Dielectric Constant ◽  
Pulsed Laser ◽  
Laser Deposition ◽  
High Dielectric
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