Local Optical Probes of Microwave Dielectric Dispersion in Ferroelectric Thin Films

1999 ◽  
Vol 603 ◽  
Author(s):  
Charles Hubert ◽  
Jeremy Levy ◽  
E. J. Cukauskas ◽  
Steven W. Kirchoefer ◽  
Jeffrey M. Pond ◽  
...  
Keyword(s):  
Thin Films ◽  
Soft Mode ◽  
Dielectric Dispersion ◽  
Ferroelectric Thin Films ◽  
Optical Measurements ◽  
Polar Regions ◽  
Time Resolved ◽  
Microwave Dielectric ◽  
Confocal Scanning ◽  
Scanning Optical Microscopy

AbstractThe soft-mode contribution to the dielectric response of Ba0.5Sr0.5TiO3 ferroelectric thin films is measured locally at microwave frequencies using time-resolved confocal scanning optical microscopy. Optical measurements performed on an ensemble of nanometer-scale regions show a well-defined phase shift between the paraelectric and ferroelectric response at 2-4 GHz. Application of a static electric field produces large local variations in the phase of the ferroelectric response. These variations are attributed to the growth of a-axis ferroelectric nanodomains whose size-dependent relaxation frequencies lead to strong dielectric dispersion at mesoscopic scales. The in-plane paraelectric response is believed to arise from the surrounding c-axis matrix and non-polar regions, and shows negligible dispersion. These results provide a direct view of the soft-mode mechanisms of microwave dielectric loss in ferroelectric thin films.

Confocal scanning optical microscopy of BaxSr1−xTiO3 thin films

1997 ◽  
Vol 71 (23) ◽  
pp. 3353-3355 ◽  
Author(s):  
Charles Hubert ◽  
Jeremy Levy ◽  
Adrian C. Carter ◽  
Wontae Chang ◽  
Steven W. Kiechoefer ◽  
...  
Keyword(s):  
Thin Films ◽  
Optical Microscopy ◽  
Confocal Scanning ◽  
Scanning Optical Microscopy

Effect of crystallinity on the dielectric loss of sputter-deposited (Ba,Sr)TiO3 thin films in the microwave range

2003 ◽  
Vol 18 (3) ◽  
pp. 682-686 ◽  
Author(s):  
Tae-Gon Kim ◽  
Jeongmin Oh ◽  
Taeho Moon ◽  
Yongjo Kim ◽  
Byungwoo Park ◽  
...  
Keyword(s):  
Thin Films ◽  
Equivalent Circuit Model ◽  
Sputter Deposition ◽  
Dielectric Losses ◽  
Polar Regions ◽  
Microwave Range ◽  
Si Substrate ◽  
Microwave Dielectric ◽  
Sputter Deposited ◽  
Tan Δ

The crystallinity dependence of the microwave dielectric losses in (Ba,Sr)TiO3 thin films was investigated. The sputter-deposition temperatures were altered to vary the level of thin-film crystallinity on a Pt/Si substrate. The dielectric losses (tan δ) were measured up to 6 GHz without parasitic (stray) effects by using a circular-patch capacitor geometry and an equivalent-circuit model. The microwave dielectric losses increased from 0.0024 ± 0.0018 to 0.0102 ± 0.0017 with increasing crystallinity. These deteriorated dielectric losses showed a good correlation with the symmetry-breaking defects, as confirmed by Raman spectra at approximately 760 cm−1, inducing microscopic polar regions above the Curie temperature of the bulk (Ba0.43Sr0.57)TiO3.

High-resolution scanning optical microscopy of ferroelectric thin films

1999 ◽  
Vol 222 (1) ◽  
pp. 181-188
Author(s):  
Jeremy Levy ◽  
Charles Hubert ◽  
Adrian C. Carter ◽  
Wontae Chang ◽  
Steven W. Kirchoefer ◽  
...  
Keyword(s):  
Thin Films ◽  
High Resolution ◽  
Optical Microscopy ◽  
Ferroelectric Thin Films ◽  
Scanning Optical Microscopy

High-Resolution Optical Microscopy Of BaXSr1−xTio3 Films

1997 ◽  
Vol 493 ◽  
Author(s):  
C. Hubert ◽  
J. Levy ◽  
A. C. Carter ◽  
W. Chang ◽  
J. M. Pond ◽  
...  
Keyword(s):  
Thin Films ◽  
Electric Field ◽  
Optical Microscopy ◽  
Hysteresis Loops ◽  
Laser Deposition ◽  
Ac Electric Field ◽  
Ferroelectric Domain Structure ◽  
Dc Electric Field ◽  
Confocal Scanning ◽  
Scanning Optical Microscopy

ABSTRACTThe ferroelectric polarization of thin films of BaxSr1−xTiO3 is imaged using confocal scanning optical microscopy (CSOM). The thin films are grown by pulsed laser deposition (PLD) on SrTiO3 substrates. Ferroelectric domain structure is imaged by applying a small ac electric field across interdigitated electrodes, and measuring induced reflectivity changes in the film, which are directly related to the polarization. Domain re-orientation is observed by acquiring CSOM images as a function of the dc electric field. Local hysteresis loops are obtained by sweeping the dc electric field at fixed positions on the sample. Micrometer-sized regions exhibit both ferroelectric and paraelectric response, indicating that thermal broadening of the phase transition is largely due to inhomogeneities in the thin films.

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