Pub Date : 2006-07-01DOI: 10.1109/ISAF.2006.4387823
E. Gorzkowski, M. Pan, B. Bender, C. Wu
Barium strontium titanate has been targeted as one potential ferroelectric glass-ceramic for high energy density dielectric materials. Previous testing has shown that the dielectric constant of these materials was as high as 1000 and dielectric breakdown strength up to 800 kV/cm. This did not, however, result in exceptional energy density (~ 0.90 J/cm3). In order to increase overall energy density refining agents can be added to the melt, but the nucleation and growth of the ceramic particles can also play a role. Therefore, in this study the crystallization kinetics were observed to more fully understand how the barium strontium titanate (BST) phase forms so that the optimal energy density could be achieved. It was found that the activation energy was 400 -430 kJ/mol, while the average Avrami parameter was 2.2 -2.5 for BST 70/30 with various additives. The activation energy is close to the disassociation of the Si-O bonds, while crystallization most likely occurs in the bulk with the mechanism of growth being interface controlled.
{"title":"Crystallization Kinetics of Barium Strontium Titanate Glass-Ceramics","authors":"E. Gorzkowski, M. Pan, B. Bender, C. Wu","doi":"10.1109/ISAF.2006.4387823","DOIUrl":"https://doi.org/10.1109/ISAF.2006.4387823","url":null,"abstract":"Barium strontium titanate has been targeted as one potential ferroelectric glass-ceramic for high energy density dielectric materials. Previous testing has shown that the dielectric constant of these materials was as high as 1000 and dielectric breakdown strength up to 800 kV/cm. This did not, however, result in exceptional energy density (~ 0.90 J/cm3). In order to increase overall energy density refining agents can be added to the melt, but the nucleation and growth of the ceramic particles can also play a role. Therefore, in this study the crystallization kinetics were observed to more fully understand how the barium strontium titanate (BST) phase forms so that the optimal energy density could be achieved. It was found that the activation energy was 400 -430 kJ/mol, while the average Avrami parameter was 2.2 -2.5 for BST 70/30 with various additives. The activation energy is close to the disassociation of the Si-O bonds, while crystallization most likely occurs in the bulk with the mechanism of growth being interface controlled.","PeriodicalId":441219,"journal":{"name":"2006 15th ieee international symposium on the applications of ferroelectrics","volume":"40 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128772205","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2006-07-01DOI: 10.1109/ISAF.2006.4387882
M. Guennou, C. Augier, H. Dammak, M. Thi, P. Gaucher
We studied the influence of Mn doping on electromechanical properties of PZN-xPT with x = 7% and 9%. Single crystals oriented along the [111], [011] and [001] directions were poled by a "field cooling" process with an applied electric field of 1 kV/cm. It is shown that Mn doping has a significant influence on the single domain crystals in both cases. It modifies the phase symmetry of single domain PZN-7PT from orthorhombic to rhombohedral. It reduces permittivity perpendicular to polarization direction of single domain PZN-9PT by about 40%. This change in the properties of the bulk material is the main cause for the decrease of permittivity observed in [001] poled PZN-9PT crystals. Further effects of doping on the properties of [001] domain engineered crystals are a decrease of the piezoelectric coefficient, a hardening of the material and an increase of the mechanical quality factor.
{"title":"Role of Mn Doping on the Electromechanical Properties of [001] Domain Engineered Single crystals","authors":"M. Guennou, C. Augier, H. Dammak, M. Thi, P. Gaucher","doi":"10.1109/ISAF.2006.4387882","DOIUrl":"https://doi.org/10.1109/ISAF.2006.4387882","url":null,"abstract":"We studied the influence of Mn doping on electromechanical properties of PZN-xPT with x = 7% and 9%. Single crystals oriented along the [111], [011] and [001] directions were poled by a \"field cooling\" process with an applied electric field of 1 kV/cm. It is shown that Mn doping has a significant influence on the single domain crystals in both cases. It modifies the phase symmetry of single domain PZN-7PT from orthorhombic to rhombohedral. It reduces permittivity perpendicular to polarization direction of single domain PZN-9PT by about 40%. This change in the properties of the bulk material is the main cause for the decrease of permittivity observed in [001] poled PZN-9PT crystals. Further effects of doping on the properties of [001] domain engineered crystals are a decrease of the piezoelectric coefficient, a hardening of the material and an increase of the mechanical quality factor.","PeriodicalId":441219,"journal":{"name":"2006 15th ieee international symposium on the applications of ferroelectrics","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129288070","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2006-07-01DOI: 10.1109/ISAF.2006.4387846
M. B. Assouar, B. Vincent, H. Moubchir, O. Elmazria, A. Khelif, V. Laude
We report here, the study of domain inversion in lithium niobate (z-cut) by electron beam irradiation without any static bias associated to wet etching, in view of the fabrication of phononic crystals. The inverted domains are revealed by HF-etching taking advantage of the large difference in etching rate between z+ and z-faces. A pertinent choice of irradiation conditions such as accelerating voltage, probe current and injected dose, (parameters of interest for the geometry and size of the obtained domains), was determined and optimized. Two dimensional structures at the micrometer scale were then realized on z-cut LiNbO3. We demonstrate the achievement of 8 mum diameter hexagons, with a very large depth close to 30 mum, which depends on the etching time. The obtained structures were characterized before etching by optical microscopy to visualize the inverted domains, and after etching by field emission scanning electron microscopy. These characterisations pointed out the high occupancy rate of obtained structures. Numerical simulations of the realized phononic structure band gap show a frequency band gap around 200 MHz.
{"title":"Domains Inversion in LiNbO3 Using Electron Beam Irradiation for Phononic Crystals","authors":"M. B. Assouar, B. Vincent, H. Moubchir, O. Elmazria, A. Khelif, V. Laude","doi":"10.1109/ISAF.2006.4387846","DOIUrl":"https://doi.org/10.1109/ISAF.2006.4387846","url":null,"abstract":"We report here, the study of domain inversion in lithium niobate (z-cut) by electron beam irradiation without any static bias associated to wet etching, in view of the fabrication of phononic crystals. The inverted domains are revealed by HF-etching taking advantage of the large difference in etching rate between z+ and z-faces. A pertinent choice of irradiation conditions such as accelerating voltage, probe current and injected dose, (parameters of interest for the geometry and size of the obtained domains), was determined and optimized. Two dimensional structures at the micrometer scale were then realized on z-cut LiNbO3. We demonstrate the achievement of 8 mum diameter hexagons, with a very large depth close to 30 mum, which depends on the etching time. The obtained structures were characterized before etching by optical microscopy to visualize the inverted domains, and after etching by field emission scanning electron microscopy. These characterisations pointed out the high occupancy rate of obtained structures. Numerical simulations of the realized phononic structure band gap show a frequency band gap around 200 MHz.","PeriodicalId":441219,"journal":{"name":"2006 15th ieee international symposium on the applications of ferroelectrics","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127854638","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2006-07-01DOI: 10.1109/ISAF.2006.4387824
M. Pan, E. Gorzkowski, B. Bender, C. Wu
In the last two years, the US Naval Research Laboratory has been able to synthesize barium strontium titanate (BST)-based glass-ceramics with dielectric breakdown strength as high as 800 kV/cm and dielectric constant up to 1200. Unfortunately, the energy density of the candidate glass-ceramics was only ~1 joule/cc when measured using a discharge measurement circuit. Polarization-electric field measurements revealed wide open hysteresis loops, indicating that most of the electrical energy was not released during discharge. Subsequent experiments showed that the buildup of interfacial polarization was the likely cause in this composite dielectric system. Using the Maxwell-Wagner capacitor model, we were able to quantify the dielectric response of composites based on the permittivities and conductivities of the constituent phases. The response was used to plot polarization-electric field hysteresis for energy density predictions. The results indicated that the aluminosilicate glass phase is the major contributor to the interfacial polarization in this glass-ceramic system.
{"title":"The Effect of Interfacial Polarization on the Energy Density of Ferroelectric Glass-Ceramics","authors":"M. Pan, E. Gorzkowski, B. Bender, C. Wu","doi":"10.1109/ISAF.2006.4387824","DOIUrl":"https://doi.org/10.1109/ISAF.2006.4387824","url":null,"abstract":"In the last two years, the US Naval Research Laboratory has been able to synthesize barium strontium titanate (BST)-based glass-ceramics with dielectric breakdown strength as high as 800 kV/cm and dielectric constant up to 1200. Unfortunately, the energy density of the candidate glass-ceramics was only ~1 joule/cc when measured using a discharge measurement circuit. Polarization-electric field measurements revealed wide open hysteresis loops, indicating that most of the electrical energy was not released during discharge. Subsequent experiments showed that the buildup of interfacial polarization was the likely cause in this composite dielectric system. Using the Maxwell-Wagner capacitor model, we were able to quantify the dielectric response of composites based on the permittivities and conductivities of the constituent phases. The response was used to plot polarization-electric field hysteresis for energy density predictions. The results indicated that the aluminosilicate glass phase is the major contributor to the interfacial polarization in this glass-ceramic system.","PeriodicalId":441219,"journal":{"name":"2006 15th ieee international symposium on the applications of ferroelectrics","volume":"87 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121240220","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2006-07-01DOI: 10.1109/ISAF.2006.4387821
M. Klee, D. Beelen, W. Keur, R. Kiewitt, B. Kumar, R. Mauczok, K. Reimann, C. Renders, A. Roest, F. Roozeboom, P. Steeneken, M. Tiggelman, F. Vanhelmont, O. Wunnicke, P. Lok, K. Neumann, J. Fraser, G. Schmitz
Dielectric, ferroelectric and piezoelectric thin films are getting more and more attention for next generation mobile communication and medical systems. Thin film technologies based on dielectric, ferroelectric and piezoelectric thin films enable system-in-package (SiP) devices, resulting in optimal integration of various functions in one module with respect to high performance, small size and low cost. Within Philips a passive integration platform for SiP technologies is developed, comprising key functions such as RF filters, micro-electromechanical switches, high-value capacitors as well as passive and active functions integrated in small modules. The piezoelectric thin film technologies do not only play a role for RF filters, but are also a breakthrough technology for a new class of thin film ultrasonic transducers.
{"title":"Application of Dielectric, Ferroelectric and Piezoelectric Thin Film Devices in Mobile Communication and Medical Systems","authors":"M. Klee, D. Beelen, W. Keur, R. Kiewitt, B. Kumar, R. Mauczok, K. Reimann, C. Renders, A. Roest, F. Roozeboom, P. Steeneken, M. Tiggelman, F. Vanhelmont, O. Wunnicke, P. Lok, K. Neumann, J. Fraser, G. Schmitz","doi":"10.1109/ISAF.2006.4387821","DOIUrl":"https://doi.org/10.1109/ISAF.2006.4387821","url":null,"abstract":"Dielectric, ferroelectric and piezoelectric thin films are getting more and more attention for next generation mobile communication and medical systems. Thin film technologies based on dielectric, ferroelectric and piezoelectric thin films enable system-in-package (SiP) devices, resulting in optimal integration of various functions in one module with respect to high performance, small size and low cost. Within Philips a passive integration platform for SiP technologies is developed, comprising key functions such as RF filters, micro-electromechanical switches, high-value capacitors as well as passive and active functions integrated in small modules. The piezoelectric thin film technologies do not only play a role for RF filters, but are also a breakthrough technology for a new class of thin film ultrasonic transducers.","PeriodicalId":441219,"journal":{"name":"2006 15th ieee international symposium on the applications of ferroelectrics","volume":"301 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114480275","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2006-07-01DOI: 10.1109/ISAF.2006.4387827
R. Yimnirun, S. Wongsaenmai, Y. Laosiritaworn, S. Ananta
The ferroelectric properties under uniaxial compressive pre-stress and scaling behavior of commercial soft PZT ceramics are investigated. The ferroelectric properties under the uniaxial compressive pre-stress of the ceramics are observed at stress up to 24 MPa using a compressometer in conjunction with a modified Sawyer-Tower circuit. The results show that the ferroelectric characteristics, i.e. the area of the ferroelectric hysteresis (P-E) loops, the saturation polarization (Psat), the remanent polarization (Pr), and the loop squareness (Rsq) decrease with increasing compressive pre-stress, while the coercive field (Ec) is virtually unaffected by the applied stress. The stress-induced domain wall motion suppression and non-180deg ferroelectic domain switching processes are responsible for the changes observed. In addition, a significant decrease in those parameters after a full cycle of stress application has been observed and attributed to the stress induced decrease in switchable part of spontaneous polarization at high stress. Finally, the dynamic behavior of the ferroelectric properties is also examined to establish the scaling behavior of the soft PZT ceramics. It has been found that the scaling behavior found for the bulk ceramic differs slightly from the theoretical prediction and that obtained from the experimental investigation on thin-film.
{"title":"Uniaxial Stress Dependence and Scaling Behavior of Dynamic Hysteresis Responses in Soft PZT Ceramics","authors":"R. Yimnirun, S. Wongsaenmai, Y. Laosiritaworn, S. Ananta","doi":"10.1109/ISAF.2006.4387827","DOIUrl":"https://doi.org/10.1109/ISAF.2006.4387827","url":null,"abstract":"The ferroelectric properties under uniaxial compressive pre-stress and scaling behavior of commercial soft PZT ceramics are investigated. The ferroelectric properties under the uniaxial compressive pre-stress of the ceramics are observed at stress up to 24 MPa using a compressometer in conjunction with a modified Sawyer-Tower circuit. The results show that the ferroelectric characteristics, i.e. the area of the ferroelectric hysteresis (P-E) loops, the saturation polarization (Psat), the remanent polarization (Pr), and the loop squareness (Rsq) decrease with increasing compressive pre-stress, while the coercive field (Ec) is virtually unaffected by the applied stress. The stress-induced domain wall motion suppression and non-180deg ferroelectic domain switching processes are responsible for the changes observed. In addition, a significant decrease in those parameters after a full cycle of stress application has been observed and attributed to the stress induced decrease in switchable part of spontaneous polarization at high stress. Finally, the dynamic behavior of the ferroelectric properties is also examined to establish the scaling behavior of the soft PZT ceramics. It has been found that the scaling behavior found for the bulk ceramic differs slightly from the theoretical prediction and that obtained from the experimental investigation on thin-film.","PeriodicalId":441219,"journal":{"name":"2006 15th ieee international symposium on the applications of ferroelectrics","volume":"89 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126221837","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2006-07-01DOI: 10.1109/ISAF.2006.4387909
M. Schmidt, E. Lourandakis, R. Weigel, A. Leidl, S. Seitz
A simple model of thin film BST varactors for the use in commercial circuit simulators is presented. The model implies the varactor's nonlinear capacitance as well as the frequency and voltage dependency of the losses. For the use of BST based components in mobile communication systems low tuning voltages are required. This leads unfortunately to high nonlinear distortion which is not acceptable. Another severe problem are the moderate to low quality factors and therefore high losses of the ferroelectric capacitors. The presented model allows estimating the losses and the distortion over a wide frequency range at every bias state with harmonic balance and envelope simulations. Further more it is now possible to predict the behavior of a designed circuit but also to deduce the requirements for BST varactors in order to achieve the demanded design goals. The model consists of a parallel circuit of equation based elements which represents the nonlinear capacitance and conductance. A constant series inductance and a constant resistance model the contacts. The required parameters can easily be extracted through measurements. To demonstrate the validity of the presented model a BST based SP2T switch at 1800 MHz was designed. An insertion loss of 1.4 dB at an isolation of 21 dB and a TOI of 35 dBm were achieved. The simulation and measurement results agree very good over a wide frequency range.
{"title":"A Thin-Film BST Varactor Model for Linear and Nonlinear Circuit Simulations for Mobile Communication Systems","authors":"M. Schmidt, E. Lourandakis, R. Weigel, A. Leidl, S. Seitz","doi":"10.1109/ISAF.2006.4387909","DOIUrl":"https://doi.org/10.1109/ISAF.2006.4387909","url":null,"abstract":"A simple model of thin film BST varactors for the use in commercial circuit simulators is presented. The model implies the varactor's nonlinear capacitance as well as the frequency and voltage dependency of the losses. For the use of BST based components in mobile communication systems low tuning voltages are required. This leads unfortunately to high nonlinear distortion which is not acceptable. Another severe problem are the moderate to low quality factors and therefore high losses of the ferroelectric capacitors. The presented model allows estimating the losses and the distortion over a wide frequency range at every bias state with harmonic balance and envelope simulations. Further more it is now possible to predict the behavior of a designed circuit but also to deduce the requirements for BST varactors in order to achieve the demanded design goals. The model consists of a parallel circuit of equation based elements which represents the nonlinear capacitance and conductance. A constant series inductance and a constant resistance model the contacts. The required parameters can easily be extracted through measurements. To demonstrate the validity of the presented model a BST based SP2T switch at 1800 MHz was designed. An insertion loss of 1.4 dB at an isolation of 21 dB and a TOI of 35 dBm were achieved. The simulation and measurement results agree very good over a wide frequency range.","PeriodicalId":441219,"journal":{"name":"2006 15th ieee international symposium on the applications of ferroelectrics","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129588022","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2006-07-01DOI: 10.1109/ISAF.2006.4387891
Hong Liu, Xiaogang Gong, Jin-e Liang, Zhihong Wang, Hui-Ching Huang, Yanrong Li, D. Xiao, Jianguo Zhu
The Pb0.9La0.1Ti0.975O3 (PLT10) thin films were grown on Pt/Ti/SiO2/Si(100) substrates by using RF magnetron sputtering. The crystalline and domain properties of PLT 10 thin films were studied by using X-ray diffraction (XRD) and piezoresponse force microscopy (PFM). It was found that the head-to-tail polarization configurations exist constantly in PLT thin films, indicating that the low electrical energy configurations are quite common in PLT thin films. Nanoscale banded 90deg a-a domain patterns as small as 30 to 60 nm in width were clearly visualized in the PLT thin films. The banded domain alternated in adjacent lamellae which are a result of mechanical strains at the surface and the interface between the substrate and the PLT thin films is more stable. The PLT films have relatively large pyroelectric coefficient gamma=2.20times10-8 Cldr(cm2ldrK)-1 and relatively high figures of merit. Hence PLT10 thin films could be applied widely in IR detectors or uncooled focus plane arrays.
{"title":"The Domain Structure and Pyroelectric Properties of (111) Preferred Oriented PLT Thin Films Prepared By RF Magnetron Sputtering","authors":"Hong Liu, Xiaogang Gong, Jin-e Liang, Zhihong Wang, Hui-Ching Huang, Yanrong Li, D. Xiao, Jianguo Zhu","doi":"10.1109/ISAF.2006.4387891","DOIUrl":"https://doi.org/10.1109/ISAF.2006.4387891","url":null,"abstract":"The Pb0.9La0.1Ti0.975O3 (PLT10) thin films were grown on Pt/Ti/SiO2/Si(100) substrates by using RF magnetron sputtering. The crystalline and domain properties of PLT 10 thin films were studied by using X-ray diffraction (XRD) and piezoresponse force microscopy (PFM). It was found that the head-to-tail polarization configurations exist constantly in PLT thin films, indicating that the low electrical energy configurations are quite common in PLT thin films. Nanoscale banded 90deg a-a domain patterns as small as 30 to 60 nm in width were clearly visualized in the PLT thin films. The banded domain alternated in adjacent lamellae which are a result of mechanical strains at the surface and the interface between the substrate and the PLT thin films is more stable. The PLT films have relatively large pyroelectric coefficient gamma=2.20times10-8 Cldr(cm2ldrK)-1 and relatively high figures of merit. Hence PLT10 thin films could be applied widely in IR detectors or uncooled focus plane arrays.","PeriodicalId":441219,"journal":{"name":"2006 15th ieee international symposium on the applications of ferroelectrics","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132234199","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2006-07-01DOI: 10.1109/ISAF.2006.4387836
W. Simon, E. K. Akdoğan, A. Safari
Strain relaxation in (Ba0.60 Sr0.40)TiO3 epitaxial films on <110>-oriented NdGaO3 substrates is investigated in the thickness range, h= 25-1200 nm. The BST films prepared by PLD show that residual strains mostly relax by h~200 nm, and for h>600 nm films are essentially strain free. Two independent dislocation mechanisms operate to relax anisotropic strains along the principal directions. The critical thickness for misfit dislocation formation along [001] and [010] were found to be 11 and 15 nm, respectively. Deviation from linear elasticity for h<200 was observed, and increased as thickness decreased. Films with h<25 nm are monoclinic due to a finite principal shear stress along [110] of the BST cell. The effects of misfit strain relaxation on the nonlinear dielectric response and tunability will be discussed as well. The in plane dielectric response demonstrates a directional dependence that increases with the magnitude of the residual strain.
{"title":"Effect of Misfit Strain Relaxation on Nonlinear Dielectric Properties of Epitaxial (Ba0.60 Sr0.40) Thin Films on NdGaO3","authors":"W. Simon, E. K. Akdoğan, A. Safari","doi":"10.1109/ISAF.2006.4387836","DOIUrl":"https://doi.org/10.1109/ISAF.2006.4387836","url":null,"abstract":"Strain relaxation in (Ba0.60 Sr0.40)TiO3 epitaxial films on <110>-oriented NdGaO3 substrates is investigated in the thickness range, h= 25-1200 nm. The BST films prepared by PLD show that residual strains mostly relax by h~200 nm, and for h>600 nm films are essentially strain free. Two independent dislocation mechanisms operate to relax anisotropic strains along the principal directions. The critical thickness for misfit dislocation formation along [001] and [010] were found to be 11 and 15 nm, respectively. Deviation from linear elasticity for h<200 was observed, and increased as thickness decreased. Films with h<25 nm are monoclinic due to a finite principal shear stress along [110] of the BST cell. The effects of misfit strain relaxation on the nonlinear dielectric response and tunability will be discussed as well. The in plane dielectric response demonstrates a directional dependence that increases with the magnitude of the residual strain.","PeriodicalId":441219,"journal":{"name":"2006 15th ieee international symposium on the applications of ferroelectrics","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131330797","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2006-07-01DOI: 10.1109/ISAF.2006.4387895
R. Mamazza, N. Mark, R. Polcawich, B. Piekarski, P. Muralt, G. Reynolds
A new process for the sputter deposition of Pb(Zr,Ti)O3 (PZT) thin films from a composite target has been demonstrated. PZT thin films deposited by this sputter technique are compared to those deposited by a standard sol-gel method to determine the suitability of the sputter deposition process, with its inherent advantages, for device manufacturing. Half micron PZT films were deposited by both methods onto identical substrates (Si[(100) 4 inch Cz wafer]/SiO2/Ti/TiO2/Pt/TiO2) followed by sputter-deposited Pt top electrodes. PZT thickness non-uniformities of 0.759% and 0.545% (1sigma/x macr) were obtained for the sol-gel and sputtered films, respectively. While the sputtering target and sol-gel solutions were Zr-rich (Zr/Ti=1.08), RBS results revealed the films to be Ti-rich: for sol-gel, Zr/Ti=0.874, and for sputtered, Zr/Ti=0.926. X-ray diffraction indicated preferred orientations nearly exclusive to the [111] direction for the sputtered films. For the sol-gel PZT, the larger [110] and [100] peaks indicated a more randomly textured film. SEM cross-sections showed both types of PZT to be void-free and homogeneous. The remnant polarization (Pr) and coercive field (Ec) values of the sol-gel films were slightly higher than for their sputtered analogue: for sol-gel, Pr = 27.9 muCldrcm-2 and Ec = 70.7 kVldrcm-1, and for sputtered, Pr = 26.5 muCldrcm-2 and Ec = 63.3 kVldrcm-1. The sputtered films exhibited a higher dielectric constant, epsiv33sputtered = 858 compared to epsiv33sol-gel = 776. Piezoelectric coefficients, d33, for the sputtered films were found to be 86 pCldrN-1, in the range of those measured for typical sol-gel films (between 70 and 100 pCldrN-1). The advantages and disadvantages of both techniques will be discussed in greater detail.
{"title":"Comparison of Ferroelectric and Piezoelectric Properties of Sol-gel Grown and Sputter Deposited Pb(Zr, Ti)O3 Thin Films","authors":"R. Mamazza, N. Mark, R. Polcawich, B. Piekarski, P. Muralt, G. Reynolds","doi":"10.1109/ISAF.2006.4387895","DOIUrl":"https://doi.org/10.1109/ISAF.2006.4387895","url":null,"abstract":"A new process for the sputter deposition of Pb(Zr,Ti)O<sub>3</sub> (PZT) thin films from a composite target has been demonstrated. PZT thin films deposited by this sputter technique are compared to those deposited by a standard sol-gel method to determine the suitability of the sputter deposition process, with its inherent advantages, for device manufacturing. Half micron PZT films were deposited by both methods onto identical substrates (Si[(100) 4 inch Cz wafer]/SiO<sub>2</sub>/Ti/TiO<sub>2</sub>/Pt/TiO<sub>2</sub>) followed by sputter-deposited Pt top electrodes. PZT thickness non-uniformities of 0.759% and 0.545% (1sigma/x macr) were obtained for the sol-gel and sputtered films, respectively. While the sputtering target and sol-gel solutions were Zr-rich (Zr/Ti=1.08), RBS results revealed the films to be Ti-rich: for sol-gel, Zr/Ti=0.874, and for sputtered, Zr/Ti=0.926. X-ray diffraction indicated preferred orientations nearly exclusive to the [111] direction for the sputtered films. For the sol-gel PZT, the larger [110] and [100] peaks indicated a more randomly textured film. SEM cross-sections showed both types of PZT to be void-free and homogeneous. The remnant polarization (P<sub>r</sub>) and coercive field (E<sub>c</sub>) values of the sol-gel films were slightly higher than for their sputtered analogue: for sol-gel, P<sub>r</sub> = 27.9 muCldrcm<sup>-2</sup> and E<sub>c</sub> = 70.7 kVldrcm<sup>-1</sup>, and for sputtered, P<sub>r</sub> = 26.5 muCldrcm<sup>-2</sup> and E<sub>c</sub> = 63.3 kVldrcm<sup>-1</sup>. The sputtered films exhibited a higher dielectric constant, epsiv<sub>33</sub> <sup>sputtered</sup> = 858 compared to epsiv<sub>33</sub> <sup>sol-gel</sup> = 776. Piezoelectric coefficients, d<sub>33</sub>, for the sputtered films were found to be 86 pCldrN<sup>-1</sup>, in the range of those measured for typical sol-gel films (between 70 and 100 pCldrN<sup>-1</sup>). The advantages and disadvantages of both techniques will be discussed in greater detail.","PeriodicalId":441219,"journal":{"name":"2006 15th ieee international symposium on the applications of ferroelectrics","volume":"638 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131341341","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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