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1Latest Papers from Table of Contents or Articles in PressD. Reich ; N. Patterson ; D. Campbell ; A. Tandon ; S. Mazieres ; N. Ray ; M. V. Parra ; W. Rojas ; C. Duque ; N. Mesa ; L. F. Garcia ; O. Triana ; S. Blair ; A. Maestre ; J. C. Dib ; C. M. Bravi ; G. Bailliet ; D. Corach ; T. Hunemeier ; M. C. Bortolini ; F. M. Salzano ; M. L. Petzl-Erler ; V. Acuna-Alonzo ; C. Aguilar-Salinas ; S. Canizales-Quinteros ; T. Tusie-Luna ; L. Riba ; M. Rodriguez-Cruz ; M. Lopez-Alarcon ; R. Coral-Vazquez ; T. Canto-Cetina ; I. Silva-Zolezzi ; J. C. Fernandez-Lopez ; A. V. Contreras ; G. Jimenez-Sanchez ; M. J. Gomez-Vazquez ; J. Molina ; A. Carracedo ; A. Salas ; C. Gallo ; G. Poletti ; D. B. Witonsky ; G. Alkorta-Aranburu ; R. I. Sukernik ; L. Osipova ; S. A. Fedorova ; R. Vasquez ; M. Villena ; C. Moreau ; R. Barrantes ; D. Pauls ; L. Excoffier ; G. Bedoya ; F. Rothhammer ; J. M. Dugoujon ; G. Larrouy ; W. Klitz ; D. Labuda ; J. Kidd ; K. Kidd ; A. Di Rienzo ; N. B. Freimer ; A. L. Price ; A. Ruiz-Linares
Nature Publishing Group (NPG)
Published 2012Staff ViewPublication Date: 2012-07-18Publisher: Nature Publishing Group (NPG)Print ISSN: 0028-0836Electronic ISSN: 1476-4687Topics: BiologyChemistry and PharmacologyMedicineNatural Sciences in GeneralPhysicsKeywords: Americas ; Asia ; Cluster Analysis ; Emigration and Immigration/*history/statistics & numerical data ; Gene Flow ; Genetics, Population ; History, Ancient ; Humans ; Indians, North American/*genetics/*history ; Models, Genetic ; *Phylogeny ; Polymorphism, Single Nucleotide/genetics ; SiberiaPublished by: -
2Articles: DFG German National LicensesNagarajan, V. ; Jenkins, I. G. ; Alpay, S. P. ; Li, H. ; Aggarwal, S. ; Salamanca-Riba, L. ; Roytburd, A. L. ; Ramesh, R.
[S.l.] : American Institute of Physics (AIP)
Published 1999Staff ViewISSN: 1089-7550Source: AIP Digital ArchiveTopics: PhysicsNotes: We have studied the effect of misfit strain on the microstructure and properties of ferroelectric lead zirconate titanate thin films. We have changed the misfit strain by varying the film thickness and studied the thickness effect on the domain formation of epitaxial PbZr0.2Ti0.8O3 (PZT) films grown by pulsed laser deposition on (001) LaAlO3 substrates with La0.5Sr0.5CoO3 (LSCO) electrodes. The nominal thickness of the PZT films was varied from 60 to 400 nm with the LSCO electrode thickness kept constant at 50 nm. X-ray diffraction experiments show that the films relax via the formation of a domains, the fraction of which increase with the ferroelectric film thickness. The c-axis lattice constant of PZT films calculated from the 002 reflection decreases with increasing film thickness and approaches the bulk value of ∼0.413 nm in the films thicker than 300 nm. Cross-sectional transmission electron microscopy images reveal that the a-domain fraction and period increase with increasing film thickness. The relaxation of misfit strain in the film is accompanied by systematic changes in the polarization properties, as well as the switching fields, quantified by the coercive field and the activation field. © 1999 American Institute of Physics.Type of Medium: Electronic ResourceURL: -
3Articles: DFG German National LicensesOgale, S. B. ; Li, Y. H. ; Rajeswari, M. ; Riba, L. Salamanca ; Ramesh, R. ; Venkatesan, T.
[S.l.] : American Institute of Physics (AIP)
Published 2000Staff ViewISSN: 1089-7550Source: AIP Digital ArchiveTopics: PhysicsNotes: Epitaxial La0.7Ca0.3MnO3 thin films on the SrTiO3(100) surface have been irradiated with 250 MeV Ag17+ ions at different nominal fluence values in the range of 5×1010–4×1011 ions/cm2, resulting in columnar defects. At low fluences these defects cause changes in material properties that are small and scale linearly with dosage. Above a threshold fluence value ∼3×1011 ions/cm2 dramatic changes are observed, including an order of magnitude increase in the resistivity and 50 K drop in the Curie temperature. Transmission electron microscopy measurements show that the changes are associated with a phase transformation of the undamaged region between the columnar defects. The transformed phase has a diffraction pattern very similar to that seen in charge-ordered La0.5Ca0.5MnO3. We propose that above a critical level of ion damage, strains caused by the presence of the columnar defects induce a charge-ordering phase transition that causes the observed dramatic changes in physical properties. We speculate that a conceptually similar surface-induced charge ordering may be responsible for the "dead layer" observed in very thin strained films, and the dramatic changes in optical properties induced by polishing, and that an impurity-induced charge ordering causes the extreme sensitivity of properties to lattice substitution. © 2000 American Institute of Physics.Type of Medium: Electronic ResourceURL: -
4Articles: DFG German National LicensesDahmani, R. ; Salamanca-Riba, L. ; Nguyen, N. V. ; Chandler-Horowitz, D. ; Jonker, B. T.
[S.l.] : American Institute of Physics (AIP)
Published 1994Staff ViewISSN: 1089-7550Source: AIP Digital ArchiveTopics: PhysicsNotes: Spectroscopic ellipsometry was used to determine the real and imaginary parts of the dielectric function of ZnSe thin films grown on (001) GaAs substrates by molecular-beam epitaxy, for energies between 1.5 and 5.0 eV. A sum of harmonic oscillators is used to fit the dielectric function in order to determine the values of the threshold energies at the critical points. The fundamental energy gap was determined to be at 2.68 eV. The E0+Δ0 and E1 points were found to be equal to 3.126 and 4.75 eV, respectively. Below the fundamental absorption edge, a Sellmeir-type function was used to represent the refractive index. At the critical points, E0 and E0+Δ0, the fitting was improved by using an explicit function combining the contributions of these two points to the dielectric function.Type of Medium: Electronic ResourceURL: -
5Articles: DFG German National LicensesMao, S. N. ; Xi, X. X. ; Li, Qi ; Venkatesan, T. ; Beesabathina, D. Prasad ; Salamanca-Riba, L. ; Wu, X. D.
[S.l.] : American Institute of Physics (AIP)
Published 1994Staff ViewISSN: 1089-7550Source: AIP Digital ArchiveTopics: PhysicsNotes: High quality epitaxial Nd2−xCexCuO4−y (NCCO) thin films were fabricated on various substrates by pulsed-laser deposition using N2O reactive gas. The similarities and dissimilarities of the superconducting and structural properties of NCCO films, on perovskite-type substrates such as LaAlO3, NdGaO3, and SrTiO3 and on a fluorite-type substrate of yttria-stabilized zirconia (YSZ), were investigated systematically as a function of film thickness by transport measurements and structural analysis. A remarkable reduction of Tc was observed when the film was thinner than a critical thickness, which strongly depends on the substrate. The critical thicknesses for which Tc is 80% of Tc max are 1200, 1000, 600, and 450 A(ring) for LaAlO3, NdGaO3, SrTiO3, and YSZ, respectively. YSZ turns out to be the best candidate for the growth of very thin NCCO films among the substrates studied. These results show a strong correlation between the strain and Tc in NCCO thin films and point the way to the fabrication of n-type superconducting electric field devices using ultrathin NCCO films.Type of Medium: Electronic ResourceURL: -
6Articles: DFG German National LicensesHua, S. Z. ; Lashmore, D. S. ; Salamanca-Riba, L. ; Schwarzacher, W. ; Swartzenruber, L. J. ; McMichael, R. D. ; Bennett, L. H. ; Hart, R.
[S.l.] : American Institute of Physics (AIP)
Published 1994Staff ViewISSN: 1089-7550Source: AIP Digital ArchiveTopics: PhysicsNotes: Giant magnetoresistance (GMR) of CoNiCu/Cu multilayers grown by electrodeposition was measured as a function of the copper layer thickness and effects of the order of 14% were obtained. The copper layer thickness ranged from 0.7 to 3.5 nm. Two peaks in the magnetoresistance were observed. One was centered at a copper thickness of ∼1.0 nm and the second was centered at ∼2.3 nm. Comparison of the field dependence of the magnetoresistance with the field dependence of the magnetization, as determined by vibrating-sample magnetometer, suggests that the saturation field for GMR and the magnetization are similar for the larger copper thicknesses, but are strikingly different near 1.0 nm copper thickness. This observation suggests that the GMR is affected by different factors depending on the thickness of the copper layer.Type of Medium: Electronic ResourceURL: -
7Articles: DFG German National LicensesPark, K. ; Salamanca-Riba, L. ; Jonker, B. T.
[S.l.] : American Institute of Physics (AIP)
Published 1996Staff ViewISSN: 1089-7550Source: AIP Digital ArchiveTopics: PhysicsNotes: Recently, there has been increased research activity on Fe-, Mn-, and Co-based diluted magnetic semiconductors (DMS) because of their interesting magneto-optical properties. Potential applications of DMS usually require thin films with a high degree of structural perfection, and high quality single crystal epilayers of Zn1−xFexSe and Zn1−xCoxSe have been grown by molecular beam epitaxy (MBE). In this work, the microstructural properties of (ZnSe/FeSe) and (ZnSe/MnSe) DMS superlattices grown on (001) GaAs substrates by MBE have been investigated using transmission electron microscopy. High-quality (ZnSe/FeSe) superlattices were grown by introducing a ZnSe buffer layer on the GaAs substrate prior to the growth of the superlattice. In contrast, nominal (ZnSe/FeSe) superlattices grown directly without a buffer layer on the substrate showed evidence for interdiffusion between the constituent layers of the superlattice. Chemical ordering of the Zn and Fe atoms was also observed in the resultant Zn1−xFexSe alloys along the [001] and [110] directions. This ordered structure corresponds to the CuAu–I type structure. In contrast, the (ZnSe/MnSe) superlattices did not show interdiffusion, but contained many microtwins and 60°-type misfit dislocations. The MnSe layer in the (ZnSe/MnSe) superlattices existed as a zinc-blende structure. © 1996 American Institute of Physics.Type of Medium: Electronic ResourceURL: -
8Articles: DFG German National LicensesStaff View
ISSN: 1089-7550Source: AIP Digital ArchiveTopics: PhysicsNotes: We have observed in-plane fourfold symmetry of the magnetization and magnetoresistance in Co/Cu multilayers electrodeposited on Si(001) substrates covered with a thin evaporated Cu seed layer. The fourfold symmetry correlates with the in-plane crystalline structure of the multilayers. High-angle x-ray diffraction shows that the Co/Cu multilayers have a strong (001) texture. Φ-scan x-ray diffraction reveals that the multilayers have fourfold symmetry in the plane with a 45° rotation with respect to the Si substrates. We estimated an anisotropy field of 98 mT from vector magnetization curves, which is in fairly good agreement with the value obtained from Co/Cu multilayers electrodeposited on (001) Cu single crystal substrates. The giant magnetoresistance appears to depend on the in-plane orientation of the multilayer due to the magnetocrystalline anisotropy. © 1998 American Institute of Physics.Type of Medium: Electronic ResourceURL: -
9Articles: DFG German National LicensesKuo, L. H. ; Salamanca-Riba, L. ; DePuydt, J. M. ; Cheng, H. ; Qiu, J.
Woodbury, NY : American Institute of Physics (AIP)
Published 1993Staff ViewISSN: 1077-3118Source: AIP Digital ArchiveTopics: PhysicsNotes: We have observed that undoped ZnSe films grown on GaAs substrates by molecular beam epitaxy show an irregular array of interfacial 60° misfit dislocations. However, N and Cl doping of the ZnSe thin films changes the interfacial dislocation structure. p-type ZnSe with N concentrations of ∼1018/cm3 shows a regular array of interfacial 60° misfit dislocations and a lower (∼1×106/cm2) density of threading dislocations compared to undoped films. However, samples with doping levels higher than 1019/cm3 show a density of threading dislocations of ∼108/cm2. These differences are explained in terms of Frank partial dislocations observed only in doped ZnSe. The Frank partial dislocations act as nucleation sites for the misfit dislocations. Thus, different mechanisms for the formation of misfit dislocations in doped and undoped films occur in this system.Type of Medium: Electronic ResourceURL: -
10Articles: DFG German National LicensesBeesabathina, D. Prasad ; Salamanca-Riba, L. ; Mao, S. N. ; Xi, X. X. ; Venkatesan, T.
Woodbury, NY : American Institute of Physics (AIP)
Published 1993Staff ViewISSN: 1077-3118Source: AIP Digital ArchiveTopics: PhysicsNotes: The morphology and microstructure of Nd1.85Ce0.15CuO4−y (NCCO) films grown epitaxially on (100) LaAlO3 (LAO) by pulsed laser deposition were studied by selected-area electron diffraction and high-resolution electron microscopy. The films were composed primarily of c-axis oriented grains and did not contain any polytypoidic faulting. The in-plane epitaxial relationship of the films was found to be [100]NCCO //[001]LAO. The Nd1.85Ce0.15CuO4−y-LaAlO3 interface is sharp and free of defects. A weak peak around the (110) position of NCCO(T') structure in x-ray diffraction was observed. Using microdiffraction and energy-dispersive x-ray analysis, we confirmed that this peak corresponds to the (004) reflection of cubic Ce0.5Nd0.5O1.75.Type of Medium: Electronic ResourceURL: -
11Articles: DFG German National LicensesPark, K. ; Salamanca-Riba, L. ; Jonker, B. T.
Woodbury, NY : American Institute of Physics (AIP)
Published 1992Staff ViewISSN: 1077-3118Source: AIP Digital ArchiveTopics: PhysicsNotes: We have observed chemical ordering in Zn1−xFexSe (x≈0.5) epilayers as well as in nominal (ZnSe/FeSe) superlattices along the [001] growth direction and the [110] direction using transmission electron microscopy. The ordered structure consists of alternating ZnSe and FeSe layers along the [001] and [110] directions. In nominal (ZnSe/FeSe) superlattices grown on (001) GaAs substrates, strain-induced interdiffusion between the layers takes place followed by ordering of the resultant Zn1−xFexSe alloys. Computer simulated images for a Zn0.5Fe0.5Se compound were obtained and compared with experimental images. To our knowledge, this is the first observation of ordering in a II-VI alloy.Type of Medium: Electronic ResourceURL: -
12Articles: DFG German National LicensesDahmani, R. ; Salamanca-Riba, L. ; Nguyen, N. V. ; Chandler-Horowitz, D. ; Jonker, B. T.
Woodbury, NY : American Institute of Physics (AIP)
Published 1994Staff ViewISSN: 1077-3118Source: AIP Digital ArchiveTopics: PhysicsNotes: Room-temperature spectroscopic ellipsometry measurements were carried out on ZnSe thin films grown on (001)GaAs substrates by molecular-beam epitaxy for the study of the lattice mismatch-induced strain at the interface. The magnitude of the absorption coefficient at the E0+Δ0 critical point is very sensitive to the strain in the film. The variation in the magnitude of the absorption coefficient is used to estimate the critical thickness for the onset of dislocation generation. Almost complete relaxation of the films was obtained for thicknesses higher than 500 nm. Also, the strain-induced coupling between the valence subbands was found to cause additional shifting of the light-hole subband.Type of Medium: Electronic ResourceURL: -
13Articles: DFG German National LicensesMao, S. N. ; Xi, X. X. ; Mao, Jian ; Wu, D. H. ; Li, Qi ; Anlage, S. M. ; Venkatesan, T. ; Beesabathina, D. Prasad ; Salamanca-Riba, L. ; Wu, X. D.
Woodbury, NY : American Institute of Physics (AIP)
Published 1994Staff ViewISSN: 1077-3118Source: AIP Digital ArchiveTopics: PhysicsNotes: We have grown superconducting Nd1.85Ce0.15CuO4−y (NCCO) thin films on (11¯02) sapphire using a yttria-stabilized zirconia (YSZ) buffer layer, which has been demonstrated to be the best material for the growth of n-type superconducting NCCO thin films. The films are c-axis oriented, epitaxially grown with a small mosaic spread of 0.2° and a Rutherford backscattering spectroscopy channeling yield of ∼9%. Cross-sectional transmission electron microscopy images reveal a sharp interface between NCCO and YSZ. The microwave surface resistance of NCCO films on YSZ buffered sapphire at 9.6 GHz is only 80 μΩ at 4.2 K in zero magnetic field, which is comparable to Y1Ba2Cu3O7−y films at similar reduced temperature, as a consequence of the decrease of structural imperfection in the film. The temperature dependence of the surface resistance and magnetic penetration depth in these films further confirms the s-wave BCS nature of NCCO.Type of Medium: Electronic ResourceURL: -
14Articles: DFG German National LicensesKuo, L. H. ; Salamanca-Riba, L. ; Wu, B. J. ; Hofler, G. ; DePuydt, J. M. ; Cheng, H.
Woodbury, NY : American Institute of Physics (AIP)
Published 1995Staff ViewISSN: 1077-3118Source: AIP Digital ArchiveTopics: PhysicsNotes: A systematic dependence of the density and type of stacking fault defects with substrate surface chemistry and film growth mode was observed in ZnSe-based films grown on GaAs substrates. Namely, the density of Frank-type stacking faults is very large for films grown on Ga-rich surfaces, but is very low for films grown on As-stabilized surfaces exposed to Zn prior to the growth of the film. In contrast, the density of Shockley-type stacking faults increases for films grown by 3D growth mode at the initial stages of growth, but decreases greatly if the films are grown by the layer-by-layer growth mode. Films with stacking fault densities as low as 104/cm2 were obtained by growing the films by the layer-by-layer growth on GaAs epilayers with As-stabilized surfaces that were exposed to Zn for 1–2 min prior to the growth of the films. © 1995 American Institute of Physics. [S0003-6951(95)00548-6]Type of Medium: Electronic ResourceURL: -
15Articles: DFG German National LicensesWu, B. J. ; DePuydt, J. M. ; Haugen, G. M. ; Höfler, G. E. ; Haase, M. A. ; Cheng, H. ; Guha, S. ; Qiu, J. ; Kuo, L. H. ; Salamanca-Riba, L.
Woodbury, NY : American Institute of Physics (AIP)
Published 1995Staff ViewISSN: 1077-3118Source: AIP Digital ArchiveTopics: PhysicsNotes: We report molecular beam epitaxial study of wide band gap ((approximately-greater-than)2.9 eV at room temperature) MgZnSSe on (001) oriented GaAs using ZnS, Mg, Zn, and Se sources. Although the growth is under group II rich condition, the compositions of S and Mg in the MgyZn1−ySxSe1−x are linear functions of flux ratios, PZnS/PSe and PMg/PZnS, up to 35%, respectively. Mirrorlike surface and low defect density (5×104 cm−2) MgZnSSe with band gap close to 3.1 eV can be achieved. Composition modulation, tweedlike contrasts and strain contrasts in the MgZnSSe are observed from transmission electron microscope analysis. For the first time, a miscibility gap at high S and Mg compositions is reported. Nitrogen-free radicals are used as the p-type dopant for the doping study. For the MgZnSSe with room-temperature band gap energy higher than 2.9 eV, the net acceptor concentration decreases as the band gap energy increases. © 1995 American Institute of Physics.Type of Medium: Electronic ResourceURL: -
16Articles: DFG German National LicensesMao, S. N. ; Jiang, Wu ; Xi, X. X. ; Li, Qi ; Peng, J. L. ; Greene, R. L. ; Venkatesan, T. ; Beesabathina, D. Prasad ; Salamanca-Riba, L. ; Wu, X. D.
Woodbury, NY : American Institute of Physics (AIP)
Published 1995Staff ViewISSN: 1077-3118Source: AIP Digital ArchiveTopics: PhysicsNotes: We have studied the oxygen doping effect in thin Nd1.85Ce0.15CuO4−y (NCCO) films. Contrary to the common believe that the disappearance of superconductivity in the over-reduced NCCO samples is a consequence of phase decomposition, we found that there exists an over-reduced region in which the crystallographic structure of the film remains essentially the same as in the optimum-oxygen doped region, but the film becomes insulating. Rutherford backscattering spectroscopy channeling analysis reveals that the oxygen over-reduction increases atomic distortion in the lattice. This work provides strong support to previous transport studies by Jiang et al. [Phys. Rev. Lett. 73, 1291 (1994)], which suggested the existence of both electron and hole carriers in superconducting NCCO. © 1995 American Institute of Physics.Type of Medium: Electronic ResourceURL: -
17Articles: DFG German National LicensesKuo, L. H. ; Salamanca-Riba, L. ; Wu, B. J. ; DePuydt, J. M. ; Haugen, G. M. ; Cheng, H. ; Guha, S. ; Haase, M. A.
Woodbury, NY : American Institute of Physics (AIP)
Published 1994Staff ViewISSN: 1077-3118Source: AIP Digital ArchiveTopics: PhysicsNotes: [100] composition modulation as well as [101] and [1¯01] tweed strain contrast were observed in lattice matched Zn1−xMgxSySe1−y epitaxial films grown on ZnSe buffer layers. The composition modulation corresponds to regions with different S and Mg concentration in a direction perpendicular to the growth direction. Very high quality lattice matched Zn1−xMgxSySe1−y films with a ZnSe quantum well were grown on As stabilized GaAs substrates exposed to Zn for a short time. The density of defects in these samples was less than 5×104/cm2. Other samples showed rough interfaces and high densities of Frank partial dislocations. The roughness is believed to result from an As-rich GaAs surface produced after the desorption of oxide under As overpressure.Type of Medium: Electronic ResourceURL: -
18Articles: DFG German National LicensesWu, B. J. ; Kuo, L. H. ; DePuydt, J. M. ; Haugen, G. M. ; Haase, M. A. ; Salamanca-Riba, L.
Woodbury, NY : American Institute of Physics (AIP)
Published 1996Staff ViewISSN: 1077-3118Source: AIP Digital ArchiveTopics: PhysicsNotes: We investigate the properties of II–VI short period superlattice (SPSL) blue light-emitting diodes grown by molecular beam epitaxy. The device consists of a ZnSe active layer, SPSL MgZnSSe cladding layers, and a ZnSeTe digital graded contact. The SPSL structure is made of alternating layers of MgSe, ZnSe, ZnS, and ZnSe. Highly ordered SPSL layer structures are successfully grown. Tweedlike contrast is observed in the pseudomorphic SPSL from our transmission electron microscopy analysis. The device shows high purity blue emission at 460 nm at room temperature with a 13 nm full width at half maximum. Operating at 14 A/cm2, the half-intensity lifetime is more than 13 h at room temperature with an external quantum efficiency of ∼0.1%. © 1996 American Institute of Physics.Type of Medium: Electronic ResourceURL: -
19Articles: DFG German National LicensesWu, B. J. ; Haugen, G. M. ; DePuydt, J. M. ; Kuo, L. H. ; Salamanca-Riba, L.
Woodbury, NY : American Institute of Physics (AIP)
Published 1996Staff ViewISSN: 1077-3118Source: AIP Digital ArchiveTopics: PhysicsNotes: We study the growth of pseudomorphic ZnSSe layers on GaAs. The dependence of the epilayer quality on Zn exposure to the GaAs surface is investigated. Zn treatment prior to the ZnSe buffer growth on the As-rich GaAs surface results in the lowest defect density. Transmission electron microscopy studies show that an atomic scale smooth interface is formed. Based on the etch pit density and photoluminescence image analysis, ZnSSe layers with defect density ≤1×104 cm−2 can be reproducibly obtained. © 1996 American Institute of Physics.Type of Medium: Electronic ResourceURL: -
20Articles: DFG German National LicensesLi, Hao ; Roytburd, A. L. ; Alpay, S. P. ; Tran, T. D. ; Salamanca-Riba, L. ; Ramesh, R.
Woodbury, NY : American Institute of Physics (AIP)
Published 2001Staff ViewISSN: 1077-3118Source: AIP Digital ArchiveTopics: PhysicsNotes: A series of heteroepitaxial BaxSr1−xTiO3 thin films with composition x=0.50 were deposited on (001) MgO substrates by pulsed-laser deposition. The thickness of the films was varied from 14 to 500 nm to produce a systematically decreasing level of in-plane tensile stresses. The microstructural and crystallographic features of the films were determined via transmission electron microscopy and x-ray diffraction. A theoretical treatment of the in-plane misfit strain as a function of film thickness is in agreement with the measured out-of-plane lattice parameters. Electrical measurements indicate a drop in the dielectric constant from 2350 for highly stressed thin films to 1700 for relaxed thicker films. The variation in the dielectric constant with the misfit strain is in accordance with a thermodynamic model developed. The relationship between the dielectric constant and electric field is also described by extending the thermodynamic model and taking the effect of electric field into account. A new definition of tunability is adopted to study the effect of strain on tunability. © 2001 American Institute of Physics.Type of Medium: Electronic ResourceURL: