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2 Dec 2002

Volume 81, Issue 23, pp. 4315-4476

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Origin of antiphase domain boundaries and their effect on the dielectric constant of Ba0.5Sr0.5TiO3 films grown on MgO substrates

Hao Li, H. Zheng, L. Salamanca-Riba, R. Ramesh, I. Naumov, and K. Rabe

Appl. Phys. Lett. 81, 4398 (2002); http://dx.doi.org/10.1063/1.1523632 (3 pages) | Cited 7 times

Online Publication Date: 25 November 2002

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Epitaxial Ba1−xSrxTiO3 (BST) with x = 0.5 films were grown on MgO substrates using pulsed-laser deposition. We have observed a high density of antiphase domain boundaries (ADB) in these BST films. We attribute the formation of the ADBs to the different crystal symmetry of the film and the substrate. Adjacent domains have an in plane phase shift of ½[110], or ½[1math0] thus creating a phase shift of the in plane lattice planes of ½[010] or ½[100] across the boundary. We have used first-principles calculations to obtain the effect of the ADBs on the dielectric constant of SrTiO3 and found that they lower the effective in plane dielectric constant in the direction normal to the ADB. Upon annealing, the density of ADBs decreases and the dielectric properties improve. © 2002 American Institute of Physics.
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68.55.-a Thin film structure and morphology
77.22.Ch Permittivity (dielectric function)
77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates
61.72.Ff Direct observation of dislocations and other defects (etch pits, decoration, electron microscopy, x-ray topography, etc.)

Tbit/inch2 ferroelectric data storage based on scanning nonlinear dielectric microscopy

Yasuo Cho, Kenjiro Fujimoto, Yoshiomi Hiranaga, Yasuo Wagatsuma, Atsushi Onoe, Kazuya Terabe, and Kenji Kitamura

Appl. Phys. Lett. 81, 4401 (2002); http://dx.doi.org/10.1063/1.1526916 (3 pages) | Cited 83 times

Online Publication Date: 25 November 2002

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Nanosized inverted domain dots in ferroelectric materials have potential applications in ultrahigh-density rewritable data storage systems. Here, a data storage system based on scanning nonlinear dielectric microscopy and thin films of ferroelectric single-crystal lithium tantalite is presented. Through domain engineering, nanosized inverted domain dots have been successfully formed at a data density of 1.50 Tbit/in.2. © 2002 American Institute of Physics.
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85.50.Gk Non-volatile ferroelectric memories
77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates
77.80.Dj Domain structure; hysteresis
77.55.-g Dielectric thin films

Correlation between infrared phonon modes and dielectric relaxation in Bi2O3–ZnO–Nb2O5 cubic pyrochlore

Juan C. Nino, Michael T. Lanagan, Clive A. Randall, and Stanislav Kamba

Appl. Phys. Lett. 81, 4404 (2002); http://dx.doi.org/10.1063/1.1524699 (3 pages) | Cited 29 times

Online Publication Date: 25 November 2002

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Analysis of the dielectric relaxation phenomena in Bi2O3–ZnO–Nb2O5 cubic pyrochlore utilizing the Arrhenius equation is revisited to include recent high-frequency measurements. The fitting parameters obtained are further analyzed by comparison with theoretical and experimental activation energies of better understood relaxation systems such as dipolar glasses and relaxor ferroelectrics. The attempt jump frequency obtained from the Arrhenius fit (ν0 ∼ 4.385 THz) is found in correspondence with the resonant frequencies of the polar phonon modes previously identified by infrared spectroscopy. This correlation, and in particular the role of the O–A–O and O′–A–O′ bending phonon modes in driving the relaxation, is discussed. © 2002 American Institute of Physics.
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77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates
77.22.Gm Dielectric loss and relaxation
63.20.D- Phonon states and bands, normal modes, and phonon dispersion

Supercritical carbon dioxide extraction to produce low-k plasma enhanced chemical vapor deposited dielectric films

J. A. Lubguban, J. Sun, T. Rajagopalan, B. Lahlouh, S. L. Simon, and S. Gangopadhyay

Appl. Phys. Lett. 81, 4407 (2002); http://dx.doi.org/10.1063/1.1525390 (3 pages) | Cited 4 times

Online Publication Date: 25 November 2002

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A treatment to reduce the dielectric constant of plasma enhanced chemical vapor deposition (PECVD) films is presented. The method involved extracting low molecular weight or CO2 soluble species in the films by post deposition supercritical CO2 pressurization (SCCO2). We observed a decrease in k value of about 10%–14% in a composite film of organosilicate and a-C:F after SCCO2 treatment at 200 °C for 8 h. The composite films were deposited by PECVD using C4F8 and tetravinyltetramethylcyclotetrasiloxane (TVTMCTS) liquid source and H2 carrier gas at room temperature. As-deposited films were also annealed at 200 °C for 8 h in N2 atmosphere to compare the effect of thermal annealing without SCCO2 treatment. The result shows that there is no change in the k of the films after annealing. Thus, SCCO2 extraction is a good method for reducing the dielectric constant of these PECVD composite films. Supercritical CO2 pressurization of the film deposited using TVTMCTS and H2 only without the addition of C4F8 has no effect on the dielectric properties of the film while SCCO2 treatment of a-C:F samples deposited using C4F8 only dissolved the film. Therefore, in the composite film, we expect that CFx species dissolve during SCCO2 treatment while the organosilicate structure is preserved. Analysis of the Fourier-transform infrared spectra of the samples supports this hypothesis based on the decrease in the C–F absorption intensity after SCCO2 treatment. © 2002 American Institute of Physics.
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77.84.Bw Elements, oxides, nitrides, borides, carbides, chalcogenides, etc.
77.55.-g Dielectric thin films
81.40.Tv Optical and dielectric properties related to treatment conditions
77.22.Ch Permittivity (dielectric function)
61.72.Cc Kinetics of defect formation and annealing
81.05.U- Carbon/carbon-based materials
52.77.Dq Plasma-based ion implantation and deposition
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
78.35.+c Brillouin and Rayleigh scattering; other light scattering
81.05.Rm Porous materials; granular materials
78.66.Nk Insulators

Kinetic of phase transformation of SrBi2Ta2O9 deposited by metalorganic decomposition on platinum electrodes

M. Moert, T. Mikolajick, G. Schindler, N. Nagel, W. Hartner, C. Dehm, H. Kohlstedt, and R. Waser

Appl. Phys. Lett. 81, 4410 (2002); http://dx.doi.org/10.1063/1.1526926 (3 pages) | Cited 2 times

Online Publication Date: 25 November 2002

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SrBi2Ta2O9 thin films were prepared by metalorganic decomposition on Pt/Ti/SiO2/Si substrates and subsequently crystallized at temperatures ranging from 600 to 700 °C for 40 to 225 min. Data of the Aurivillius surface coverage taken from atomic force microscopy measurements were used to model the kinetics of isothermal phase transformation from the fluorite to the Aurivillius phase. A two-dimensional growth mechanism at a decreasing nucleation rate can be deduced. By evaluating the temperature dependence of the growth rates, an activation energy for phase transformation of 318 kJ/mol is determined. © 2002 American Institute of Physics.
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77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates
77.55.-g Dielectric thin films
77.80.B- Phase transitions and Curie point
68.35.B- Structure of clean surfaces (and surface reconstruction)
68.37.Ps Atomic force microscopy (AFM)

Nanometer-scale pores in low-k dielectric films probed by positron annihilation lifetime spectroscopy

C. L. Wang, M. H. Weber, K. G. Lynn, and K. P. Rodbell

Appl. Phys. Lett. 81, 4413 (2002); http://dx.doi.org/10.1063/1.1526923 (3 pages) | Cited 13 times

Online Publication Date: 25 November 2002

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We measured positron annihilation lifetime spectra in mesoporous low dielectric constant (low-k) methyl-silsesquioxane (MSSQ) films versus porogen load Φ from Φ = 0% to 50%. The ortho-positronium lifetime parameters were obtained using both the maximum entropy and discrete lifetime analyses. Open and closed porosity distributions and the average radius of closed pores were obtained. The total porosity and the fraction of open/closed porosities were evaluated. The total porosity increases linearly with porogen load, consistent with the porosity obtained from density measurements. Open porosity occurs from 20% porogen load upwards. © 2002 American Institute of Physics.
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77.84.Jd Polymers; organic compounds
77.55.-g Dielectric thin films
78.70.Bj Positron annihilation
77.22.Ch Permittivity (dielectric function)

Effects of nitridation of silicon and repeated spike heating on the electrical properties of SrTiO3 gate dielectrics

Chih-Yi Liu, Hang-Ting Lue, and Tseung-Yuen Tseng

Appl. Phys. Lett. 81, 4416 (2002); http://dx.doi.org/10.1063/1.1526914 (3 pages) | Cited 13 times

Online Publication Date: 25 November 2002

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Electrical properties of SrTiO3 (STO) gate dielectrics on Si substrates grown by rf-magnetron sputtering were studied. We employed the surface nitridation and repeated spike heating to improve the interfacial properties of STO/Si. The nitrogen was moderately incorporated at the interface by first growing a thin SiON layer and then removing this sacrificial layer before growing STO gate dielectric. The experimental results indicate that this nitridation treatment may retard the formation of thin interfacial layer during the high-temperature growth of STO gate dielectric and consequently decrease the equivalent oxide thickness (EOT) by about 10% toward 24% at various deposition pressures. The STO gate dielectric with this nitridation treatment exhibited slightly lower leakage current at an accumulation region and nearly 2 orders of magnitude lower leakage current at an inversion region. The repeated spike heating technique was also employed to deposit a STO gate dielectric at repeated oscillating temperatures. The results show that this thermal treatment reduced the interfacial trap states and the leakage current was also reduced by about 1 order of magnitude at the same EOT. © 2002 American Institute of Physics.
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77.84.Bw Elements, oxides, nitrides, borides, carbides, chalcogenides, etc.
81.65.Lp Surface hardening: nitridation, carburization, carbonitridation
77.55.-g Dielectric thin films
81.40.Gh Other heat and thermomechanical treatments
61.72.Cc Kinetics of defect formation and annealing
68.35.Fx Diffusion; interface formation
68.37.Lp Transmission electron microscopy (TEM)
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