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3 Dec 2001

Volume 79, Issue 23, pp. 3749-3889

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Thermal stability of stacked high-k dielectrics on silicon

J. P. Chang and Y.-S. Lin

Appl. Phys. Lett. 79, 3824 (2001); http://dx.doi.org/10.1063/1.1419030 (3 pages) | Cited 38 times

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The thermal stability of ZrO2/ZrSixOy and ZrO2/ZrSixOy/SiNx thin films on silicon was examined by synchrotron radiation ultraviolet photoemission spectroscopy. The ZrO2/ZrSixOy layer deposited by atomic-layer-controlled deposition is stoichiometric, uniform, amorphous, and has an equivalent oxide thickness of ∼1 nm and a dielectric constant of ∼18 with low leakage current. These ZrO2/ZrSixOy samples are thermally stable in vacuum up to 880 °C at which the film decomposed to form ZrSi2, the most thermodynamically stable metal silicide at a per zirconium atom basis, and the desorption of SiO(g) and ZrO(g) accounted for the greatly reduced oxygen and zirconium photoemission intensities. The thermal stability of ZrO2/ZrSixOy is improved to 950 °C when deposited on a 0.5–0.7 nm SiNx film. © 2001 American Institute of Physics.
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77.84.Bw Elements, oxides, nitrides, borides, carbides, chalcogenides, etc.
77.55.-g Dielectric thin films
68.60.Dv Thermal stability; thermal effects
79.60.Dp Adsorbed layers and thin films
79.60.Ht Disordered structures
77.22.Ch Permittivity (dielectric function)
68.43.Vx Thermal desorption
65.60.+a Thermal properties of amorphous solids and glasses: heat capacity, thermal expansion, etc.

X-ray diffraction and Raman scattering study of SrBi2Ta2O9 ceramics and thin films with Bi3TiNbO9 addition

J. S. Zhu, H. X. Qin, Z. H. Bao, Y. N. Wang, W. Y. Cai, P. P. Chen, W. Lu, H. L. W. Chan, and C. L. Choy

Appl. Phys. Lett. 79, 3827 (2001); http://dx.doi.org/10.1063/1.1421642 (3 pages) | Cited 7 times

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Good ferroelectric properties have previously been reported for both the (1−x)SrBi2Ti2O9–xBi3TiNbO9 bulk ceramics and thin films. In this work, x-ray diffraction and Raman scattering were used to investigate the effect of the incorporation of Bi3TiNbO9 into SrBi2Ta2O9 bulk ceramics and thin films. A better crystallization, larger grain size and larger displacement of the Ta–O(4) or Ta–O(5) ions are the origin for the good ferroelectric properties of (1−x)SrBi2Ta2O9–xBi3TiNbO9 with x = 0.3–0.4. © 2001 American Institute of Physics.
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77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates
78.30.Hv Other nonmetallic inorganics
77.80.-e Ferroelectricity and antiferroelectricity
68.55.-a Thin film structure and morphology
85.50.Gk Non-volatile ferroelectric memories
63.20.-e Phonons in crystal lattices
78.66.Nk Insulators

Stress-induced depolarization of (Pb, La)TiO3 ferroelectric thin films by nanoindentation

M. Algueró, A. J. Bushby, M. J. Reece, R. Poyato, J. Ricote, M. L. Calzada, and L. Pardo

Appl. Phys. Lett. 79, 3830 (2001); http://dx.doi.org/10.1063/1.1418258 (3 pages) | Cited 14 times

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Electrical depolarization has been observed in lanthanum-modified lead titanate ferroelectric thin films stressed by nanoindentation. A spherical metallic indenter was used as a top electrode to locally pole the films and then to measure the depolarization current intensity. The current intensity had distinctive maxima at given indentation forces. These are related to the stress thresholds for the depolarization mechanism, which is probably 90° domain wall movements. Knowledge of the depolarization stresses is necessary for the design of microelectromechanical systems that include a ferroelectric layer. © 2001 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
77.22.Ej Polarization and depolarization
68.60.Bs Mechanical and acoustical properties
85.85.+j Micro- and nano-electromechanical systems (MEMS/NEMS) and devices
77.80.Dj Domain structure; hysteresis
62.20.M- Structural failure of materials

Effects of tantalum adhesion layer on the properties of SrBi2Ta2O9 ferroelectric thin films

Ching-Chich Leu, Ming-Che Yang, Chen-Ti Hu, Chao-Hsin Chien, Ming-Jui Yang, and Tiao-Yuan Huang

Appl. Phys. Lett. 79, 3833 (2001); http://dx.doi.org/10.1063/1.1423405 (3 pages) | Cited 10 times

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The effects of tantalum (Ta) adhesion layer on the ferroelectric and microstructural properties of sol-gel-derived SrBi2Ta2O9 (SBT) films are reported in this study. Compared to the traditional titanium (Ti) adhesion layer, the Ta adhesion layer results in more favorable, highly (115) textural structure of SBT films and therefore higher polarization and dielectric constant. The remnant polarization value of the SBT films crystallized at 750 °C increases from 11.1 to 14.2 μC/cm2 at 5 V, and the dielectric constant increases from 175 to 225. The observed improvement in the electrical properties of SBT films is ascribed to the superior microstructure of Pt thin film on Ta, which has been characterized by x-ray diffraction spectrum (XRD). XRD patterns clearly indicate that the Ti adhesion layer favors c-axis crystalline structure that is undesirable for ferroelectric properties. Moreover, secondary ion mass spectrometer profiles strongly indicate that Ti atoms diffuse deeply into the bulk of SBT thin films after crystallization annealing. By using Ta as the adhesion layer material, this inhomogeneous interdiffusion phenomenon can be effectively suppressed, eliminating the formation of TiOx interfacial layer, and possibly decreasing the occurrence of undesirable second phase compound. © 2001 American Institute of Physics.
Show PACS
77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates
68.35.Np Adhesion
77.22.Ch Permittivity (dielectric function)
77.22.Ej Polarization and depolarization
61.72.Cc Kinetics of defect formation and annealing
77.55.-g Dielectric thin films
68.55.-a Thin film structure and morphology

Soft phonon modes in Ba0.5Sr0.5TiO3 thin films studied by Raman spectroscopy

D. A. Tenne, A. M. Clark, A. R. James, K. Chen, and X. X. Xi

Appl. Phys. Lett. 79, 3836 (2001); http://dx.doi.org/10.1063/1.1424463 (3 pages) | Cited 18 times

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We have studied vibrational properties of Ba0.5Sr0.5TiO3 thin films grown by pulsed laser deposition on SrTiO3 and LaAlO3 substrates with SrRuO3 buffer layers by Raman spectroscopy over the temperature range from 5 to 300 K. The soft phonon modes were observed. The temperature dependence of the soft phonon frequency and the splitting of the triply degenerated soft mode into two components of A and E symmetries indicate the ferroelectric phase transition. The E soft mode is overdamped over a broad range of temperatures, and the A soft mode intensity decreases gradually in this range. This indicates a broad ferroelectric phase transition in the thin films. A comparison of results obtained from films deposited on SrTiO3 and LaAlO3 substrates shows that strain shifts the ferroelectric phase transition temperatures. © 2001 American Institute of Physics.
Show PACS
77.55.-g Dielectric thin films
77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates
78.66.Nk Insulators
63.22.-m Phonons or vibrational states in low-dimensional structures and nanoscale materials
77.80.B- Phase transitions and Curie point
81.15.Fg Pulsed laser ablation deposition
78.30.Hv Other nonmetallic inorganics
63.70.+h Statistical mechanics of lattice vibrations and displacive phase transitions

Temperature increase and charging current in polyethylene film during application of high voltage

Chao Zhang, Kazue Kaneko, and Teruyoshi Mizutani

Appl. Phys. Lett. 79, 3839 (2001); http://dx.doi.org/10.1063/1.1421625 (3 pages)

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Temperature increase in a low density polyethylene film during the application of high dc voltage was estimated by measuring the sound velocity with a pulsed electroacoustic method. The temperature shows no change under the electric field of 50 MVm−1 at ambient temperature of 30 °C. However, the temperature increases with time, and rises to 63.7 °C in 90 min of the voltage application at ambient temperature of 60 °C. The temperature increase was caused by Joule heating and it resulted in the increase of charging current during the application of high dc voltage. The increase in charging current calculated from the temperature increase agreed well with the experimental one. © 2001 American Institute of Physics.
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73.61.Ph Polymers; organic compounds
62.65.+k Acoustical properties of solids
73.50.Rb Acoustoelectric and magnetoacoustic effects
77.55.-g Dielectric thin films
77.84.Jd Polymers; organic compounds

Higher-order nonlinear dielectric microscopy

Yasuo Cho and Koya Ohara

Appl. Phys. Lett. 79, 3842 (2001); http://dx.doi.org/10.1063/1.1421645 (3 pages) | Cited 17 times

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A higher-order nonlinear dielectric microscopy technique with higher lateral resolution than conventional nonlinear dielectric imaging is investigated. The proposed scheme involves the measurement of higher-order nonlinear dielectric constants, with sensitivity to the first 0.75 nm in depth for LiNbO3 substrate surface. This technique is demonstrated to be very useful for observing surface layers of the order of unit cell thickness on ferroelectric materials. © 2001 American Institute of Physics.
Show PACS
77.80.-e Ferroelectricity and antiferroelectricity
77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates
77.55.-g Dielectric thin films
77.22.Ch Permittivity (dielectric function)
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