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11 Feb 2002

Volume 80, Issue 6, pp. 905-1104

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In-plane bandgap control in porous GaN through electroless wet chemical etching

Xiuling Li, Young-Woon Kim, Paul W. Bohn, and Ilesanmi Adesida

Appl. Phys. Lett. 80, 980 (2002); http://dx.doi.org/10.1063/1.1448860 (3 pages) | Cited 38 times

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Nanoporous GaN structures were formed from crystalline GaN on conducting SiC substrate using metal-assisted electroless etching in HF/H2O2. Morphology varies as a function of etch time and solution parameters. The resulting porous GaN (PGaN) displays cathodoluminescence (CL) with two bands blue-shifted from the bulk bandgap energy by 103 meV and 352 meV, respectively. Appearance of the blueshifted emission is correlated with the development of highly anisotropic wire-like structures in the morphology, with the higher energy CL band arising from the portion of the structure with the smallest feature sizes. These observations suggest that the blueshifted emission arises from quantum confinement effects. CL imaging indicates that the blueshifted emission is spatially segregated from the band gap emission. Variations in morphology and light emission properties apparent between Pt-coated and uncoated areas likely arise from hole transport and access of solution reagents to the GaN interface. © 2002 American Institute of Physics.
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71.20.Nr Semiconductor compounds
81.05.Rm Porous materials; granular materials
78.60.Hk Cathodoluminescence, ionoluminescence
81.65.Cf Surface cleaning, etching, patterning
61.66.Fn Inorganic compounds
61.43.Gt Powders, porous materials

Optical properties of inorganic (SiO2)1−x(Nd2O3)x alloy films for the color filter of plasma display panel

D. K. Lee, S. M. Seo, S. G. Lee, S. H. Sohn, S. H. Park, and H. M. Kim

Appl. Phys. Lett. 80, 983 (2002); http://dx.doi.org/10.1063/1.1448662 (3 pages) | Cited 2 times

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In order to improve the primary color purity of the plasma display panel (PDP), inorganic (SiO2)1−x(Nd2O3)x alloy films have been fabricated by the rf-magnetron sputtering method, and their optical properties have been investigated as functions of Nd2O3 contents in films and thickness of films. The study has revealed that absorption in (SiO2)1−x(Nd2O3)x films is due to intratransition within the 4f shell of the Nd3+ ion, and that it becomes larger with increasing Nd3+ ion concentrations in films and film thickness. In the PDP devices with our band rejection color filters, luminances from neon gas discharge itself and sidebands of phosphors are sufficiently reduced, resulting in wider color gamut and higher color purity. © 2002 American Institute of Physics.
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42.79.Ci Filters, zone plates, and polarizers
85.60.Pg Display systems
52.75.-d Plasma devices
78.66.Nk Insulators
42.79.Kr Display devices, liquid-crystal devices
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Ohmic contacts to p-type GaN mediated by polarization fields in thin InxGa1−xN capping layers

T. Gessmann, Y.-L. Li, E. L. Waldron, J. W. Graff, E. F. Schubert, and J. K. Sheu

Appl. Phys. Lett. 80, 986 (2002); http://dx.doi.org/10.1063/1.1445807 (3 pages) | Cited 29 times

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Low-resistance ohmic contacts are demonstrated using thin p-type InGaN layers on p-type GaN. It is shown that the tunneling barrier width is drastically reduced by polarization-induced electric fields in the strained InGaN capping layers resulting in an increase of the hole tunneling probability through the barrier and a significant decrease of the specific contact resistance. The specific contact resistance of Ni (10 nm)/Au (30 nm) contacts deposited on the InGaN capping layers was determined by the transmission line method. Specific contact resistances of 1.2×10−2 Ω cm2 and 6×10−3 Ω cm2 were obtained for capping layer thicknesses of 20 nm and 2 nm, respectively. © 2002 American Institute of Physics.
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73.40.Ns Metal-nonmetal contacts
73.40.Cg Contact resistance, contact potential
73.40.Gk Tunneling

Near-field photoluminescence spectroscopy of InGaN films grown by molecular-beam epitaxy

Jeongyong Kim, Kevan Samiee, Jeffrey O. White, Jae-Min Myoung, and Kyekyoon Kim

Appl. Phys. Lett. 80, 989 (2002); http://dx.doi.org/10.1063/1.1446206 (3 pages) | Cited 13 times

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The spatial and spectral distribution of photoluminescence from InGaN films grown by plasma-assisted molecular-beam epitaxy are studied by near-field scanning optical microscopy. The luminescence intensity is low in the vicinity of pits in the surface that are believed to be associated with dislocations. For 20% In, the emission is random on a submicron length scale, but clumps into micron-sized regions at 27% In. The clustering is quantified by calculating the image entropy. Near-field spectra indicate that the regions of high intensity are not due to a local increase in In. Spatial variations in the luminescence wavelength indicate that composition fluctuations are enhanced with increasing In. © 2002 American Institute of Physics.
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78.66.Fd III-V semiconductors
78.55.Cr III-V semiconductors
81.05.Ea III-V semiconductors
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
68.37.Uv Near-field scanning microscopy and spectroscopy
68.35.B- Structure of clean surfaces (and surface reconstruction)
61.72.Hh Indirect evidence of dislocations and other defects (resistivity, slip, creep, strains, internal friction, EPR, NMR, etc.)
61.72.Lk Linear defects: dislocations, disclinations
52.77.Dq Plasma-based ion implantation and deposition
81.15.Jj Ion and electron beam-assisted deposition; ion plating
65.40.G- Other thermodynamical quantities
61.66.Bi Elemental solids
61.66.Dk Alloys
68.55.A- Nucleation and growth

Transport properties of the advancing interface ohmic contact to AlGaN/GaN heterostructures

D. Qiao, L. S. Yu, L. Jia, P. M. Asbeck, S. S. Lau, and T. E. Haynes

Appl. Phys. Lett. 80, 992 (2002); http://dx.doi.org/10.1063/1.1447591 (3 pages) | Cited 30 times

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The transport properties of the advancing interface ohmic contact to AlGaN/GaN heterostructure field-effect transistors have been investigated. We found that carrier transport across the AlGaN barrier layer is dominated by the tunneling of electrons that originate from the two-dimensional electron gas located at the AlGaN/GaN interface. The observed temperature dependence of the specific contact resistivity is different from that of the contact on highly doped bulk semiconductors, although tunneling current dominates the carrier transport in both cases. © 2002 American Institute of Physics.
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85.30.Tv Field effect devices
73.40.Ns Metal-nonmetal contacts
73.40.Cg Contact resistance, contact potential
73.40.Gk Tunneling
85.30.De Semiconductor-device characterization, design, and modeling
73.20.At Surface states, band structure, electron density of states

Electronic characterization of n-ScN/p+ Si heterojunctions

F. Perjeru, X. Bai, and M. E. Kordesch

Appl. Phys. Lett. 80, 995 (2002); http://dx.doi.org/10.1063/1.1447323 (3 pages) | Cited 2 times

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We report the electronic characterization of n-ScN in heterojunctions, including deep level transient spectroscopy of electrically active deep levels. ScN material has been grown by plasma assisted physical vapor deposition on commercial p+ Si substrates. Current–voltage and capacitance–voltage measurements indicate that the built-in voltages for the heterojunctions used in this study are approximately 1.74 and 0.40 eV, as seen by electrons and holes. Deep level transient spectroscopy results show the presence of an electronic trap with activation energy EC−ET = 0.51 eV. The trap has a higher concentration (1.2–1.6×1013 cm−3) closer to the ScN/Si interface. © 2002 American Institute of Physics.
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73.20.Hb Impurity and defect levels; energy states of adsorbed species
73.40.Lq Other semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping
73.50.Gr Charge carriers: generation, recombination, lifetime, trapping, mean free paths

Scattering of the charge carriers by ordered arrays of defect pairs in ternary chalcopyrite semiconductors

C. Rincón, S. M. Wasim, and G. Marín

Appl. Phys. Lett. 80, 998 (2002); http://dx.doi.org/10.1063/1.1447597 (3 pages) | Cited 10 times

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The electrical properties of CuIn3Se5, CuGa3Te5, and CuIn3Te5 that contain arrays of donor–acceptor defect pairs (DADPs) in the lattice structure are studied. An expression for the scattering of the charge carriers with the DADPs, calculated from simple first principles, is proposed. This, when combined with other well-established mechanisms, explains the temperature dependence of the relatively low carrier mobility in these compounds in the activation regime very well. © 2002 American Institute of Physics.
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72.20.Fr Low-field transport and mobility; piezoresistance
72.20.My Galvanomagnetic and other magnetotransport effects
72.10.Fk Scattering by point defects, dislocations, surfaces, and other imperfections (including Kondo effect)
71.55.Ht Other nonmetals
72.20.Dp General theory, scattering mechanisms

Strong acceptor density and temperature dependences of thermal activation energy of acceptors in a Mg-doped GaN epilayer grown by metalorganic chemical-vapor deposition

M. G. Cheong, K. S. Kim, C. S. Kim, R. J. Choi, H. S. Yoon, N. W. Namgung, E.-K. Suh, and H. J. Lee

Appl. Phys. Lett. 80, 1001 (2002); http://dx.doi.org/10.1063/1.1448666 (3 pages) | Cited 12 times

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P-type GaN layers were grown on sapphire by metalorganic chemical-vapor deposition and then rapid thermal annealing (RTA) was performed to electrically activate Mg impurities. Varied acceptor densities were obtained by RTA temperature and Mg concentration. Temperature-dependent Hall effects show that the thermal activation energy of the acceptor (EA) is strongly dependent on the acceptor density (NA), approximated by EA(0) = 372−1.16×10−18 NA meV at 0 K. A strong temperature dependence of EA was also obtained in this study. © 2002 American Institute of Physics.
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71.55.Eq III-V semiconductors
73.61.Ey III-V semiconductors
61.72.Cc Kinetics of defect formation and annealing
61.80.Ba Ultraviolet, visible, and infrared radiation effects (including laser radiation)
72.20.My Galvanomagnetic and other magnetotransport effects
72.80.Ey III-V and II-VI semiconductors
81.05.Ea III-V semiconductors

Simulation of gallium arsenide electroluminescence spectra in avalanche breakdown using self-absorption and recombination models

M. Lahbabi, A. Ahaitouf, E. Abarkan, M. Fliyou, A. Hoffmann, J.-P. Charles, Bharat L. Bhuva, S. E. Kerns, and D. V. Kerns

Appl. Phys. Lett. 80, 1004 (2002); http://dx.doi.org/10.1063/1.1447322 (3 pages) | Cited 3 times

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Light emission from gallium arsenide (GaAs) p–n junctions biased in avalanche breakdown have been modeled over the range of 1.4–3.4 eV. The model emphasizes direct and indirect recombination processes and bulk self-absorption. Comparisons between measured and simulated spectra for sample junctions from custom and commercially fabricated GaAs devices demonstrate that the model is simple, accurate, and consistent with fundamental physical device theory. The model also predicts the junction depth with accuracy. © 2002 American Institute of Physics.
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78.60.Fi Electroluminescence
78.66.Fd III-V semiconductors
77.22.Jp Dielectric breakdown and space-charge effects
73.50.Fq High-field and nonlinear effects
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping
73.50.Gr Charge carriers: generation, recombination, lifetime, trapping, mean free paths
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Nonlinear dielectric microwave losses in MgO substrates

M. A. Hein, D. E. Oates, P. J. Hirst, R. G. Humphreys, and A. V. Velichko

Appl. Phys. Lett. 80, 1007 (2002); http://dx.doi.org/10.1063/1.1447000 (3 pages) | Cited 23 times

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We have investigated the nonlinear surface impedance and two-tone intermodulation distortion of ten epitaxial YBa2Cu3O7−δ films on MgO substrates, using stripline resonators, at frequencies f = 2.3–11.2 GHz and temperatures T = 1.7 K−TC. The power dissipation decreased by up to one order of magnitude as the microwave electric field was increased to 100 V/m for T<20 K. The reactance showed only a weak increase. The minimum of the losses correlated with a plateau in the intermodulation signal. The same features were observed for a Nb film on MgO but not for YBa2Cu3O7−δ and Nb on LaAlO3 or sapphire. The anomalous response results from dielectric losses in MgO, most probably due to defect dipole relaxation. © 2002 American Institute of Physics.
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74.78.-w Superconducting films and low-dimensional structures
74.72.-h Cuprate superconductors
74.25.N- Response to electromagnetic fields
77.22.Gm Dielectric loss and relaxation

Manipulation of single vortices in YBa2Cu3O6.354 with a locally applied magnetic field

Brian W. Gardner, Janice C. Wynn, D. A. Bonn, Ruixing Liang, W. N. Hardy, John R. Kirtley, Vladimir G. Kogan, and Kathryn A. Moler

Appl. Phys. Lett. 80, 1010 (2002); http://dx.doi.org/10.1063/1.1445468 (3 pages) | Cited 22 times

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We demonstrate the controlled, reversible manipulation of individual vortices in a superconductor with a locally applied magnetic field. The local field is supplied by a field coil on a superconducting quantum interference device (SQUID). The SQUID is used to image the vortices before and after moving. This device can be used both to push individual vortices and to create individual vortex–antivortex pairs. We calculate the force applied on a rigid vortex and find that ∼ 0.5 pN is necessary to move vortices in underdoped single crystals of YBa2Cu3O6.354 with Tc ∼  12 K. © 2002 American Institute of Physics.
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74.25.Uv Vortex phases (includes vortex lattices, vortex liquids, and vortex glasses)
74.72.-h Cuprate superconductors

Carrier-enhanced ferromagnetism in Ge1−xMnxTe

Y. Fukuma, H. Asada, M. Arifuku, and T. Koyanagi

Appl. Phys. Lett. 80, 1013 (2002); http://dx.doi.org/10.1063/1.1445477 (3 pages) | Cited 24 times

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We have studied the dependence of magnetic properties on the carrier concentration of IV–VI diluted magnetic semiconductor Ge1−xMnxTe prepared by ionized-cluster beam technique. With increasing carrier concentration, the magnetic properties drastically change; saturation magnetization increases and coercive field decreases in hysteresis loop, and the Curie temperature increases. These results obviously show carrier-enhanced ferromagnetic order. The similar effect is also observed in magnetoresistance behavior. © 2002 American Institute of Physics.
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75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
75.30.Kz Magnetic phase boundaries (including classical and quantum magnetic transitions, metamagnetism, etc.)
75.50.Dd Nonmetallic ferromagnetic materials
75.50.Pp Magnetic semiconductors
72.20.My Galvanomagnetic and other magnetotransport effects
72.80.Jc Other crystalline inorganic semiconductors

Strong pinning in ternary (Nd–Sm–Gd)Ba2Cu3Oy superconductors

M. Muralidhar, S. Nariki, M. Jirsa, Y. Wu, and M. Murakami

Appl. Phys. Lett. 80, 1016 (2002); http://dx.doi.org/10.1063/1.1447582 (3 pages) | Cited 14 times

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We have studied the flux pinning in melt-textured (Nd0.33Sm0.33Gd0.33)Ba2Cu3Oy NSG-123 superconductors with various numbers of Gd2BaCuO5 (Gd-211) particles. Transmission electron microscopy (TEM) showed that submicron Gd-211 particles are uniformly distributed in the superconductive matrix. Dark-field TEM observations further showed that a high density of RE rich RE1+xBa2−xCu3Oy (RE-123ss) clusters 3–10 nm in size were distributed in the NSG-123 matrix. A strongly developed fishtail was observed in the magnetization hysteresis loops of all the samples. A critical current density of 100 kA/cm2 (77 K) was achieved at the secondary peak field of 2 T for the H∥ c axis in the NSG-123 sample with 10 mol % Gd-211. Large grain NSG-123 pellets with 30 mol % Gd-211 and 20 wt % AgO2, 30 mm in diameter and 15 mm in height, exhibited a single-cone profile with a peak value of 1.2 T at 77 K. A higher trapped-field value of 1.5 T was recorded at 2 T, reflecting the secondary peak effect. © 2002 American Institute of Physics.
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74.72.-h Cuprate superconductors
74.25.Uv Vortex phases (includes vortex lattices, vortex liquids, and vortex glasses)
74.25.Ha Magnetic properties including vortex structures and related phenomena
74.25.Sv Critical currents

Superconductivity of Ca(Al0.5,Si0.5)2, a ternary silicide with the AlB2-type structure

Motoharu Imai, Kenji Nishida, Takashi Kimura, and Hideki Abe

Appl. Phys. Lett. 80, 1019 (2002); http://dx.doi.org/10.1063/1.1448857 (3 pages) | Cited 49 times

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A ternary silicide Ca(Al0.5,Si0.5)2 was prepared by Ar arc melting. Powder x-ray diffraction measurement indicates that it has the AlB2-type structure with lattice constants of a = 4.1905(5) and c = 4.3992(8) Å, where Si and Al atoms are arranged in the disordered honeycomb lattice and Ca atoms are intercalated between them. The silicide is isostructural with a superconductor MgB2. Electrical resistivity and dc magnetization measurements revealed that it is a superconductor with a TC of 7.7 K. © 2002 American Institute of Physics.
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74.70.Ad Metals; alloys and binary compounds (including A15, MgB2, etc.)
74.25.F- Transport properties
74.25.Ha Magnetic properties including vortex structures and related phenomena
61.66.Dk Alloys
74.10.+v Occurrence, potential candidates
61.50.Lt Crystal binding; cohesive energy

Submicron YBa2Cu3Ox ramp Josephson junctions

Philippe V. Komissinski, Björn Högberg, Alexander Ya. Tzalenchuk, and Zdravko Ivanov

Appl. Phys. Lett. 80, 1022 (2002); http://dx.doi.org/10.1063/1.1448176 (3 pages) | Cited 10 times

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Submicron YBa2Cu3Ox/PrBa2Cu2.6Ga0.4Ox/YBa2Cu3Ox ramp-type Josephson junctions were fabricated and tested. The submicron bridges in the top electrode were patterned by e-beam lithography and Ar ion milling through an amorphous carbon (a-C) mask. Junctions with width ranging from 0.2 to 8 μm and oriented along different crystal directions of YBa2Cu3Ox have been produced. Current–voltage characteristics show a behavior consistent with the resistively shunted junction model with small excess current. Junction critical current densities of about 10 kA/cm2 and characteristic voltages up to 6 mV were measured at 4.2 K for the submicron junctions. Junctions along different crystal orientations showed different characteristics suggesting an influence from the d-wave order parameter. © 2002 American Institute of Physics.
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74.50.+r Tunneling phenomena; Josephson effects
74.72.-h Cuprate superconductors
74.25.Sv Critical currents

Shapiro steps observed in a dc superconducting quantum interference device with multiple junctions in each arm

L. Chen, P. Chen, and C. K. Ong

Appl. Phys. Lett. 80, 1025 (2002); http://dx.doi.org/10.1063/1.1447598 (3 pages) | Cited 4 times

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A high-Tc dc superconducting quantum interference device (SQUID) with three Josephson junctions (JJs) in series in each of its arms has been fabricated. Its Shapiro steps were studied using microwave (rf) radiation of 10 GHz and weak magnetic fields. The appearance of giant Shapiro steps and of some of half-integer steps was observed. Separation between the adjacent Shapiro steps could be tuned by rf magnetic fields and small external dc magnetic fields. This phenomenon was analyzed by phase locking the JJs in the SQUID. © 2002 American Institute of Physics.
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85.25.Dq Superconducting quantum interference devices (SQUIDs)
74.50.+r Tunneling phenomena; Josephson effects
85.25.Cp Josephson devices
74.25.N- Response to electromagnetic fields

Enhanced magnetization of nanostructured granular Ni/[Cu(II)–C–O] films

G. M. Chow, J. Ding, and J. Zhang

Appl. Phys. Lett. 80, 1028 (2002); http://dx.doi.org/10.1063/1.1447599 (3 pages) | Cited 3 times

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Enhanced saturation magnetization was observed in granular nanostructured Ni/[Cu(II)–O–C] films deposited by the nonaqueous, electroless polyol process. The saturation magnetization of Ni–Cu complex films at room temperature was 112 emu/g, which was about two times that of bulk Ni (54.4 emu/g). It is suggested that the enhancement was caused by the magnetic interaction between the Ni particles and the amorphous Cu(II) complex. The observed shifted Curie temperature, large anisotropy field, and strong temperature dependence of saturation magnetization support this argument. © 2002 American Institute of Physics.
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75.70.Ak Magnetic properties of monolayers and thin films
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
75.50.Tt Fine-particle systems; nanocrystalline materials
75.30.Gw Magnetic anisotropy
75.30.Kz Magnetic phase boundaries (including classical and quantum magnetic transitions, metamagnetism, etc.)
78.70.Dm X-ray absorption spectra
79.60.-i Photoemission and photoelectron spectra

Direct observation of photoinduced magnetization in a relaxor ferromagnet

Y. Okimoto, Y. Ogimoto, M. Matsubara, Y. Tomioka, T. Kageyama, T. Hasegawa, H. Koinuma, M. Kawasaki, and Y. Tokura

Appl. Phys. Lett. 80, 1031 (2002); http://dx.doi.org/10.1063/1.1448854 (3 pages) | Cited 25 times

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Persistent ferromagnetic magnetization (M) as large as 0.6 μB per Mn site can be induced by irradiating visible laser pulses on a thin film of 1% Cr-doped Pr0.5Ca0.5MnO3. The enhancement of M upon the photoexcitation was also confirmed by the scanning superconducting quantum interference device microscope as an increase of magnetic field from ferromagnetic domains. The observed photoinduced transition from a metastable charge/orbital ordered state into a ferromagnetic one is likely to be assisted by the microscopic phase separation characteristic of such a relaxor ferromagnet as the present Cr-doped manganite. © 2002 American Institute of Physics.
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75.70.Ak Magnetic properties of monolayers and thin films
75.50.Dd Nonmetallic ferromagnetic materials
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
75.30.Kz Magnetic phase boundaries (including classical and quantum magnetic transitions, metamagnetism, etc.)
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Dielectric loss modes of SrTiO3 thin films deposited on different substrates

Zhi Yu, Chen Ang, Ruyan Guo, A. S. Bhalla, and L. E. Cross

Appl. Phys. Lett. 80, 1034 (2002); http://dx.doi.org/10.1063/1.1445482 (3 pages) | Cited 23 times

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The dielectric loss modes of SrTiO3 thin films deposited on different substrates are reported. Two dielectric loss modes around 165 and 75 K (at 10 kHz) with field-independent Tm are emphasized. The physical origin of the dielectric modes is discussed and is tentatively attributed to the motion of oxygen vacancies. © 2002 American Institute of Physics.
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77.55.-g Dielectric thin films
77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates
77.22.Gm Dielectric loss and relaxation
81.15.Fg Pulsed laser ablation deposition

X-ray-induced phase transformation in congruent and vapor-transport-equilibrated lithium tantalate and lithium niobate

V. Ya. Shur, E. B. Blankova, E. L. Rumyantsev, E. V. Nikolaeva, E. I. Shishkin, A. V. Barannikov, R. K. Route, M. M. Fejer, and R. L. Byer

Appl. Phys. Lett. 80, 1037 (2002); http://dx.doi.org/10.1063/1.1447602 (3 pages) | Cited 2 times

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We have discovered an effect of a partially reversible x-ray-induced increase of diffuse x-ray scattering in both congruent and vapor-transport equilibrated single-crystalline lithium niobate and lithium tantalate. The effect has been attributed to x-ray-induced decay of the ferroelectric phase at room temperature. The x-ray-induced change of the switching current and hysteresis loops observed is in accord with this assumption. © 2002 American Institute of Physics.
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77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates
77.80.B- Phase transitions and Curie point
77.80.Fm Switching phenomena
77.80.Dj Domain structure; hysteresis
61.80.Cb X-ray effects
78.70.Ck X-ray scattering
77.55.-g Dielectric thin films

Anisotropic ferroelectric properties of epitaxially twinned Bi3.25La0.75Ti3O12 thin films grown with three different orientations

Ho Nyung Lee and Dietrich Hesse

Appl. Phys. Lett. 80, 1040 (2002); http://dx.doi.org/10.1063/1.1447321 (3 pages) | Cited 74 times

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Epitaxially twinned (001)- , (118)- , and (104)-oriented La-substituted Bi4Ti3O12 (BLT) ferroelectric films have been grown by pulsed laser deposition on (001)- , (011)- , and (111)-oriented SrTiO3 single-crystal substrates, respectively, covered with SrRuO3. Well-defined (001)-oriented BLT films were grown at a substrate temperature as low as 600 °C. By x-ray diffraction characterization it has been found that the low-index three-dimensional epitaxial orientation relationship BLT(001)‖SrRuO3(001)‖SrTiO3(001); BLT[1math0]‖SrRuO3[100]‖SrTiO3[100] is valid for all epitaxially twinned BLT thin films grown on SrRuO3-covered SrTiO3 substrates in spite of their different orientations. The (104)-oriented BLT films showed an about 1.5 times higher remanent polarization (2Pr = 31.9 μC/cm2) than the (118)-oriented BLT films (2Pr = 20.7 μC/cm2), while (001)-oriented BLT films revealed only a small polarization component (2Pr = 1.1 μC/cm2), thus demonstrating the ferroelectric anisotropy. © 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
81.15.Fg Pulsed laser ablation deposition
77.80.Dj Domain structure; hysteresis
77.22.Ej Polarization and depolarization

Coercive field of 0.955Pb(Zn1/3Nb2/3)O3–0.045PbTiO3 single crystal and its frequency dependence

Jianhua Yin and Wenwu Cao

Appl. Phys. Lett. 80, 1043 (2002); http://dx.doi.org/10.1063/1.1448385 (3 pages) | Cited 12 times

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Domain switching behavior of 0.955Pb(Zn1/3Nb2/3)O3–0.045PbTiO3 ferroelectric single crystal has been investigated using the ultrasonic technique in addition to the polarization hysteresis measurements. The ultrasonic technique makes it possible to extend the coercive field measurement to frequencies as low as 10−5 Hz, revealing the existence of a saturated coercive field Esc, which representing the intrinsic switching barrier. © 2002 American Institute of Physics.
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77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates
77.80.Fm Switching phenomena
77.80.Dj Domain structure; hysteresis
77.22.Ej Polarization and depolarization
62.65.+k Acoustical properties of solids

Low-loss crystal-ion-sliced single-crystal potassium tantalate films

T. Izuhara, R. M. Osgood, M. Levy, M. E. Reeves, Y. G. Wang, A. N. Roy, and H. Bakhru

Appl. Phys. Lett. 80, 1046 (2002); http://dx.doi.org/10.1063/1.1446214 (3 pages) | Cited 8 times

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The dielectric response has been studied in 10-μm-thick, single-crystal potassium tantalate films formed by crystal ion slicing. Scanning microwave microscopy shows that the implanted, pre-etched samples exhibit a bulk-like permittivity and low-loss tangent (0.0009) at 1.7 GHz. The separated free-standing films have somewhat higher loss tangents due to residual-ion-induced stress. Selective relaxation of this stress by etching or annealing reduces the dielectric loss. © 2002 American Institute of Physics.
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77.55.-g Dielectric thin films
77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates
77.22.Ch Permittivity (dielectric function)
77.22.Gm Dielectric loss and relaxation
61.72.Cc Kinetics of defect formation and annealing
81.65.Cf Surface cleaning, etching, patterning

Stability of pinning centers in fatigued lead–zirconate–titanate

Jürgen Nuffer, Doru C. Lupascu, and Jürgen Rödel

Appl. Phys. Lett. 80, 1049 (2002); http://dx.doi.org/10.1063/1.1448654 (3 pages) | Cited 19 times

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After bipolar electric fatigue of bulk lead–zirconate–titanate ceramics, the well known reduced remnant polarization values are observed as well as an asymmetric strain hysteresis reflecting a macroscopic offset polarization. Thermal treatment and high electric fields each liberate the domain system from the microscopic defects responsible for the macroscopic offsets. High electric fields (4 Ec) only allow one to remove the type of pinning center inducing an offset polarization, while thermal treatment also removes more stable agglomerates and rejuvenates the material to almost its original properties. © 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.Ej Polarization and depolarization
77.80.Dj Domain structure; hysteresis
81.40.Gh Other heat and thermomechanical treatments

Tuning the electrical properties of zirconium oxide thin films

Byeong-Ok Cho, Jianjun Wang, Lin Sha, and Jane P. Chang

Appl. Phys. Lett. 80, 1052 (2002); http://dx.doi.org/10.1063/1.1448667 (3 pages) | Cited 39 times

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ZrO2 films obtained using plasma-enhanced chemical-vapor deposition exhibit various electrical properties tuned by the flow rate ratio of O2 to precursor-carrying Ar (O2/Ar), which controls the hydrocarbon incorporation in the films and the interfacial layer formation. As-deposited ZrO2 films obtained in oxygen-rich plasmas (O2/Ar ≥ 1) showed good electrical properties, including an overall dielectric constant of 16, a flatband voltage shift of −24 mV, an interfacial trap density of ∼ 1011 cm−2 eV−1, and a leakage current density of 3.3×10−6 A/cm2 at an equivalent oxide thickness of 25 Å, suitable for metal–oxide–semiconductor device applications. © 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
77.22.Ch Permittivity (dielectric function)
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
73.61.Ng Insulators
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