APL Nameplate
  • Volume/Page
  • Keyword
  • DOI
  • Citation
  • Advanced
   
 
 
 

Flickr Twitter iResearch App Facebook

BROWSE VOLUMES

Year Range: 
Search Issue | RSS Feeds RSS
Previous Issue Next Issue

7 Oct 2002

Volume 81, Issue 15, pp. 2677-2902

Page 2 of 4 Pages Previous Page Next Page | Jump to Page
back to top
RSS Feeds

Thermodynamic equilibrium and metal-organic interface dipole

Li Yan, N. J. Watkins, S. Zorba, Yongli Gao, and C. W. Tang

Appl. Phys. Lett. 81, 2752 (2002); http://dx.doi.org/10.1063/1.1512826 (3 pages) | Cited 39 times

Online Publication Date: 30 September 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We determined the interface dipoles at a number of metal-organic interfaces using ultraviolet and x-ray photoelectron spectroscopy. A linear dependence of the dipole on the metal work function is observed. This is consistent with the theory based on the charge transfer and thermodynamic equilibrium across the interface. The agreement suggests that charge transfer is one major factor in the formation of interface dipole. In addition, we find that the pushing back of the electron cloud tail that extends out of the metal surface and the permanent dipole moment of the organic molecule affect the interface dipole. © 2002 American Institute of Physics.
Show PACS
73.40.Ns Metal-nonmetal contacts
73.30.+y Surface double layers, Schottky barriers, and work functions
79.60.Jv Interfaces; heterostructures; nanostructures
73.20.-r Electron states at surfaces and interfaces
73.61.Ph Polymers; organic compounds

Near-band-edge photoluminescence of wurtzite-type AlN

E. Kuokstis, J. Zhang, Q. Fareed, J. W. Yang, G. Simin, M. Asif Khan, R. Gaska, M. Shur, C. Rojo, and L. Schowalter

Appl. Phys. Lett. 81, 2755 (2002); http://dx.doi.org/10.1063/1.1510586 (3 pages) | Cited 38 times

Online Publication Date: 30 September 2002

Full Text: Read Online (HTML) | Download PDF


See Also: Erratum

Show Abstract
Temperature-dependent photoluminescence (PL) measurements were performed for A-plane and C-plane bulk AlN single crystals and epitaxial layers on sapphire. A strong near-band-edge (NBE) emission and deep-level luminescence were observed. At low excitations, the emission spectra are dominated by free and bound excitonic transitions and their LO-phonon replicas. At high excitations, the broadening and redshift of the NBE band is attributed to dense electron–hole plasma formation. The PL spectra differences of bulk single crystals and epilayers is explained by the electron–hole plasma expansion peculiarities. © 2002 American Institute of Physics.
Show PACS
78.55.Cr III-V semiconductors
78.66.Fd III-V semiconductors
71.20.Nr Semiconductor compounds
71.35.Ee Electron-hole drops and electron-hole plasma
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping

Minimizing threading dislocations by redirection during cantilever epitaxial growth of GaN

D. M. Follstaedt, P. P. Provencio, N. A. Missert, C. C. Mitchell, D. D. Koleske, A. A. Allerman, and C. I. H. Ashby

Appl. Phys. Lett. 81, 2758 (2002); http://dx.doi.org/10.1063/1.1511286 (3 pages) | Cited 14 times

Online Publication Date: 30 September 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A 40-fold reduction in density of vertical threading dislocations (VTDs) at the surface of GaN is obtained with cantilever epitaxy by using narrow (<1 μm) mesas etched into a sapphire substrate and conditions producing angled {11-22} facets to initiate growth by metalorganic chemical vapor deposition. These two techniques redirect VTDs over the mesas to the horizontal and away from device areas above. Further reductions appear possible if the facets uniformly cover all mesas prior to cantilever growth. © 2002 American Institute of Physics.
Show PACS
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
81.05.Ea III-V semiconductors
61.72.Ff Direct observation of dislocations and other defects (etch pits, decoration, electron microscopy, x-ray topography, etc.)

Violet-blue photoluminescent properties of mesoporous zirconia modified with phosphoric acid

Hang-Rong Chen, Jian-Lin Shi, Yong Yang, Yong-Sheng Li, Dong-Sheng Yan, and Chao-Shu Shi

Appl. Phys. Lett. 81, 2761 (2002); http://dx.doi.org/10.1063/1.1512825 (3 pages) | Cited 8 times

Online Publication Date: 30 September 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Two strong violet-blue luminescence emissions at 390 and 440 nm under excitation at room temperature have been observed in the ordered mesoporous zirconium oxide post-treated with phosphoric acid. The oxide was characterized by powder x-ray diffraction, nitrogen adsorption, diffuse reflectance UV-vis spectroscopy, x-ray fluorescence analysis, and time-resolved photoluminescence decay spectra. It is concluded that these photoluminescence responses are related to the presence of P–O–Zr lumophores in tetrapodal framework due to the post-treatment with phosphoric acid, and are also related to the defects of oxygen vacancies in the mesoporous zirconia itself. The significant optical properties of this material may be very interesting for further application. © 2002 American Institute of Physics.
Show PACS
78.55.Mb Porous materials
81.05.Rm Porous materials; granular materials
78.47.-p Spectroscopy of solid state dynamics
78.40.Ha Other nonmetallic inorganics
68.43.Mn Adsorption kinetics
61.72.J- Point defects and defect clusters

Structural, dielectric, and magnetic properties of epitaxially grown BaFeO3 thin films on (100) SrTiO3 single-crystal substrates

T. Matsui, H. Tanaka, N. Fujimura, T. Ito, H. Mabuchi, and K. Morii

Appl. Phys. Lett. 81, 2764 (2002); http://dx.doi.org/10.1063/1.1513213 (3 pages) | Cited 27 times

Online Publication Date: 30 September 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We have prepared single-crystalline films of BaFeO3, which may contain high valent Fe4+ ions, on (100) SrTiO3 substrates by pulsed laser-beam deposition. The reflection high-energy electron diffraction patterns for the films apparently show a C4 symmetry operation, suggesting that the sample had a pseudocubic perovskite structure rather than hexagonal unit cell. The films were found to be highly insulating, and showed a high value of dielectric constant of ε = 59. At 300 K, the magnetization loop of the film apparently shows hysteresis, as well as small remanent magnetization. These characteristics are totally different from those of bulk BaFeO3. © 2002 American Institute of Physics.
Show PACS
68.55.-a Thin film structure and morphology
75.70.Ak Magnetic properties of monolayers and thin films
77.55.-g Dielectric thin films
81.15.Fg Pulsed laser ablation deposition
68.55.A- Nucleation and growth
77.80.-e Ferroelectricity and antiferroelectricity
77.84.Bw Elements, oxides, nitrides, borides, carbides, chalcogenides, etc.
77.22.Ch Permittivity (dielectric function)
75.50.Dd Nonmetallic ferromagnetic materials
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects

Impurity incorporation in InGaN grown by rf plasma-assisted molecular beam epitaxy

C. Poblenz, T. Mates, M. Craven, S. P. DenBaars, and J. S. Speck

Appl. Phys. Lett. 81, 2767 (2002); http://dx.doi.org/10.1063/1.1512817 (3 pages) | Cited 7 times

Online Publication Date: 30 September 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Impurity incorporation into InGaN films grown by rf-plasma assisted molecular beam epitaxy was investigated using secondary ion mass spectroscopy. A factor of 3 increase in both oxygen and boron incorporation into InGaN films relative to GaN films at 600 °C was demonstrated, and a factor of 10 increase in oxygen relative to the detectable base line in GaN grown under optimal conditions. Oxygen incorporation is related specifically to the different structures of the gallium and indium wetting layers on the growth surface. It is also shown using secondary ion mass spectroscopy that the formation of the gallium wetting layer during GaN growth is disrupted by the presence of excess indium; increased oxygen incorporation was observed during growth with an incomplete gallium wetting layer and indium on the growth surface. This study demonstrates the profound impact of surface atomic structure on impurity incorporation and reveals the protective nature of the gallium wetting layer as compared to the indium wetting layer during growth by rf-plasma assisted molecular beam epitaxy. © 2002 American Institute of Physics.
Show PACS
81.05.Ea III-V semiconductors
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
61.72.S- Impurities in crystals
52.77.Dq Plasma-based ion implantation and deposition
82.80.Ms Mass spectrometry (including SIMS, multiphoton ionization and resonance ionization mass spectrometry, MALDI)
68.35.B- Structure of clean surfaces (and surface reconstruction)

Si(100) surface morphology evolution during normal-incidence sputtering with 100–500 eV Ar+ ions

F. Ludwig, C. R. Eddy, O. Malis, and R. L. Headrick

Appl. Phys. Lett. 81, 2770 (2002); http://dx.doi.org/10.1063/1.1513655 (3 pages) | Cited 26 times

Online Publication Date: 30 September 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Grazing incidence small-angle x-ray scattering and atomic force microscopy have been used to systematically investigate the evolution of Si(100) surface morphology during normal-incidence Ar+ sputtering as a function of ion energy in the range of 100–500 eV. For ion energy ranges of 100–300 eV, two structures with distinct individual length scales and behaviors form on the surface. There is a smaller scale (lateral size of 20–50 nm) morphology that grows in scattering intensity and coarsens with time. There is also a larger scale (lateral size of approximately 100 nm) morphology that grows in scattering intensity but does not coarsen significantly in the time scales studied. At higher energies (400–500 eV), sputtering causes the Si(100) surface to become smoother on length scales smaller than 200 nm. © 2002 American Institute of Physics.
Show PACS
68.35.B- Structure of clean surfaces (and surface reconstruction)
68.49.Sf Ion scattering from surfaces (charge transfer, sputtering, SIMS)
79.20.Rf Atomic, molecular, and ion beam impact and interactions with surfaces
68.37.Ps Atomic force microscopy (AFM)
61.05.cf X-ray scattering (including small-angle scattering)

Effect of Si doping on the relaxation mechanism of InGaAs on GaAs

P. J. Parbrook, B. K. Tanner, B. Lunn, J. H. C. Hogg, A. M. Keir, and A. D. Johnson

Appl. Phys. Lett. 81, 2773 (2002); http://dx.doi.org/10.1063/1.1513181 (3 pages) | Cited 3 times

Online Publication Date: 30 September 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report measurements on the initial stages of relaxation of Si-doped In0.04Ga0.96As epitaxial layers on (001) GaAs using in situ high-resolution double-crystal x-ray topography during molecular beam epitaxial growth. For Si concentrations up to 5×1018 cm−3, the critical thickness for formation of the first B(g) misfit dislocations is modeled accurately by the Matthews–Blakeslee model, extended to include a lattice friction force varying linearly with the dopant concentration. Below a Si concentration of 2×1018 cm−3, the model can be used to predict the critical thickness for generation of the orthogonal A(g) dislocation set, with the x-ray topographs showing that the B(g) misfit multiplication occurs at damaged edges of the wafer. However, above 2×1018 cm−3 Si concentration, the critical thickness for A(g) nucleation becomes almost independent of concentration and the x-ray topographs show that cross slip becomes important in the multiplication process. For most of the Si concentrations examined, the critical thickness for nucleation of the slow A(g) misfit dislocations corresponded to that of multiplication of the fast B(g) set. © 2002 American Institute of Physics.
Show PACS
61.72.Ff Direct observation of dislocations and other defects (etch pits, decoration, electron microscopy, x-ray topography, etc.)
61.72.Lk Linear defects: dislocations, disclinations
68.55.-a Thin film structure and morphology
61.72.Bb Theories and models of crystal defects

Structural study of a commensurate phase at Co/Si(111) interface using in situ surface x-ray scattering

T. S. Kang, J. H. Je, H. J. Kim, D. Y. Noh, N. D. Kim, and J. W. Chung

Appl. Phys. Lett. 81, 2776 (2002); http://dx.doi.org/10.1063/1.1513658 (3 pages) | Cited 1 time

Online Publication Date: 30 September 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Interfacial structure and reaction stoichiometry of the Co-adsorbed Si(111) surface at room temperature has been studied by in situ synchrotron surface x-ray scattering. The intensity oscillation at the anti-Bragg position of the (1,0) off-specular crystal truncation rod indicates a layerwise consumption of silicon substrate during the deposition of the first 15 Co monolayers. Our data suggest that an interfacial silicide layer formed in the initial stage of growth have the atomic stoichiometry of Co2Si. The silicide layer is a commensurate phase of pseudohexagonal Co2Si, which shows a long-range order with large strain imposed by the Si substrate. © 2002 American Institute of Physics.
Show PACS
68.35.Ct Interface structure and roughness
68.35.Dv Composition, segregation; defects and impurities
78.70.Ck X-ray scattering
61.66.Bi Elemental solids
61.66.Dk Alloys
back to top
RSS Feeds

Control of the confining potential in ballistic constrictions using a persistent charging effect

S. F. Fischer, G. Apetrii, S. Skaberna, U. Kunze, D. Reuter, and A. D. Wieck

Appl. Phys. Lett. 81, 2779 (2002); http://dx.doi.org/10.1063/1.1511278 (3 pages) | Cited 9 times

Online Publication Date: 30 September 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
GaAs/AlGaAs quantum point contacts are fabricated by atomic force microscope lithography and wet chemical etching. The lateral confinement potential of a given ballistic constriction is varied by persistent fractional charging of the donors in the supply layer. A forward bias voltage applied to the gate electrode during sample cooling shifts the conductance threshold at T = 4.2 K towards higher gate voltage due to partial neutralization of the donors. Simultaneously, the width of the quantized conductance plateaus at multiples of 2e2/h decreases. Measurements under finite drain voltage reveal a reduction of the lowest subband separation from ΔE1,2 = 17.5±1 to 13±1 meV as the cooling bias voltage is raised from 0 to +0.6 V. © 2002 American Institute of Physics.
Show PACS
73.63.Rt Nanoscale contacts
73.23.Ad Ballistic transport
73.23.Ra Persistent currents
81.07.Lk Nanocontacts
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems

Band bending mechanism for field emission in wide-band gap semiconductors

R. Z. Wang, B. Wang, H. Wang, H. Zhou, A. P. Huang, M. K. Zhu, H. Yan, and X. H. Yan

Appl. Phys. Lett. 81, 2782 (2002); http://dx.doi.org/10.1063/1.1511809 (3 pages) | Cited 25 times

Online Publication Date: 30 September 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A theoretical model based on the band bending theory was developed for explaining the field-emission mechanism of wide-band gap semiconductors (WBGSs). It was shown that the maximum value of the band bending, which is nearly linearly proportional to the band gap of WBGSs, may amount to a few eV. Furthermore, the calculated field-emission energy distribution combined with the band bending analyzed on cubic boron nitride (c-BN) as typical one of WBGSs, indicated that the electron emission originates from the conduction band minimum resulting from the band bending. These results present a perspective to explain the field-emission mechanism, in which it is considered that the band bending, as well as the negative electron affinity, is of equal importance to the excellent field emission performances of WBGSs. © 2002 American Institute of Physics.
Show PACS
79.70.+q Field emission, ionization, evaporation, and desorption
71.20.Nr Semiconductor compounds
81.05.Ea III-V semiconductors

Thermal and doping dependence of 4H-SiC polytype transformation

L. J. Brillson, S. Tumakha, G. H. Jessen, R. S. Okojie, M. Zhang, and P. Pirouz

Appl. Phys. Lett. 81, 2785 (2002); http://dx.doi.org/10.1063/1.1512816 (3 pages) | Cited 19 times

Online Publication Date: 30 September 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We have observed characteristic temperatures, anneal times, and doping densities that lead to stacking faults and 3C-SiC-like bands in 4H-SiC epilayers. Low energy cathodoluminescence spectroscopy measurements reveal a temperature threshold of 800 °C for emergence of these features in thermally oxidized or argon annealed 4H-SiC with an activation energy ≈2.5 eV. Stacking fault generation and polytype transformation exhibits a strong doping dependence, appearing only in a range of highly doped n-type 4H-SiC. Systematics of these strain and/or electronic effects induced by high N concentrations can be used to control structural instabilities during SiC device fabrication. © 2002 American Institute of Physics.
Show PACS
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
64.70.K- Solid-solid transitions
78.60.Hk Cathodoluminescence, ionoluminescence
61.72.Cc Kinetics of defect formation and annealing
78.66.Li Other semiconductors
61.72.up Other materials
61.72.Nn Stacking faults and other planar or extended defects
81.65.Mq Oxidation

Relaxation of photoinjected spins during drift transport in GaAs

H. Sanada, I. Arata, Y. Ohno, Z. Chen, K. Kayanuma, Y. Oka, F. Matsukura, and H. Ohno

Appl. Phys. Lett. 81, 2788 (2002); http://dx.doi.org/10.1063/1.1512818 (3 pages) | Cited 34 times

Online Publication Date: 30 September 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We studied the transport of photoinjected spins in GaAs by time-resolved photoluminescence measurements. At low temperatures, the spin polarization after drift transport of 4 μm is found to decrease as the applied electric field E increases to a few kV/cm, and it disappears when E exceeds 3 kV/cm. The origin of the field-dependent spin relaxation is discussed. © 2002 American Institute of Physics.
Show PACS
72.25.Dc Spin polarized transport in semiconductors
72.25.Rb Spin relaxation and scattering
78.47.-p Spectroscopy of solid state dynamics
78.55.Cr III-V semiconductors

Coherent generation of 100 GHz acoustic phonons by dynamic screening of piezoelectric fields in AlGaN/GaN multilayers

E. Makarona, B. Daly, J.-S. Im, H. Maris, A. Nurmikko, and Jung Han

Appl. Phys. Lett. 81, 2791 (2002); http://dx.doi.org/10.1063/1.1512821 (3 pages) | Cited 14 times

Online Publication Date: 30 September 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Ultrashort pulse laser techniques have been used to observe and characterize the generation of coherent phonons by rapid screening of strain-induced piezoelectric polarization fields in AlGaN/GaN multilayers. The results are compared with those where coherent phonons are launched by optical techniques without the carrier injections process to show consistency with the anticipated longitudinal phonon dispersion in the nitride semiconductor samples. © 2002 American Institute of Physics.
Show PACS
63.22.-m Phonons or vibrational states in low-dimensional structures and nanoscale materials
77.65.Ly Strain-induced piezoelectric fields
78.20.hb Piezo-optical, elasto-optical, acousto-optical, and photoelastic effects
63.20.D- Phonon states and bands, normal modes, and phonon dispersion
77.84.Bw Elements, oxides, nitrides, borides, carbides, chalcogenides, etc.
78.67.-n Optical properties of low-dimensional, mesoscopic, and nanoscale materials and structures
73.21.Ac Multilayers
43.35.Ud Thermoacoustics, high temperature acoustics, photoacoustic effect

Energy relaxation during hot-exciton transport in quantum wells: Direct observation by spatially resolved phonon-sideband spectroscopy

Hui Zhao, Sebastian Moehl, and Heinz Kalt

Appl. Phys. Lett. 81, 2794 (2002); http://dx.doi.org/10.1063/1.1512819 (3 pages) | Cited 10 times

Online Publication Date: 30 September 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We investigate the energy relaxation of excitons during the real-space transport in ZnSe quantum wells by using microphotoluminescence with spatial resolution enhanced by a solid immersion lens. The spatial evolution of the LO-phonon sideband, originating from the LO-phonon assisted recombination of hot excitons, is measured directly. By calculating the LO-phonon assisted recombination probability, we obtain the nonthermal energy distribution of excitons and observe directly the energy relaxation of hot excitons during their transport. We find the excitons remain hot during their transport on a length scale of several micrometers. Thus, the excitonic transport on this scale cannot be described by classical diffusion. © 2002 American Institute of Physics.
Show PACS
73.21.Fg Quantum wells
71.35.Gg Exciton-mediated interactions
78.67.De Quantum wells
63.20.kk Phonon interactions with other quasiparticles
78.55.Et II-VI semiconductors
63.22.-m Phonons or vibrational states in low-dimensional structures and nanoscale materials

Analysis of piezoresistance in n-type β-SiC for high-temperature mechanical sensors

Toshiyuki Toriyama and Susumu Sugiyama

Appl. Phys. Lett. 81, 2797 (2002); http://dx.doi.org/10.1063/1.1513652 (3 pages) | Cited 12 times

Online Publication Date: 30 September 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Piezoresistance in n-type β-SiC was analyzed on the basis of electron transfer and mobility shift mechanisms for cubic many-valley semiconductors. Gauge factors were calculated by using shear deformation potential constant Ξu. The calculation was compared with experimental results taken from the literature. It was shown that incorporation of the electron transfer and the mobility shift mechanisms gives reasonable interpretation for piezoresistance in n-type β-SiC within the temperature range from 300 to 673 K, and impurity concentration range from 1018 to 1020 cm−3. These conditions correspond to typical operation ranges of high-temperature piezoresistive sensors. The effect of the intervalley scattering on piezoresistance can be neglected from the evidence that gauge factor is inversely proportional to temperature within the abovementioned conditions. © 2002 American Institute of Physics.
Show PACS
85.50.-n Dielectric, ferroelectric, and piezoelectric devices
72.20.Fr Low-field transport and mobility; piezoresistance
43.38.Fx Piezoelectric and ferroelectric transducers
85.85.+j Micro- and nano-electromechanical systems (MEMS/NEMS) and devices
84.32.Ff Conductors, resistors (including thermistors, varistors, and photoresistors)
07.07.Df Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing
07.10.Cm Micromechanical devices and systems

Local electronic structures of GaMnAs observed by cross-sectional scanning tunneling microscopy

T. Tsuruoka, N. Tachikawa, S. Ushioda, F. Matsukura, K. Takamura, and H. Ohno

Appl. Phys. Lett. 81, 2800 (2002); http://dx.doi.org/10.1063/1.1512953 (3 pages) | Cited 22 times

Online Publication Date: 30 September 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Using cross-sectional scanning tunneling microscopy (STM), we have investigated the local electronic properties of molecular-beam epitaxy grown GaMnAs layers on a p-GaAs substrate. The STM image shows light and dark areas with the average size on the order of nm. From conductance spectra measured with the STM, the bandgap of the GaMnAs is estimated to be 1.23±0.05 eV. An apparent conductance within the bandgap indicates the presence of hole states in the valence band, which are induced by Mn acceptors. A conductance peak at 0.7 eV above the valence band edge can be identified with electron tunneling into the ionization levels of As antisites. © 2002 American Institute of Physics.
Show PACS
71.20.Nr Semiconductor compounds
75.50.Pp Magnetic semiconductors
71.55.Eq III-V semiconductors
73.61.Ey III-V semiconductors
61.72.J- Point defects and defect clusters
68.37.Ef Scanning tunneling microscopy (including chemistry induced with STM)
back to top
RSS Feeds

Flux pinning and critical currents at low-angle grain boundaries in high-temperature superconductors

D. Agassi, D. K. Christen, and S. J. Pennycook

Appl. Phys. Lett. 81, 2803 (2002); http://dx.doi.org/10.1063/1.1502907 (3 pages) | Cited 9 times

Online Publication Date: 30 September 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Calculations of the pinning potential at low-angle grain boundaries in high-temperature superconductors are presented which fully incorporate the periodic nature of the low-angle boundary. A nonlocal kernel provides a smooth transition from an Abrikosov vortex far from the boundary to a Josephson vortex near the dislocations. We examine the angular dependence of critical current in the two idealized limits of pure strain and pure band bending. Recent data appear limited by band bending with significant potential for improvement through doping. © 2002 American Institute of Physics.
Show PACS
74.25.Uv Vortex phases (includes vortex lattices, vortex liquids, and vortex glasses)
74.25.Sv Critical currents
61.72.Mm Grain and twin boundaries
74.72.-h Cuprate superconductors

Magnetization reversal in GaMnAs layers studied by Kerr effect

D. Hrabovsky, E. Vanelle, A. R. Fert, D. S. Yee, J. P. Redoules, J. Sadowski, J. Kanski, and L. Ilver

Appl. Phys. Lett. 81, 2806 (2002); http://dx.doi.org/10.1063/1.1506204 (3 pages) | Cited 40 times

Online Publication Date: 30 September 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
In this letter, magnetization reversal is investigated in (Ga,Mn)As thin films using the magneto-optical Kerr effect. A Stoner–Wohlfart model, modified to take into account the existence of magnetic reversal discontinuities associated with nucleation and propagation phenomena allows us to estimate most of the characteristic constants. These results demonstrate a reversal behavior analogous to that observed in metallic magnetic layers (coherent rotation followed by a nucleation propagation process). The dynamic study at T = 20 K shows a strong increase of the coercivity with the increase of dH/dt. This effect is related to the random distribution of Mn magnetic ions in the lattice. © 2002 American Institute of Physics.
Show PACS
75.60.Jk Magnetization reversal mechanisms
75.50.Pp Magnetic semiconductors
75.70.Ak Magnetic properties of monolayers and thin films
78.20.Ls Magneto-optical effects
78.66.Fd III-V semiconductors
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
75.20.Hr Local moment in compounds and alloys; Kondo effect, valence fluctuations, heavy fermions

Giant magnetoresistance in 60–150-nm-wide pseudo-spin-valve nanowires

F. J. Castaño, S. Haratani, Y. Hao, C. A. Ross, and Henry I. Smith

Appl. Phys. Lett. 81, 2809 (2002); http://dx.doi.org/10.1063/1.1512327 (3 pages) | Cited 14 times

Online Publication Date: 30 September 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The magnetic and magnetotransport properties exhibited by arrays of 60–150-nm-wide pseudo-spin-valve (PSV) nanowires have been investigated. The starting PSV thin film consisted of sputtered NiFe (6 nm)/Cu(3.7 nm)/Co(3 nm)/Cu(3 nm), exhibiting a room temperature giant magnetoresistance (GMR) ratio of 2.5%. Large area arrays of 150-, 80-, and 60-nm-wide nanowires were patterned from this PSV film using a combination of interference lithography and ion milling. The effects of reducing the width of the wires are a monotonic decrease in the GMR ratio and the saturation magnetization, and an increase of both the resistivity of the wires and the average switching fields of the magnetic layers. On cooling the samples to 77 K, the resistivity decreases slightly and the GMR amplitude increases independently of the width of the wires. These results suggest the presence of a disordered region at the edges of the wires as a result of processing, which increases the resistivity and decreases the saturation magnetization as the wire width decreases. © 2002 American Institute of Physics.
Show PACS
75.47.De Giant magnetoresistance
75.70.Cn Magnetic properties of interfaces (multilayers, superlattices, heterostructures)
73.63.Nm Quantum wires
75.75.-c Magnetic properties of nanostructures
81.07.Vb Quantum wires
72.15.Gd Galvanomagnetic and other magnetotransport effects
72.25.Mk Spin transport through interfaces
73.50.Jt Galvanomagnetic and other magnetotransport effects (including thermomagnetic effects)
75.50.Cc Other ferromagnetic metals and alloys
75.50.Bb Fe and its alloys
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
81.05.Bx Metals, semimetals, and alloys
85.75.-d Magnetoelectronics; spintronics: devices exploiting spin polarized transport or integrated magnetic fields
85.70.Kh Magnetic thin film devices: magnetic heads (magnetoresistive, inductive, etc.); domain-motion devices, etc.

Atomic disorder in Heusler Co2MnGe measured by anomalous x-ray diffraction

B. Ravel, J. O. Cross, M. P. Raphael, V. G. Harris, R. Ramesh, and L. V. Saraf

Appl. Phys. Lett. 81, 2812 (2002); http://dx.doi.org/10.1063/1.1513216 (3 pages) | Cited 42 times

Online Publication Date: 30 September 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Heusler alloys Co2MnX, where X is Ge or Si, are predicted by the band theory to be a half-metallic ferromagnets, i.e., metals with all conduction electrons of the same spin state. To date, Heusler alloys have been measured with spin polarizations of 50%–60%, higher than Fe (∼40%), but not a true half metal. Structural defects involving site swapping between the Co and Mn sublattices have been proposed as a mechanism to diminish spin polarization. In this work, we present an anomalous x-ray diffraction measurement on Co2MnGe to determine antisite disorder in thin films with a high precision. © 2002 American Institute of Physics.
Show PACS
68.55.-a Thin film structure and morphology
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
75.50.Cc Other ferromagnetic metals and alloys
61.72.J- Point defects and defect clusters
75.70.Ak Magnetic properties of monolayers and thin films

Signal decay and amplitude measurements of antiferromagnetically coupled magnetic recording media

Andreas Moser, David T. Margulies, Charles T. Rettner, and Eric E. Fullerton

Appl. Phys. Lett. 81, 2815 (2002); http://dx.doi.org/10.1063/1.1512958 (3 pages) | Cited 2 times

Online Publication Date: 30 September 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Using a conventional spin stand we have investigated the recording and decay processes of antiferromagnetically coupled (AFC) longitudinal magnetic media. For AFC media with thick lower layers, both the signal amplitude and decay oscillate when measured as a function of transition density. Using heads with different write-pole geometries, we find that the oscillation frequency scales with the thickness of the write pole, from which we conclude that the magnetic field at the trailing edge of the write head is sufficiently large to write transitions into the lower layer of the AFC media. © 2002 American Institute of Physics.
Show PACS
75.50.Ss Magnetic recording materials

Superhigh strains by variant reorientation in the nonmodulated ferromagnetic NiMnGa alloys

Chengbao Jiang, Ting Liang, Huibin Xu, Ming Zhang, and Guangheng Wu

Appl. Phys. Lett. 81, 2818 (2002); http://dx.doi.org/10.1063/1.1512948 (3 pages) | Cited 40 times

Online Publication Date: 30 September 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Superhigh strains of 15% for the Ni53Mn25Ga22 and 13.5% for the Ni54Mn23Ga23 with the nonmodulated martensite structure were achieved by variant reorientation. A strong magnetic anisotropy exists in the prefabricated single variant with the easy axis along the contraction [001] direction of the high-temperature cubic phase. A higher austenitic transformation temperature was found in the single variant comparing with the original multivariant sample. The same order of magnitude for the saturation magnetization Ms, magnetic anisotropy constant ku, and the twin reorientation stress σtw, namely, 57.6 A m2/kg, 1.4×105 J/m3, and approximately 20 MPa, respectively, as those in 5M martensite indicate that it is reasonable to expect a much higher magnetic field-induced-strain in the nonmodulated NiMnGa alloys. © 2002 American Institute of Physics.
Show PACS
75.80.+q Magnetomechanical effects, magnetostriction
75.50.Cc Other ferromagnetic metals and alloys
75.30.Gw Magnetic anisotropy
81.30.Kf Martensitic transformations
64.70.K- Solid-solid transitions
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
back to top
RSS Feeds

Energy band structure of Ru/(Ba,Sr)TiO3/Si capacitor deposited by inductively-coupled plasma-assisted radio-frequency-magnetron plasma sputtering

Takamaro Kikkawa, Naonori Fujiwara, Hiroshi Yamada, Seiichi Miyazaki, Fumitaka Nishiyama, and Masataka Hirose

Appl. Phys. Lett. 81, 2821 (2002); http://dx.doi.org/10.1063/1.1509467 (3 pages) | Cited 8 times

Online Publication Date: 30 September 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Properties of barium strontium titanate (Ba,Sr)TiO3 (BST) thin films, deposited by inductively-coupled-plasma (ICP)-assisted rf magnetron-plasma sputtering, were investigated. It is found that the ICP-assisted rf-magnetron plasma improved the stoichiometry of the BST film. The energy band structure of the Ru/BST/Si system was investigated. It is found that the bandgaps of BST and interface SiO2 were 4.30 and 8.95 eV, respectively, and the work function of Ru was 4.97 eV. The valence band offsets for BST/Si and interface SiO2/Si are 3.55 and 4.48 eV, respectively. As a result, the conduction band barrier height of Ru against BST was found to be 1.40 eV. © 2002 American Institute of Physics.
Show PACS
84.32.Tt Capacitors
73.40.Qv Metal-insulator-semiconductor structures (including semiconductor-to-insulator)
73.30.+y Surface double layers, Schottky barriers, and work functions
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems

Atomic-layer deposition of ZrO2 with a Si nitride barrier layer

Anri Nakajima, Toshirou Kidera, Hiroyuki Ishii, and Shin Yokoyama

Appl. Phys. Lett. 81, 2824 (2002); http://dx.doi.org/10.1063/1.1510584 (3 pages) | Cited 21 times

Online Publication Date: 30 September 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
ZrO2 thin films for gate dielectrics have been formed at low temperatures (200 °C) by an atomic-layer deposition (ALD) technique using Zr(t-OC4H9)4 and H2O source gases. An ultrathin (physical thickness Tphy of ∼0.5 nm) Si nitride layer was deposited on a Si substrate by ALD before the deposition of ZrO2. Transmission electron microscopy showed that the Si nitride barrier layer successfully suppressed the formation of a SiO2 interfacial layer. Because of the extremely uniform thickness control capability in the ultrathin region and the low thermal budget of the ALD process, the ALD process for the ZrO2/Si nitride stack structure is a promising candidate for fabricating the ultrathin gate dielectrics for sub-0.1-μm complementary metal–oxide–semiconductor transistors. © 2002 American Institute of Physics.
Show PACS
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
85.40.Sz Deposition technology
68.37.Lp Transmission electron microscopy (TEM)
Page 2 of 4 Pages Previous Page Next Page | Jump to Page
Close

Google Calendar

ADVERTISEMENT

Go to AIP Home   © AIP Publishing LLC
close