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

13 Oct 2003

Volume 83, Issue 15, pp. 2991-3216

Issue Cover Spotlight Figure

Appl. Phys. Lett. 83, 3159 (2003); http://dx.doi.org/10.1063/1.1617378 (3 pages)

Zheng Wei Pan, Sheng Dai, David B. Beach, and Douglas H. Lowndes
Enlarge Image | Read More
Page 2 of 4 Pages Previous Page Next Page | Jump to Page
back to top
RSS Feeds

Effects of copolymer segment length and reversible deformation on the molecular surface structure of polyurethane

E. Amitay-Sadovsky, K. Komvopoulos, R. Ward, and G. A. Somorjai

Appl. Phys. Lett. 83, 3066 (2003); http://dx.doi.org/10.1063/1.1610249 (3 pages) | Cited 3 times

Online Publication Date: 7 October 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The surface molecular structure and the deformation mechanisms of two polyurethane (PUR) short-segmented copolymers were studied by sum frequency generation (SFG) vibrational spectroscopy. These PURs differ only in the length of their hard segment. Surface deformation was induced by cyclically stretching the PUR films to a macroscopic elastic elongation. Results for both PUR compositions indicate that the upward orientation of the methylene groups increases with elongation and decreases upon relaxation. The surface of the stretched PUR films with shorter hard segments exhibited irreversible deformation at the molecular level. This produced a surface composition similar to that of PUR with longer hard segments that deformed only elastically after three stretching cycles. This behavior indicates that the surface structure of PUR copolymers can be controlled by mechanical manipulation or by modification of the copolymer segment length. © 2003 American Institute of Physics.
Show PACS
68.35.B- Structure of clean surfaces (and surface reconstruction)
61.41.+e Polymers, elastomers, and plastics
62.20.F- Deformation and plasticity
81.40.Lm Deformation, plasticity, and creep
81.05.Lg Polymers and plastics; rubber; synthetic and natural fibers; organometallic and organic materials

Strain relaxation in stacked InAs/GaAs quantum dots studied by Raman scattering

J. Ibáñez, A. Patanè, M. Henini, L. Eaves, S. Hernández, R. Cuscó, L. Artús, Yu. G. Musikhin, and P. N. Brounkov

Appl. Phys. Lett. 83, 3069 (2003); http://dx.doi.org/10.1063/1.1618368 (3 pages) | Cited 17 times

Online Publication Date: 7 October 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report a Raman scattering investigation of InAs vibrational modes in multiple layers of InAs self-assembled quantum dots in a GaAs matrix. The Raman peak associated with quantum-dot phonons shows a downward frequency shift as the interlayer spacing decreases. We attribute this frequency shift to the relaxation of the elastic strain in the stacked quantum-dot layers. From the phonon frequency shift, we estimate the magnitude of the strain in the quantum dot layers, which we relate to the energy of the photoluminescence emission of the dots. © 2003 American Institute of Physics.
Show PACS
68.65.Hb Quantum dots (patterned in quantum wells)
78.67.Hc Quantum dots
78.30.Fs III-V and II-VI semiconductors
63.22.-m Phonons or vibrational states in low-dimensional structures and nanoscale materials
78.55.Cr III-V semiconductors

Growth and characteristics of TaN/TiN superlattice structures

H. Wang, X. Zhang, A. Gupta, Ashutosh Tiwari, and J. Narayan

Appl. Phys. Lett. 83, 3072 (2003); http://dx.doi.org/10.1063/1.1616656 (3 pages) | Cited 2 times

Online Publication Date: 7 October 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Epitaxial B1 NaCl-structured TaN(3 nm)/TiN(2 nm) superlattice structures were grown on Si(100) substrates with a TiN buffer layer, using pulsed-laser deposition. A special target assembly was used to manipulate the thickness of each layer. X-ray diffraction, transmission electron microscopy, and scanning transmission electron microscopy (Z contrast) studies confirmed the single-crystalline nature of the superlattice with a uniform layer structure. Nanoindentation results suggest the high hardness of these superlattice structures. Four-point-probe resistivity measurements show low resistivity of the heterostructures and a Cu diffusion characteristic study proved this superlattice system can be a promising diffusion barrier and can withstand 700 °C annealing for 30 min. © 2003 American Institute of Physics.
Show PACS
68.65.Cd Superlattices
81.15.Fg Pulsed laser ablation deposition
81.16.Mk Laser-assisted deposition
68.35.Gy Mechanical properties; surface strains
62.20.M- Structural failure of materials
62.20.Qp Friction, tribology, and hardness
81.40.Np Fatigue, corrosion fatigue, embrittlement, cracking, fracture, and failure
61.72.Cc Kinetics of defect formation and annealing
68.35.Fx Diffusion; interface formation
73.61.Ng Insulators

Experimental and theoretical investigation on the structural properties of GaN grown on sapphire

J. Ohta, H. Fujioka, M. Oshima, K. Fujiwara, and A. Ishii

Appl. Phys. Lett. 83, 3075 (2003); http://dx.doi.org/10.1063/1.1618379 (3 pages) | Cited 27 times

Online Publication Date: 7 October 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We have investigated the growth mechanisms of group-III nitrides on c-plane sapphire substrates with experiments by pulsed-laser deposition and first-principles calculations. It has been experimentally revealed that the in-plane alignment between the nitrides and sapphire is [10-10]nitride//[11-20]sapphire and the nitride films have the N polarity for the most cases. We have found that the insertion of an Al-rich AlN buffer layer effectively turns over the GaN crystals from the N polarity to the Ga polarity, although the Ga-rich GaN buffer layer does not cause change in the polarity. The theoretical energy calculations of a sapphire slab with an adatom explain the experimental results, such as the in-plane alignment and the polarity change, quite well. © 2003 American Institute of Physics.
Show PACS
68.55.-a Thin film structure and morphology
68.35.Md Surface thermodynamics, surface energies

Room-temperature preparation of β-FeSi2 microprecipitates by the KrF excimer laser ablation of an iron disilicide alloy target

Aiko Narazaki, Tadatake Sato, Yoshizo Kawaguchi, and Hiroyuki Niino

Appl. Phys. Lett. 83, 3078 (2003); http://dx.doi.org/10.1063/1.1618019 (3 pages) | Cited 4 times

Online Publication Date: 7 October 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We have fabricated β-FeSi2 microprecipitates at room temperature using KrF excimer laser ablation of an α-FeSi2 alloy target. Raman spectra with a spatial resolution of 1 μm confirmed that the micron-sized droplets generated by laser ablation precipitate as the β-FeSi2 crystalline phase on a silicon substrate maintained at RT, whereas the rest of the deposited film is amorphous. It was also found that films containing a high density of β-FeSi2 precipitates exhibited 1.55 μm photoluminescence at low temperature (up to 200 K) after annealing at 800 °C for 6 h in an argon atmosphere. © 2003 American Institute of Physics.
Show PACS
81.15.Fg Pulsed laser ablation deposition
68.55.-a Thin film structure and morphology
64.75.-g Phase equilibria
61.72.Cc Kinetics of defect formation and annealing
78.55.Hx Other solid inorganic materials
78.30.Hv Other nonmetallic inorganics
78.66.Li Other semiconductors

Ultrathin single-crystalline-silicon cantilever resonators: Fabrication technology and significant specimen size effect on Young’s modulus

Xinxin Li, Takahito Ono, Yuelin Wang, and Masayoshi Esashi

Appl. Phys. Lett. 83, 3081 (2003); http://dx.doi.org/10.1063/1.1618369 (3 pages) | Cited 115 times

Online Publication Date: 7 October 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Ultrathin resonant cantilevers are promising for ultrasensitive detection. A technique is developed for high-yield fabrication of single-crystalline-silicon cantilevers as thin as 12 nm. The formed cantilever resonators are characterized by resonance testing in high vacuum. Significant specimen size effect on Young’s modulus of ultrathin (12–170 nm) silicon is detected. The Young’s modulus decreases monotonously as the cantilevers become thinner. The size effect is consistent with the published simulation results of direct-atomistic model, in which surface effects are taken into consideration. © 2003 American Institute of Physics.
Show PACS
07.10.Cm Micromechanical devices and systems
85.85.+j Micro- and nano-electromechanical systems (MEMS/NEMS) and devices
81.05.Cy Elemental semiconductors
62.25.-g Mechanical properties of nanoscale systems
62.20.D- Elasticity
81.16.-c Methods of micro- and nanofabrication and processing
61.46.-w Structure of nanoscale materials
81.07.Bc Nanocrystalline materials

Room-temperature light emission from a highly strained Si/Ge superlattice

N. D. Zakharov, V. G. Talalaev, P. Werner, A. A. Tonkikh, and G. E. Cirlin

Appl. Phys. Lett. 83, 3084 (2003); http://dx.doi.org/10.1063/1.1618377 (3 pages) | Cited 25 times

Online Publication Date: 7 October 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We discuss the formation of a Si/Ge-superlattice (SL) generated by molecular beam epitaxy. Specific growth parameter were chosen to optimize the periodic structure of vertically stacked Ge islands. Optimized SLs show a strong photoluminescence at a wavelength in the region of 1.55 μm up to room temperature. The luminescence is explained by a recombination of electrons in a miniband and holes localized in the Ge islands. The morphology and the crystal structure of the SL, which are influenced by the growth parameters, were analyzed by transmission electron microscopy techniques. It is demonstrated that doping of the SL structure by antimony improves both structural and optical properties. © 2003 American Institute of Physics.
Show PACS
78.67.Pt Multilayers; superlattices; photonic structures; metamaterials
68.65.Cd Superlattices
78.55.Ap Elemental semiconductors
68.37.Lp Transmission electron microscopy (TEM)

Observation of huge nonlinear absorption enhancement near exciton resonance in GaN

Kung-Hsuan Lin, Gia-Wei Chern, Yin-Chieh Huang, Stacia Keller, Steven P. DenBaars, and Chi-Kuang Sun

Appl. Phys. Lett. 83, 3087 (2003); http://dx.doi.org/10.1063/1.1619218 (3 pages) | Cited 9 times

Online Publication Date: 7 October 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Huge excitonic enhancement of two-photon absorption near the exciton-transition energy was observed in the GaN system. The peak value of the nonlinear absorption coefficient is at least 1500 cm/GW, corresponding to an enhancement factor of >100. The room temperature exciton dephasing time is also obtained based on a spectral analysis to be ∼150 fs in bulk GaN, which is close to the exciton ionization time. © 2003 American Institute of Physics.
Show PACS
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
71.35.Cc Intrinsic properties of excitons; optical absorption spectra

Frequency converters from visible to mid-infrared with periodically poled RbTiOPO4

A. Fragemann, V. Pasiskevicius, J. Nordborg, J. Hellström, H. Karlsson, and F. Laurell

Appl. Phys. Lett. 83, 3090 (2003); http://dx.doi.org/10.1063/1.1619211 (3 pages) | Cited 3 times

Online Publication Date: 7 October 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Electric-field poling has been used to fabricate quasi-phase-matched frequency converters in RbTiOPO4. A more accurate Sellmeier equation has been obtained for wavelengths between 0.43 and 3.4 μm. The dispersion of the thermo-optic coefficient for nz refractive index has been derived in the near- to mid-infrared spectral region. The nonlinear performance of periodically poled RbTiOPO4 obtained in the infrared optical parametric devices is comparable to that of periodically poled KTiOPO4. © 2003 American Institute of Physics.
Show PACS
42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation
42.70.Nq Other nonlinear optical materials; photorefractive and semiconductor materials
78.20.N- Thermo-optic effects
78.20.nb Photothermal effects
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)

Role of nanometer-scale quasicrystals in improving the mechanical behavior of Ti-based bulk metallic glasses

Yu Chan Kim, Jong Hyun Na, Jin Man Park, Do Hyang Kim, Jin Kyu Lee, and Won Tae Kim

Appl. Phys. Lett. 83, 3093 (2003); http://dx.doi.org/10.1063/1.1616198 (3 pages) | Cited 73 times

Online Publication Date: 7 October 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The effect of the precipitation of nanosized quasicrystals on the mechanical properties of Ti–Zr–Cu–Ni–Be bulk metallic glasses (BMG) has been investigated. The Ti40Zr29Cu8Ni7Be16 BMG crystallizes by forming a few nanometer-size quasicrystals in the amorphous matrix, enabling the fabrication of quasicrystal-reinforced BMG matrix composites. Simultaneous improvement of strength and ductility can be obtained when 3–5-nm-size quasicrystals are isolated and homogeneously distributed in an amorphous matrix. The fracture strength and global strain, respectively, increase from 1921 MPa and 5.1% for as-cast BMG to 2084 MPa and 6.2% for partially crystallized BMG with the volume fraction of ∼ 7% quasicrystals. These improvements may be attributed to the structural similarity between quasicrystalline and amorphous phases. Stable low-energy interface between two phases may act as a source for multiple-shear-band formation. © 2003 American Institute of Physics.
Show PACS
62.25.-g Mechanical properties of nanoscale systems
61.44.Br Quasicrystals
61.43.Fs Glasses
62.20.F- Deformation and plasticity

β-phase tungsten nanorod formation by oblique-angle sputter deposition

Tansel Karabacak, Anupama Mallikarjunan, Jitendra P. Singh, Dexian Ye, Gwo-Ching Wang, and Toh-Ming Lu

Appl. Phys. Lett. 83, 3096 (2003); http://dx.doi.org/10.1063/1.1618944 (3 pages) | Cited 47 times

Online Publication Date: 7 October 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report the creation of an unusual simple cubic β-phase W(100) nanorods with a pyramidal tip having four (110) facets using an oblique-angle sputter deposition technique with substrate rotation (also known as glancing-angle deposition). During the oblique-angle deposition, both β-phase W(100) and α-phase W(110) islands exist at the initial stages of growth. The β-phase W(100) islands grow taller due to the lower adatom mobility on these islands. The taller islands survive in the competition and form isolated nanorods in the later stages of growth. This is in contrast to the sputter deposition at normal incidence, where only the thermodynamically stable bcc α-phase W(110) polycrystalline films were formed when the film grows to a certain thickness. © 2003 American Institute of Physics.
Show PACS
68.55.Nq Composition and phase identification
81.15.Cd Deposition by sputtering
61.46.-w Structure of nanoscale materials
81.07.Bc Nanocrystalline materials

Thermal expansion coefficient of hydrogenated amorphous carbon

F. C. Marques, R. G. Lacerda, A. Champi, V. Stolojan, D. C. Cox, and S. R. P. Silva

Appl. Phys. Lett. 83, 3099 (2003); http://dx.doi.org/10.1063/1.1619557 (3 pages) | Cited 30 times

Online Publication Date: 7 October 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The coefficient of thermal expansion (CTE) of hydrogenated amorphous carbon (a-C:H) was investigated as a function of the concentration of sp2 hybridization. The CTE, determined using the thermally induced bending technique, depends on the concentration of sp2 bonded carbon, increasing to the value of graphite as the sp2 concentration approaches 100%. By using a combination of the thermally induced bending technique and nanohardness measurements, we extract separately the Young’s modulus and Poisson’s ratio of the a-C:H films as function of the sp2 concentration. © 2003 American Institute of Physics.
Show PACS
65.60.+a Thermal properties of amorphous solids and glasses: heat capacity, thermal expansion, etc.
62.20.D- Elasticity
62.20.Qp Friction, tribology, and hardness
back to top
RSS Feeds

ac conductivity and conduction mechanism of NaNbO3 semiconductor antiferroelectric ceramic: A relaxational approach at high temperature

M. A. L. Nobre and S. Lanfredi

Appl. Phys. Lett. 83, 3102 (2003); http://dx.doi.org/10.1063/1.1618016 (3 pages)

Online Publication Date: 7 October 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The electric properties of the sodium niobate perovskite ceramic were investigated by impedance spectroscopy in the frequency range from 5 Hz to 13 MHz and from room temperature up to 1073 K, in a thermal cycle. Both capacitance and conductivity exhibit an anomaly at around 600 K as a function of the temperature and frequency. The electric conductivity as a function of angular frequency σ(ω) follows the relation σ(ω) = Aωs. The values of the exponent s lie in the range 0.15 ⩽ s ⩽ 0.44. These results were discussed considering the conduction mechanism as being a type of polaron hopping. © 2003 American Institute of Physics.
Show PACS
77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates
72.20.Fr Low-field transport and mobility; piezoresistance
72.80.Jc Other crystalline inorganic semiconductors

Temperature-dependent Cl2/Ar plasma etching of bulk single-crystal ZnO

W. T. Lim, I. K. Baek, J. W. Lee, E. S. Lee, M. H. Jeon, G. S. Cho, Y. W. Heo, D. P. Norton, and S. J. Pearton

Appl. Phys. Lett. 83, 3105 (2003); http://dx.doi.org/10.1063/1.1618373 (3 pages) | Cited 16 times

Online Publication Date: 7 October 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The etch rate of bulk ZnO in Cl2/Ar high density plasmas was found to be thermally activated with an activation energy of ∼0.31 eV at <300 °C. The rate-limiting step appears to be the ion-assisted desorption of the ZnClX etch products. The threshold ion energy for etching ZnO at 150 °C in Cl2/Ar is ∼170 eV, obtained by fitting to a model of ion-enhanced sputtering by a collision-cascade process. The amount of residual chlorine on the ZnO surface decreases with increasing etch temperature, but there is a tendency for the surface to become Zn-rich and roughen at elevated temperatures (>200 °C). © 2003 American Institute of Physics.  
Show PACS
81.65.Cf Surface cleaning, etching, patterning
81.05.Dz II-VI semiconductors
52.77.Bn Etching and cleaning
68.43.Mn Adsorption kinetics

High mobility organic transistors fabricated from single pentacene microcrystals grown on a polymer film

Guanzhong Wang, Yi Luo, and Peter H. Beton

Appl. Phys. Lett. 83, 3108 (2003); http://dx.doi.org/10.1063/1.1617375 (3 pages) | Cited 21 times

Online Publication Date: 7 October 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Isolated multilayer, bilayer, and monolayer crystals of pentacene are grown on polymer thin films. Source and drain contacts are formed to individual crystallites and transistor operation, based on the formation of an inversion layer at the pentacene/polymer interface is demonstrated for multilayers, trilayers, and bilayers. Hole inversion layers are formed with mobilities up to 1.2 cm2/V s for multilayer crystals, while a reduced mobility is observed for trilayers and bilayers. © 2003 American Institute of Physics.
Show PACS
85.30.Tv Field effect devices

Dilute nitride based double-barrier quantum-well infrared photodetector operating in the near infrared

E. Luna, M. Hopkinson, J. M. Ulloa, A. Guzmán, and E. Muñoz

Appl. Phys. Lett. 83, 3111 (2003); http://dx.doi.org/10.1063/1.1618931 (3 pages) | Cited 23 times

Online Publication Date: 7 October 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Near-infrared detection is reported for a double-barrier quantum-well infrared photodetector based on a 30-Å GaAs1−yNy (y ≈ 0.01) quantum well. The growth procedure using plasma-assisted molecular-beam epitaxy is described. The as-grown sample exhibits a detection wavelength of 1.64 μm at 25 K. The detection peak strengthens and redshifts to 1.67 μm following rapid thermal annealing at 850 °C for 30 s. The detection peak position is consistent with the calculated band structure based on the band-anticrossing model for nitrogen incorporation into GaAs. © 2003 American Institute of Physics.
Show PACS
85.60.Gz Photodetectors (including infrared and CCD detectors)
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy

Reliable strain determination method for InGaAsN/GaAs quantum wells using a simple photoluminescence measurement

N. J. Kim, Y. D. Jang, D. Lee, K. H. Park, Weon G. Jeong, and J. W. Jang

Appl. Phys. Lett. 83, 3114 (2003); http://dx.doi.org/10.1063/1.1618371 (3 pages) | Cited 3 times

Online Publication Date: 7 October 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We present a reliable method for determining the strain in InGaAsN quantum wells. The method uses the fact that the splitting between heavy hole and light hole energy levels depends mostly on the strain. We also found that the strain was largely relaxed in an In0.34Ga0.66As/GaAs quantum well, but recovered when a small amount of nitrogen was added to the In0.34Ga0.66As layer. © 2003 American Institute of Physics.
Show PACS
68.65.Fg Quantum wells
78.67.De Quantum wells
78.55.Cr III-V semiconductors

Ultrabroadband terahertz radiation from low-temperature-grown GaAs photoconductive emitters

Y. C. Shen, P. C. Upadhya, E. H. Linfield, H. E. Beere, and A. G. Davies

Appl. Phys. Lett. 83, 3117 (2003); http://dx.doi.org/10.1063/1.1619223 (3 pages) | Cited 42 times

Online Publication Date: 7 October 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Terahertz radiation was generated with a biased and asymmetrically excited low-temperature-grown GaAs photoconductive emitter, and characterized with a 20-μm-thick ZnTe crystal using free-space electro-optic sampling. Using a backward collection scheme, we obtained terahertz radiation with frequency components over 30 THz, the highest ever observed for photoconductive emitters. We present spectra over the whole frequency range between 0.3 and 20 THz, demonstrating the use of this source for ultrabroadband THz spectroscopy. © 2003 American Institute of Physics.
Show PACS
07.57.Hm Infrared, submillimeter wave, microwave, and radiowave sources
78.20.Jq Electro-optical effects
72.40.+w Photoconduction and photovoltaic effects

Influence of image force and many-body correction on electron mobility in ultrathin double gate silicon on insulator inversion layers

F. Gámiz, P. Cartujo-Cassinello, F. Jiménez-Molinos, J. E. Carceller, and P. Cartujo

Appl. Phys. Lett. 83, 3120 (2003); http://dx.doi.org/10.1063/1.1619217 (3 pages) | Cited 1 time

Online Publication Date: 7 October 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We study the influence of the image and exchange-correlation effects in double-gate silicon-on-insulator (DGSOI) devices, in the calculation of both charge distribution and electron mobility. The image and exchange correlation potentials produce a greater confinement of the carriers and, according to the uncertainty principle, a greater phonon scattering rate, which produces a decrease in electron mobility. Moreover, the influence of image and exchange-correlation potentials on electron mobility, while almost negligible for bulk silicon inversion layers, becomes increasingly important as the silicon thickness decreases, due to the effect of volume inversion in DGSOI inversion layers. These effects must then be taken into account in order to achieve a correct evaluation of the charge distribution and of mobility in DGSOI inversion layers. © 2003 American Institute of Physics.
Show PACS
73.40.Qv Metal-insulator-semiconductor structures (including semiconductor-to-insulator)

Quantitative measurement of the influence of growth interruptions on the Sb distribution of GaSb/GaAs quantum wells by transmission electron microscopy

M. Schowalter, A. Rosenauer, D. Gerthsen, M. Grau, and M.-C. Amann

Appl. Phys. Lett. 83, 3123 (2003); http://dx.doi.org/10.1063/1.1618380 (3 pages) | Cited 2 times

Online Publication Date: 7 October 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We investigated the influence of growth interruptions on the morphology of molecular-beam epitaxy grown GaSb/GaAs multiquantum-well structures by transmission electron microscopy (TEM). Profiles of the chemical composition of the GaSb layers were deduced from high-resolution TEM images with the lattice fringe analysis method. We found clear indications of segregation of Sb in GaAs-on-GaSb for a sample grown with growth interruption before and after the growth of the quantum wells. Its efficiency R = 0.78±0.03 was derived by fitting the measured composition profiles with the model of Muraki. Determination of the total amounts of deposited GaSb yields a higher amount of GaSb in a sample grown without interruption. © 2003 American Institute of Physics.
Show PACS
68.65.Fg Quantum wells
68.37.Lp Transmission electron microscopy (TEM)
back to top
RSS Feeds

Nitrogen effects on lowering specific junction resistance and suppressing Mn diffusion in a magnetic tunnel junction

Heejae Shim, B. K. Cho, Jin-Tae Kim, J. W. Choi, and Y. Park

Appl. Phys. Lett. 83, 3126 (2003); http://dx.doi.org/10.1063/1.1618381 (3 pages) | Cited 1 time

Online Publication Date: 7 October 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We investigated the annealing effects of a magnetic tunnel junction on the Fe bottom pinned layer, of which the top surface was exposed to nitrogen plasma for a few tens of seconds prior to the deposition of the Al layer. The nitrogen-treated junction shows a lower magnetoresistance (MR) ratio and specific junction resistance (RA) than the untreated normal junction. However, after annealing at 230 °C, the MR ratio of the nitrogen-treated junction recovers to optimal values of the normal junction, while the RA remains lower than that of the normal junction. Furthermore, the nitrogen-treated junction shows less reduction of MR ratio and RA value with annealing at 270 °C for 3 h than the normal junction. From x-ray photoelectron spectroscopy and auger electron spectroscopy depth profiles, it is found that the nitrogen, which was initially at an interface between Al and Fe, diffuses into both the Al and FeMn layers after annealing at 230 °C. It seems that the nitrogen plays an important role in reducing Mn diffusion, as well as in improving the junction properties. © 2003 American Institute of Physics.
Show PACS
85.75.-d Magnetoelectronics; spintronics: devices exploiting spin polarized transport or integrated magnetic fields
75.70.Cn Magnetic properties of interfaces (multilayers, superlattices, heterostructures)
73.40.Cg Contact resistance, contact potential
75.50.Bb Fe and its alloys
61.72.Cc Kinetics of defect formation and annealing
81.40.Gh Other heat and thermomechanical treatments
79.60.Jv Interfaces; heterostructures; nanostructures
61.72.S- Impurities in crystals
66.30.J- Diffusion of impurities

Co distribution in ferromagnetic rutile Co-doped TiO2 thin films grown by laser ablation on silicon substrates

Nguyen Hoa Hong, Joe Sakai, W. Prellier, and Awatef Hassini

Appl. Phys. Lett. 83, 3129 (2003); http://dx.doi.org/10.1063/1.1619227 (3 pages) | Cited 32 times

Online Publication Date: 7 October 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Pure rutile Co-doped TiO2 films were fabricated by the pulsed-laser-deposition technique on silicon substrates from a ceramic target. Under the right fabrication conditions, Co concentration in the films could be almost the same as in the target, and films under various conditions all are ferromagnetic well above room temperature. Even though Rutherford backscattering spectroscopy measurements show that Co atoms mostly localize near the surface of the films and exist less in deeper levels, other experimental evidence shows that the ferromagnetism does not come from Co segregations, but from the Co-doped TiO2 matrix. Rutile Ti1−xCoxO2 thin films grown by a very simple technique on low-cost silicon substrates showing a Curie temperature (TC) above 400 K appear to be very attractive to applications. © 2003 American Institute of Physics.
Show PACS
75.70.Ak Magnetic properties of monolayers and thin films
75.50.Dd Nonmetallic ferromagnetic materials
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
81.15.Fg Pulsed laser ablation deposition
82.80.Yc Rutherford backscattering (RBS), and other methods of chemical analysis
64.75.-g Phase equilibria
81.30.Mh Solid-phase precipitation
61.72.S- Impurities in crystals
75.30.Kz Magnetic phase boundaries (including classical and quantum magnetic transitions, metamagnetism, etc.)
75.40.-s Critical-point effects, specific heats, short-range order

Quantitative measurement of the ferromagnetic resonance signal by force detection

V. V. Naletov, V. Charbois, O. Klein, and C. Fermon

Appl. Phys. Lett. 83, 3132 (2003); http://dx.doi.org/10.1063/1.1614421 (3 pages) | Cited 9 times

Online Publication Date: 7 October 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A magnetic resonance force microscope is used to measure ΔMz, the change of longitudinal magnetization associated with the resonant absorption of microwave power in a ferromagnetic crystal. It is demonstrated that quantitative measurements of ΔMz can be obtained by analyzing the dipolar force exerted between a disk sample and a cylindrical probe magnet aligned and magnetized along their axis. Finite size effects are found to be important when probing the resonance in a micron-sized sample. © 2003 American Institute of Physics.
Show PACS
76.50.+g Ferromagnetic, antiferromagnetic, and ferrimagnetic resonances; spin-wave resonance
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects

Physical properties of single-crystalline fibers of the colossal-magnetoresistance manganite La0.7Ca0.3MnO3

C. A. Cardoso, F. M. Araujo-Moreira, M. R. B. Andreeta, A. C. Hernandes, E. R. Leite, O. F. de Lima, A. W. Mombrú, and R. Faccio

Appl. Phys. Lett. 83, 3135 (2003); http://dx.doi.org/10.1063/1.1619566 (3 pages) | Cited 1 time

Online Publication Date: 7 October 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We have grown high-quality single crystals of the colossal-magnetoresistance (CMR) material La0.7Ca0.3MnO3 by using the laser heated pedestal growth method. Samples were grown as fibers of different diameters, and with lengths of the order of centimeters. Their composition and structure were verified through x-ray diffraction, scanning electron microcopy with energy dispersive x-ray analysis and by Rietveld analysis. The quality of the crystalline fibers was confirmed by Laue and electron backscatter diffraction patterns. Rocking curves performed along the fiber axis revealed a half-height width of 0.073°. The CMR behavior was confirmed by electrical resistivity and magnetization measurements as a function of temperature. © 2003 American Institute of Physics.
Show PACS
75.47.Gk Colossal magnetoresistance
75.47.Lx Magnetic oxides
81.10.Jt Growth from solid phases (including multiphase diffusion and recrystallization)

Magnetic moment compensation in exchange-biased trilayers with antiparallel spin alignment

Yang-Hsiung Fan and Hubert Brückl

Appl. Phys. Lett. 83, 3138 (2003); http://dx.doi.org/10.1063/1.1619565 (3 pages) | Cited 8 times

Online Publication Date: 7 October 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Trilayers consisting of ferromagnetic rare earth and transition metals show an antiparallel exchange coupling of the individual layers. Thus, they can be exploited as hardmagnetic electrodes in spin valve stacks and magnetic tunnel junctions for sensors or memories. Magnetic tunnel junctions consisting of IrMn exchange-biased NiFe/Gd/NiFe trilayers show a compensation of the total magnetic moment at an appropriate choice of the individual layer thicknesses and temperature. This stack setup allows a sixfold enhancement of the exchange-bias field and a strong reduction of the Néel and edge stray field coupling in patterned elements. Therefore, such trilayers are proposed as an alternative for artificial ferrimagnets in the relevant devices. © 2003 American Institute of Physics.
Show PACS
75.70.Cn Magnetic properties of interfaces (multilayers, superlattices, heterostructures)
75.30.Et Exchange and superexchange interactions
75.30.Cr Saturation moments and magnetic susceptibilities
Page 2 of 4 Pages Previous Page Next Page | Jump to Page
Close

Google Calendar

ADVERTISEMENT

Go to AIP Home   © AIP Publishing LLC
close