jap banner
  • Volume/Page
  • Keyword
  • DOI
  • Citation
  • Advanced
   
 
 
 

Flickr Twitter iResearch App Facebook

BROWSE VOLUMES

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

1 Jun 1999

Volume 85, Issue 11, pp. 7505-7990

Return to All Sections
back to top
RSS Feeds

Electronic and structural properties of the pentanary alloy GaxIn1−xPySbzAs1−y−z

Kyurhee Shim and Herschel Rabitz

J. Appl. Phys. 85, 7705 (1999); http://dx.doi.org/10.1063/1.370575 (11 pages) | Cited 13 times

Full Text: | Download PDF

Show Abstract
The universal tight binding (UTB) model based on a modified pseudocell (MPC) is used to obtain the electronic band structure, band gaps, and the density of states (DOS) for the pentanary alloy GaxIn1−xPySbzAs1−y−z of dimension N = 3 (i.e., x, y, and z). The composition dependent local and alloy bond lengths of the alloy are formulated within the MPC, and the lattice matching conditions for several substrates are found by optimizing the bond length of the substrate to the alloy bond length. The principal band gaps [E(Γ),E(L),E(X)] of the alloy are calculated lattice matched to GaAs, InP, InAs, and GaSb. The main contribution of each component upon the DOS is investigated through observation of variations with composition. In addition, the band gap calculations are performed for the ternary (N = 1; GaxIn1−xP, GaPyAs1−y, and GaxIn1−xAs) and quaternary (N = 2; GaxIn1−xPyAs1−y) alloys which are limiting composition cases for the pentanary alloy GaxIn1−xPySbzAs1−y−z. The latter reduced results are in good agreement with available experimental data, thereby validating the UTB model. The UTB model may also be extended to treat higher dimensional material systems (N ≥ 4). © 1999 American Institute of Physics.
Show PACS
71.20.Nr Semiconductor compounds
61.66.Fn Inorganic compounds
61.50.Lt Crystal binding; cohesive energy
71.15.Ap Basis sets (LCAO, plane-wave, APW, etc.) and related methodology (scattering methods, ASA, linearized methods, etc.)

Photoacoustic frequency transmission technique: Electronic deformation mechanism in semiconductors

D. M. Todorović, P. M. Nikolić, and A. I. Bojičić

J. Appl. Phys. 85, 7716 (1999); http://dx.doi.org/10.1063/1.370576 (11 pages) | Cited 15 times

Full Text: | Download PDF

Show Abstract
A quantitative analysis of the electronic deformation (electronic strain) contribution to the photoacoustic signal in semiconductor samples was done. The photoacoustic (PA) effect was investigated as a function of the modulation frequency in a transmission detection configuration. The theoretical model for this configuration was given for the thermal and elastic processes besides the carrier transport characteristic and the relation for electronic elastic deformation was derived by the theory of the elastic thin plate vibrations. Analysis showed that the electronic deformation mechanisms can have an important infleucne on the PA signal in the frequency range typical for gas-microphone detection. The experimental photoacoustic data for Si samples were measured and they exhibited a satisfactory agreement with the theoretical model. © 1999 American Institute of Physics.
Show PACS
62.65.+k Acoustical properties of solids
43.35.Ud Thermoacoustics, high temperature acoustics, photoacoustic effect
78.20.hb Piezo-optical, elasto-optical, acousto-optical, and photoelastic effects
62.20.F- Deformation and plasticity
62.30.+d Mechanical and elastic waves; vibrations

Transient electron transport in wurtzite GaN, InN, and AlN

Brian E. Foutz, Stephen K. O’Leary, Michael S. Shur, and Lester F. Eastman

J. Appl. Phys. 85, 7727 (1999); http://dx.doi.org/10.1063/1.370577 (8 pages) | Cited 233 times

Full Text: | Download PDF

Show Abstract
Transient electron transport and velocity overshoot in wurtzite GaN, InN, and AlN are examined and compared with that which occurs in GaAs. For all materials, we find that electron velocity overshoot only occurs when the electric field is increased to a value above a certain critical field, unique to each material. This critical field is strongly dependent on the material, about 4 kV/cm for the case of GaAs but much higher for the III–nitride semiconductors: 140 kV/cm for GaN, 65 kV/cm for InN, and 450 kV/cm for AlN. We find that InN exhibits the highest peak overshoot velocity and that this velocity overshoot lasts over the longest distances when compared with GaN and AlN. Finally, using a one-dimensional energy–momentum balance approach, a simple model is used to estimate the cutoff frequency performance of nitride based heterojunction field effect transistors (HFETs) and a comparison is made to recently fabricated AlGaN/GaN HFETs. © 1999 American Institute of Physics.
Show PACS
72.20.Ht High-field and nonlinear effects
72.80.Ey III-V and II-VI semiconductors
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping

Grain size-dependent electrical properties of nanocrystalline ZnO

Ce-Wen Nan, A. Tschöpe, S. Holten, H. Kliem, and R. Birringer

J. Appl. Phys. 85, 7735 (1999); http://dx.doi.org/10.1063/1.370578 (6 pages) | Cited 33 times

Full Text: | Download PDF

Show Abstract
Undoped and Bi-doped nanocrystalline ZnO was prepared by the inert gas condensation method. Samples of different grain sizes were obtained by annealing treatments at various temperatures. The dc and ac electrical conductivity of undoped and Bi-doped nanocrystalline ZnO was investigated as a function of grain size. In dc measurements, nanocrystalline ZnO of small grain size (<20 nm) exhibited time dependent currents similar to those found in other dielectric solids and which are characteristic for space charge limited conduction. However, unusually long transient times of up to 300 s were observed. Similar samples of larger grain sizes (>40 nm) did not exhibit time dependent conduction but exhibited ohmic behavior. This difference in dc conductivity is discussed in terms of the grain size dependence of the average trap density. A small amount of Bi dopant had no measurable effect on the electrical behavior in the small grain size range but resulted in higher specimen resistance in the large grain size range. ac electrical properties were characterized by impedance spectroscopy. The impedance spectra of undoped and Bi-doped samples of small grain sizes were rather similar and exhibited two semicircles. In contrast, the impedance spectra of samples with larger grain sizes were single, depressed circles with much higher impedances for the Bi-doped sample, in agreement with the dc measurements. A consistent assignment of the contributions due to bulk conductivity, porosity, and grain boundary effects to the overall impedance is presented. © 1999 American Institute of Physics.
Show PACS
72.80.Ey III-V and II-VI semiconductors
72.20.Ht High-field and nonlinear effects
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping
61.72.Cc Kinetics of defect formation and annealing
61.72.Mm Grain and twin boundaries

Theoretical and experimental study of charge carrier kinetics in crystalline silicon

Olaf Hahneiser and Marinus Kunst

J. Appl. Phys. 85, 7741 (1999); http://dx.doi.org/10.1063/1.370579 (14 pages) | Cited 10 times

Full Text: | Download PDF

Show Abstract
A model simulating excess charge carrier kinetics in Si wafers was developed taking into account space charge fields and surface recombination. This model was applied to experimental data obtained by contactless transient and frequency resolved photoconductivity measurements of silicon wafers with accumulation or depletion layers at the surface. It is shown that a surface accumulation layer has only a minor influence and surface recombination can be analyzed with a surface recombination velocity weakly depending on the excess carrier concentration. At low injection level a surface depletion layer leads to a strongly nonlinear behavior of the photoconductivity due to excess charge carriers stored in the space charge region. The presence of these charge carriers is also revealed by the tail of the transient photoconductivity signal characterized by a decay time longer than the volume lifetime. At higher injection level the contribution of these charge carriers to the photoconductivity can be neglected and the data can be analyzed with the (differential) surface recombination velocity. © 1999 American Institute of Physics.
Show PACS
72.80.Cw Elemental semiconductors
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping
77.22.Jp Dielectric breakdown and space-charge effects
73.25.+i Surface conductivity and carrier phenomena
72.40.+w Photoconduction and photovoltaic effects
72.20.Ht High-field and nonlinear effects

Photoconductivity measurement of polymers by x-ray absorption fine structure

T. D. Hu, Y. N. Xie, T. Liu, X. Ju, K. Ibrahim, Y. L. Jin, L. Chen, and C. Z. Yang

J. Appl. Phys. 85, 7755 (1999); http://dx.doi.org/10.1063/1.370580 (4 pages)

Full Text: | Download PDF

Show Abstract
Photoconductivity spectra measurement of polymers at x-ray energies around the Zn and Co K edges shows obvious x-ray absorption fine structure oscillations. The photoconductivity spectra obtained for gapped and sandwiched electrode geometric samples indicate that the shape of photoconductivity spectrum depends on the electrode configuration of the samples. The thickness of the conduction layer can be estimated from the photoconductivity spectrum. © 1999 American Institute of Physics.
Show PACS
72.40.+w Photoconduction and photovoltaic effects
78.70.Dm X-ray absorption spectra

ZnSe/GaAs band-alignment determination by deep level transient spectroscopy and photocurrent measurements

A. Souifi, R. Adhiri, R. Le Dantec, G. Guillot, P. Uusimaa, A. Rinta-Möykky, and M. Pessa

J. Appl. Phys. 85, 7759 (1999); http://dx.doi.org/10.1063/1.370581 (5 pages) | Cited 5 times

Full Text: | Download PDF

Show Abstract
Using deep level transient spectroscopy and photocurrent measurements we have investigated Schottky contacts formed on p-isotype Zn(SSe)/GaAs heterostructures grown by molecular beam epitaxy on p-GaAs(100) substrates. A deep level located at 0.6 eV above the ZnSe valence band is observed in agreement with literature data for p-type ZnSe, and is used as a reference level for the understanding of photocurrent transitions in the 0.8–3.0 eV energy range. The threshold energies obtained on a series of Zn(SSe)/GaAs samples are explained in terms of absorption processes from the ZnSe and GaAs valence bands, and from the nitrogen acceptor level and a deep level of the ZnSe layers located at 0.1 and 0.6 eV above the valence band maximum, respectively. These absorption processes towards the ZnSe and GaAs conduction bands have been finally used to give the values of the conduction and valence band offsets at p-ZnSe/p-GaAs interface. Our experimental data gives ΔEc = 0.25±0.03 eV and ΔEv = 1.00±0.05 eV in agreement with literature data for Zn-rich interfaces. © 1999 American Institute of Physics.
Show PACS
73.30.+y Surface double layers, Schottky barriers, and work functions
73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
73.20.Hb Impurity and defect levels; energy states of adsorbed species

Unambiguous distinction between diffusion length and surface recombination velocity of solar cells at different excitation levels

P. Wawer, M. Rochel, and H.-G. Wagemann

J. Appl. Phys. 85, 7764 (1999); http://dx.doi.org/10.1063/1.370582 (4 pages) | Cited 1 time

Full Text: | Download PDF

Show Abstract
In this work we present a conclusive separation of bulk and surface recombination properties of solar cells. For this purpose, bifacial silicon solar cells were fabricated. The backside differential spectral response of the cells has been measured in the presence of bias light, both with and without backside passivation by means of corona charging on top of a thermal oxide. Employing the common one-dimensional Shockley model, the measurement curves have been simulated. This enables the base diffusion length to be distinguished from the backside surface recombination velocity. As such, their values have been determined individually. Repeating this procedure for different intensities of bias light has yielded the nonlinear behavior of the recombination mechanisms. By applying the Schockley–Read–Hall recombination theory, it was deduced that Fe interstitials presumably are the predominant bulk recombination centers. © 1999 American Institute of Physics.
Show PACS
84.60.Jt Photoelectric conversion
73.25.+i Surface conductivity and carrier phenomena
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping
73.50.Gr Charge carriers: generation, recombination, lifetime, trapping, mean free paths
73.40.Lq Other semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions

Temperature dependence of the electron affinity difference between Si and SiO2 in polysilicon (n+)–oxide–silicon (p) structures: Effect of the oxide thickness

G. Salace, A. Hadjadj, C. Petit, and M. Jourdain

J. Appl. Phys. 85, 7768 (1999); http://dx.doi.org/10.1063/1.370583 (6 pages) | Cited 11 times

Full Text: | Download PDF

Show Abstract
The variations with temperature of the Fowler–Nordheim (FN) emission in metal–oxide–semiconductor structures when the injecting electrode is the degenerate polysilicon gate (n+) are investigated. The temperature dependence of the electron affinity difference Φ between Si and SiO2 and of the barrier height Φb for three oxide thicknesses (5, 7, and 12 nm) are analyzed. The results are numerically derived from the exact integral expression of the FN current as functions of temperature varying from 25 to 300 °C. The variation with temperature of both the obtained Φ and dΦ/dT parameters at the polysilicon (n+)–oxide barrier are discussed with respect to the literature data. © 1999 American Institute of Physics.
Show PACS
73.40.Qv Metal-insulator-semiconductor structures (including semiconductor-to-insulator)

Scanning capacitance microscope methodology for quantitative analysis of p-n junctions

V. V. Zavyalov, J. S. McMurray, and C. C. Williams

J. Appl. Phys. 85, 7774 (1999); http://dx.doi.org/10.1063/1.370584 (10 pages) | Cited 1 time

Full Text: | Download PDF

Show Abstract
Quantification of dopant profiles in two dimensions (2D) for p-n junctions has proven to be a challenging problem. The scanning capacitance microscope (SCM) capability for p-n junction imaging has only been qualitatively demonstrated. No well-established physical model exists yet for the SCM data interpretation near the p-n junction. In this work, the experimental technique and conversion algorithm developed for nonjunction samples are applied to p-n junction quantification. To understand the SCM response in the active p-n junction region, an electrical model of the junction is proposed. Using one-dimensional secondary ion mass spectrometry (SIMS) data, the carrier distribution in the vertical dimension is calculated. The SIMS profile and carrier distribution is then compared with the SCM data converted using a first-order model. It is shown that for a certain class of profiles, the SCM converted dopant profile fits well to the SIMS data in one dimension. Under this condition, it is possible to identify the metallurgical p-n junction position in two dimensions. Examples of 2D metallurgical p-n junction delineation are presented. In addition, the SCM ability to locate the 2D position of the intrinsic point in the p-n junction depletion region is demonstrated. The SCM probe tip size is found to be a major factor limiting the SCM accuracy on shallow profiles. On junctions with shallow profiles, the SCM tip interacts with carriers on both sides of the junction. As a consequence, a decrease in accuracy and spatial resolution is observed using a first-order conversion algorithm. © 1999 American Institute of Physics.
Show PACS
73.40.Lq Other semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
61.72.S- Impurities in crystals
07.79.Lh Atomic force microscopes
84.37.+q Measurements in electric variables (including voltage, current, resistance, capacitance, inductance, impedance, and admittance, etc.)

Pt/PbZrxTi1−xO3 interfacial reaction and Schottky barrier formation studied by x-ray photoelectron spectroscopy: Effect of H2 and O2 annealing

Shinichiro Takatani, Hiroshi Miki, Keiko Kushida-Abdelghafar, and Kazuyoshi Torii

J. Appl. Phys. 85, 7784 (1999); http://dx.doi.org/10.1063/1.370585 (8 pages) | Cited 23 times

Full Text: | Download PDF

Show Abstract
The Pt/PbZrxTi1−xO3 (PZT) interfacial reaction caused by low-temperature (320 °C) annealing and resulting change in the surface Fermi level position (Schottky barrier height) has been studied by using in vacuo x-ray photoelectron spectroscopy (XPS). A thin (2 nm) Pt layer was deposited on a polycrystalline PZT film and annealed in 0.5-Torr H2 and O2 in a chamber connected to the XPS chamber. For the PZT samples annealed prior to Pt deposition, a small amount of metallic Pb was produced after the Pt deposition. The annealing also moved the surface Fermi level (EF) at the Schottky interface toward the conduction band minimum (EC) of PZT by 0.4 eV, as evidenced by the band-bending shift of the PZT core levels. Excess metallic states appeared in the valence-band spectra of an annealed bare PZT surface. There was no appreciable annealing-atmosphere dependence in the amount of metallic Pb produced and surface EF position at the PT/PZT interface. However, a clear annealing-atmosphere dependence was observed for the samples annealed after the Pt deposition. The H2 annealing enhanced the production of metallic Pb, whereas the O2 annealing suppressed the metallic Pb formation. The H2 annealing moved the surface EF toward EC by 1.0 eV, whereas the O2 annealing caused no measurable change in the surface EF position. The catalytic effect of Pt during the annealing was postulated to explain the observed annealing-atmosphere dependence. © 1999 American Institute of Physics.
Show PACS
68.35.Fx Diffusion; interface formation
73.30.+y Surface double layers, Schottky barriers, and work functions
73.40.Ns Metal-nonmetal contacts
79.60.Jv Interfaces; heterostructures; nanostructures
66.30.Ny Chemical interdiffusion; diffusion barriers
77.55.-g Dielectric thin films
77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates
73.20.At Surface states, band structure, electron density of states
85.50.-n Dielectric, ferroelectric, and piezoelectric devices

Near-noble transition-metal-based ohmic contacts to p-InP: Comparison of Ni and Pd as a base metal

Akira Yamaguchi, Hirokuni Asamizu, Takeshi Okada, Yasuhiro Iguchi, Tadashi Saitoh, Yasuo Koide, and Masanori Murakami

J. Appl. Phys. 85, 7792 (1999); http://dx.doi.org/10.1063/1.370586 (5 pages) | Cited 2 times

Full Text: | Download PDF

Show Abstract
The electrical properties were compared for near-noble transition-metal-based ohmic contacts with a M/Zn/M (M=Ni, Pd) sandwiched structure prepared on p-type InP. The minimum contact resistivities of ∼ 7×10−5 Ω cm2 were obtained in both the NiZn and PdZn contacts, while the process window for the annealing time of the PdZn contacts was much wider than that of the NiZn contacts. From x-ray diffraction and cross-sectional electron microscopic study at the metal/InP interfaces, it was found that ternary compounds such as Ni2.7InP and Pd2InP were formed at the Ni/InP and Pd/InP interfaces, respectively. However, the Ni2.7InP compounds were not stable at annealing temperatures above 300 °C, which is the primary reason of poor thermal stability of the NiZn contacts, while the Pd2InP compound was stable at such high temperatures. Selection of a suitable base metal for InP ohmic contacts was also discussed. © 1999 American Institute of Physics.
Show PACS
73.40.Ns Metal-nonmetal contacts
61.72.Cc Kinetics of defect formation and annealing
68.60.Dv Thermal stability; thermal effects
73.40.Cg Contact resistance, contact potential
66.30.Ny Chemical interdiffusion; diffusion barriers

Interface polariton modes in GaAs/AlAs superlattices with randomly distributed layer thickness

Xiaoshuang Chen, Xingquan Liu, Wei Lu, S. C. Shen, and Akio Sasaki

J. Appl. Phys. 85, 7797 (1999); http://dx.doi.org/10.1063/1.370587 (6 pages) | Cited 1 time

Full Text: | Download PDF

Show Abstract
We study here the dispersion relation and propagation of the interface polariton modes in specially constructed disordered GaAs/AlAs superlattices by using the transfer matrix method. The calculation of dispersion relation shows that the polariton modes exist only in two frequency regions, occur in some minibands and some isolated modes in each polariton band due to disordered effect and exhibit only small shift by varying the degree of thickness randomness, which are qualitatively in agreement with the experimental conclusions. We also find that some modes of interface polaritons with special frequencies are completely unscattered by randomness and can propagate through the structure, in contrast to the localized theory of one-dimensional (1D) disordered systems, while the other modes rapidly decay and are completely scattered. These results can be used to obtain the more realistic photonic band gaps and locations of the resonant photonic states in the 1D systems. This provides a possibility of building a high-quality optical filter. © 1999 American Institute of Physics.
Show PACS
73.20.Mf Collective excitations (including excitons, polarons, plasmons and other charge-density excitations)
71.36.+c Polaritons (including photon-phonon and photon-magnon interactions)
63.22.-m Phonons or vibrational states in low-dimensional structures and nanoscale materials
42.70.Qs Photonic bandgap materials
78.66.Fd III-V semiconductors

Determination of barrier oxidation states in spin dependent tunneling structures

Manish Sharma, Shan X. Wang, and Janice H. Nickel

J. Appl. Phys. 85, 7803 (1999); http://dx.doi.org/10.1063/1.370588 (4 pages) | Cited 8 times

Full Text: | Download PDF

Show Abstract
X-ray photoelectron spectroscopy (XPS) was used to characterize spin dependent tunneling (SDT) structures using plasma oxidized Ta as the insulating barrier. We are able to determine the relative proportion of the different oxidation states of the insulating barrier material. Information available from this technique includes barrier oxidation states, thickness, and completeness of oxidation. Information on the electrodes is also obtained: specifically, Ta is found to diffuse into NiFe, and oxidation of Ni is observed. XPS is shown to be a powerful tool in characterizing the materials sets that comprise SDT devices. © 1999 American Institute of Physics.
Show PACS
73.40.Gk Tunneling
81.65.Mq Oxidation
79.60.Jv Interfaces; heterostructures; nanostructures
73.50.Jt Galvanomagnetic and other magnetotransport effects (including thermomagnetic effects)
75.70.Cn Magnetic properties of interfaces (multilayers, superlattices, heterostructures)

Room-temperature anisotropic, thermoelectric, and electrical properties of n-type (Bi2Te3)90 (Sb2Te3)5 (Sb2Se3)5 and compensated p-type (Sb2Te3)72 (Bi2Te3)25 (Sb2Se3)3 semiconductor alloys

P. J. Taylor, J. R. Maddux, W. A. Jesser, and F. D. Rosi

J. Appl. Phys. 85, 7807 (1999); http://dx.doi.org/10.1063/1.370589 (7 pages) | Cited 9 times

Full Text: | Download PDF

Show Abstract
The anisotropy ratios (parallel to the c axis versus perpendicular to the c axis) for the electrical resistivity, Seebeck coefficient, and thermal conductivity of horizontal Bridgman-grown n-type (Bi2Te3)90 (Sb2Te3)5 (Sb2Se3)5 and p-type (Sb2Te3)72 (Bi2Te3)25 (Sb2Se3)3 were measured at 300 K. The orientation having the largest thermoelectric figure of merit was perpendicular to the zone axis of the c planes (along the natural growth direction). For the n-type alloy, the maximum thermoelectric figure of merit was determined to be 3.2×10−3/K. For the p-type alloy, the maximum thermoelectric figure of merit was determined to be 3.6×10−3/K when compensated with tellurium only, and 3.8×10−3/K when compensated with both tellurium and iodine. These values represent a significant increase over previously reported p-type thermoelectric figure of merit values. Hall coefficient data coupled with Seebeck coefficient measurements suggest a difference in carrier transport phenomena caused by an increased compensation of holes in the p-type alloy without the deleterious precipitation of the tellurium-rich second phase. © 1999 American Institute of Physics.
Show PACS
72.20.Pa Thermoelectric and thermomagnetic effects
72.80.Jc Other crystalline inorganic semiconductors
72.20.My Galvanomagnetic and other magnetotransport effects
72.20.Fr Low-field transport and mobility; piezoresistance
66.70.-f Nonelectronic thermal conduction and heat-pulse propagation in solids; thermal waves

Quantitative characterization of ion-induced SiO2/Si interface traps by means of MeV He single-ion irradiation

M. Koh, I. Ohdomari, K. Igarashi, T. Matsukawa, and S. Sawara

J. Appl. Phys. 85, 7814 (1999); http://dx.doi.org/10.1063/1.370590 (5 pages) | Cited 1 time

Full Text: | Download PDF

Show Abstract
The dependencies of MeV He single-ion-induced interface traps on oxide thickness and oxide electric fields Eox during irradiation was investigated quantitatively with a single-ion microprobe. Under a negative electric field, the number of interface traps induced by a single ion becomes constant at about 0.1 regardless of both the oxide thickness and oxide electric field. Under a positive electric field, the generation rate of interface traps per ion for thicker oxide metal–oxide–semiconductor field-effect transistors (MOSFETs) is greater than that for thinner oxide MOSFETs. We also found that the generation rates increase with dependence on the oxide electric field of Eox0.2, regardless of the oxide thicknesses. The field dependence of interface traps under a positive electric field was found to be very similar to that of oxide trapped holes. The causes of this dependence are discussed comprehensibly. © 1999 American Institute of Physics.
Show PACS
73.20.Hb Impurity and defect levels; energy states of adsorbed species
61.82.Fk Semiconductors
73.40.Qv Metal-insulator-semiconductor structures (including semiconductor-to-insulator)
85.30.Tv Field effect devices
61.80.Jh Ion radiation effects
61.82.Ms Insulators

Vortex dynamics of Nb variable-thickness bridges measured by direct flux detection method

S. Hirano, Y. Hirata, S. Kuriki, M. Matsuda, T. Morooka, and S. Nakayama

J. Appl. Phys. 85, 7819 (1999); http://dx.doi.org/10.1063/1.370591 (5 pages) | Cited 4 times

Full Text: | Download PDF

Show Abstract
In order to study the dynamical behavior of vortices moving through superconducting thin film devices, we constructed a probe having a concentric thin-film planar gradiometer coupled to a direct current SQUID. The probe was designed to directly detect the flux generated by a single vortex, based on the monopole approximation. Measurements of static current–voltage (I–V) and flux noise characteristics were made for variable-thickness bridges (VTB) made on epitaxial Nb films. The critical current was unambiguously determined from the onset of vortex motion. Multiple step noise of the flux with a minimum step height of 0.28Φ0 was observed above the critical current in the time traces. This step height is in agreement with the numerical calculation for single vortex motion, confirming the validity of the monopole approximation. It is suggested that the multiple step noise is generated by the successive entry of single vortices into the bridge. VTBs made on polycrystalline Nb films were also measured. The I–V characteristic showed asymmetric voltage increases and a multiple peak structure of the flux noise was observed above the critical current, suggesting the successive depinning of trapped vortices as flux bundles from widely distributed pinning potentials. © 1999 American Institute of Physics.
Show PACS
85.25.Cp Josephson devices
74.25.Uv Vortex phases (includes vortex lattices, vortex liquids, and vortex glasses)
74.78.-w Superconducting films and low-dimensional structures
74.70.Ad Metals; alloys and binary compounds (including A15, MgB2, etc.)
74.25.Sv Critical currents
74.50.+r Tunneling phenomena; Josephson effects
74.40.-n Fluctuation phenomena

Interparticle interactions and time effects in very thin Fe–SiO2 granular films

D. Otte, J. L. Weston, J. N. Zhou, and J. A. Barnard

J. Appl. Phys. 85, 7824 (1999); http://dx.doi.org/10.1063/1.370592 (4 pages) | Cited 1 time

Full Text: | Download PDF

Show Abstract
Time decay and remanence measurements have been made on a series of very thin Fe–SiO2 granular thin films of varying composition. The susceptibility and the magnetic viscosity decreases drastically when the film thickness is thin enough to reach a two-dimensional arrangement of the granules. The measured values of the magnetic viscosity are very low (2% loss per decade) in the thinnest films so that further investigations in granular magnetic systems with higher anisotropy promise greater advantages for recording media. © 1999 American Institute of Physics.
Show PACS
75.70.Ak Magnetic properties of monolayers and thin films
75.50.Ss Magnetic recording materials
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
75.30.Cr Saturation moments and magnetic susceptibilities
75.30.Gw Magnetic anisotropy
75.50.Bb Fe and its alloys

Magnetostrictive bending of an anisotropic free crystal substrate: Analytical and numerical solutions

P. Farber, M. Hörmann, M. Bischoff, and H. Kronmüller

J. Appl. Phys. 85, 7828 (1999); http://dx.doi.org/10.1063/1.370593 (5 pages) | Cited 7 times

Full Text: | Download PDF

Show Abstract
A model to calculate the effective elastic modulus of a single crystal cantilever used as a substrate for magnetostrictive measurements of thin films is given. Calculations are presented for Si (110), sapphire (1math00) (M plane) and (1math10) (A plane) cantilevers. Numerical calculations using the finite element method for sapphire show a very high accuracy of the proposed model. © 1999 American Institute of Physics.
Show PACS
75.80.+q Magnetomechanical effects, magnetostriction
62.20.F- Deformation and plasticity
81.40.Lm Deformation, plasticity, and creep
62.20.D- Elasticity
81.40.Jj Elasticity and anelasticity, stress-strain relations
68.35.Gy Mechanical properties; surface strains
75.70.Ak Magnetic properties of monolayers and thin films

Giant magnetoelastic response in MnAs

V. A. Chernenko, L. Wee, P. G. McCormick, and R. Street

J. Appl. Phys. 85, 7833 (1999); http://dx.doi.org/10.1063/1.370594 (5 pages) | Cited 30 times

Full Text: | Download PDF

Show Abstract
MnAs has been prepared from elemental powders using a modified ball-milling technique, followed by hot pressing and subsequent annealing. Giant magnetic field-induced uniaxial strains of up to 0.7% were observed in a temperature range above the Curie temperature (TC = 305 K). Dilatometric and magnetization measurements showed that the strains were associated with the volume change accompanying a field-induced magnetostructural paramagnetic to ferromagnetic transition above TC. The occurrence of a tricritical point (TCP) in temperature-field space, where the two low temperature phases and the high temperature NiAs-type phase are identical was shown to be responsible for the decrease of the magnitude of both the maximum strain and magnetization change with increasing temperature while approaching the TCP along the line of the first-order transitions. The coordinates of the TCP are approximately Ttr=405 K and Htr=165 kOe. © 1999 American Institute of Physics.
Show PACS
75.80.+q Magnetomechanical effects, magnetostriction
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
75.30.Kz Magnetic phase boundaries (including classical and quantum magnetic transitions, metamagnetism, etc.)
75.40.-s Critical-point effects, specific heats, short-range order
75.50.Dd Nonmetallic ferromagnetic materials

Angle dependence of the ferromagnetic resonance linewidth and two magnon losses in pulsed laser deposited films of yttrium iron garnet, MnZn ferrite, and NiZn ferrite

Anuj K. Srivastava, Michael J. Hurben, Michael A. Wittenauer, Pavel Kabos, Carl E. Patton, R. Ramesh, Paul C. Dorsey, and Douglas B. Chrisey

J. Appl. Phys. 85, 7838 (1999); http://dx.doi.org/10.1063/1.370595 (11 pages) | Cited 15 times

Full Text: | Download PDF

Show Abstract
Shorted waveguide ferromagnetic resonance (FMR) measurements were made at 9.5 GHz for pulsed laser deposited yttrium iron garnet (YIG), MnZn ferrite, and NiZn ferrite films with thicknesses of 1.8, 0.5, and 1.5 μm, respectively. The FMR field versus the field angle confirmed the operational assumption of a uniform mode response. For the YIG, the linewidth was 10 Oe when the external field and magnetization vectors were perpendicular to the disk (perpendicular FMR) and increased smoothly to a maximum value of 27 Oe when the field and magnetization were in the film plane (parallel FMR). For the MnZn, the linewidth was 49 Oe at perpendicular FMR, increased with the angle between the film normal and the external field to a broad maximum of 80 Oe at 35°, and then dropped to 65 Oe at parallel FMR. For the NiZn, the linewidth was 310 Oe at perpendicular FMR, increased with the field angle to a broad maximum of 1530 Oe at 45°, and then dropped to 960 Oe at parallel FMR. The linewidths were larger than predicted for reasonable values of the Landau–Lifshitz damping and showed angle dependences which indicated nonintrinsic contributions to the loss. Two magnon scattering was used to model these linewidth differences. The angle dependences of the excess linewidths show qualitative agreement with the two magnon predictions, with inhomogeneity sizes in the submicron range and volume fractions below 1%. © 1999 American Institute of Physics.
Show PACS
75.50.Gg Ferrimagnetics
75.70.Ak Magnetic properties of monolayers and thin films
76.50.+g Ferromagnetic, antiferromagnetic, and ferrimagnetic resonances; spin-wave resonance
75.30.Ds Spin waves
81.15.Fg Pulsed laser ablation deposition
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects

Inductive measurement of ultrafast magnetization dynamics in thin-film Permalloy

T. J. Silva, C. S. Lee, T. M. Crawford, and C. T. Rogers

J. Appl. Phys. 85, 7849 (1999); http://dx.doi.org/10.1063/1.370596 (14 pages) | Cited 150 times

Full Text: | Download PDF

Show Abstract
An inductive technique for the measurement of dynamical magnetic processes in thin-film materials is described. The technique is demonstrated using 50 nm films of Permalloy (Ni81Fe19). Data are presented for impulse- and step-response experiments with the applied field pulse oriented in the plane of the film and transverse to the anisotropy axis. Rotation times as short as 200 ps and free oscillations of the magnetization after excitation are clearly observed. The oscillation frequency increases as the dc bias field parallel to the anisotropy axis increases as predicted by classical gyromagnetic theory. The data are fitted to the Landau–Lifshitz equation, and damping parameters are determined as a function of dc bias field. Damping for both impulse and step excitations exhibits a strong dependence on bias field. Damping for step excitations is characterized by an anomalous transient damping which rapidly increases at low dc bias field. Transformation of the data to the frequency domain reveals a higher order precessional mode which is also preferentially excited at low dc bias fields. A possible source for both phenomena is precessional mode saturation for large peak rotations. The technique has the potential for 20 ps resolution, although only 120 ps resolution is demonstrated due to the limited bandwidth of the waveguides used. © 1999 American Institute of Physics.
Show PACS
75.70.Ak Magnetic properties of monolayers and thin films
75.50.Bb Fe and its alloys
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
75.30.Gw Magnetic anisotropy
Return to All Sections
Close

Google Calendar

ADVERTISEMENT

Go to AIP Home   © AIP Publishing LLC
close