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

12 Feb 2001

Volume 78, Issue 7, pp. 853-1016

Page 2 of 3 Pages Previous Page Next Page | Jump to Page
back to top
RSS Feeds

Piezoelectric-field-enhanced lateral ambipolar diffusion coefficient in InGaN/GaN multiple quantum wells

Yin-Chieh Huang, Jian-Chin Liang, Chi-Kuang Sun, Amber Abare, and Steven P. DenBaars

Appl. Phys. Lett. 78, 928 (2001); http://dx.doi.org/10.1063/1.1347399 (3 pages) | Cited 5 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Lateral diffusion behavior of two-dimensional carrier gas in InGaN/GaN multiple quantum wells was investigated using optical transient transmission measurements. A large ambipolar diffusion coefficient was observed, which was attributed to the enhancement by a strong piezoelectric field. This large ambipolar diffusion coefficient was found to increase with increased well width with a value on the order of 3000 cm2/s for a 62 Å well-width sample. © 2001 American Institute of Physics.
Show PACS
73.63.Hs Quantum wells
78.67.De Quantum wells
77.65.Ly Strain-induced piezoelectric fields
73.50.Dn Low-field transport and mobility; piezoresistance

Dynamic quantum-confined stark effect in self-assembled InAs quantum dots

M. Gurioli, S. Sanguinetti, and M. Henini

Appl. Phys. Lett. 78, 931 (2001); http://dx.doi.org/10.1063/1.1348305 (3 pages) | Cited 12 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We present a detailed investigation of the carrier dynamics in a set of InAs/GaAs (N11) quantum dots (QD) by means of time-resolved photoluminesce (PL) techniques. A dynamical red shift of the PL bands when increasing the delay time after the pulse excitation is observed. We attribute this intrinsic optical nonlinearity to the photoinduced screening of internal built-in electric field. The value of the redshift of the QD emission band decays with the carrier population demonstrating the intrinsic nature of the built-in field. Its dependence on the substrate orientation and termination agrees with the expected piezoelectric induced quantum confined Stark effects of the QD optical transitions. © 2001 American Institute of Physics.
Show PACS
78.20.Jq Electro-optical effects
78.55.Cr III-V semiconductors
78.66.Fd III-V semiconductors
78.67.Hc Quantum dots
78.47.-p Spectroscopy of solid state dynamics

Ultralarge capacitance–voltage hysteresis and charge retention characteristics in metal oxide semiconductor structure containing nanocrystals deposited by ion-beam-assisted electron beam deposition

Yong Kim, Kyung Hwa Park, Tae Hun Chung, Hong Jun Bark, Jae-Yel Yi, Won Chel Choi, Eun Kyu Kim, Ju Wook Lee, and Jeong Yong Lee

Appl. Phys. Lett. 78, 934 (2001); http://dx.doi.org/10.1063/1.1337618 (3 pages) | Cited 29 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Amorphous silicon films are deposited by ion-beam-assisted electron beam deposition and subsequently oxidized by a rapid thermal oxidation process. The oxidized film contains a large density of nanocrystals specifically localized at a certain depth from the Si/SiOx interface, whereas no evidence of nanocrystals is found for oxidized films deposited without ion beam assistance. Such a marked contrast resulted from the enhancement of nucleation rate by ion beam irradiation. The metal-oxide-semiconductor structure utilizing the film shows an ultralarge capacitance–voltage hysteresis whose width is over 20 V. In addition capacitance–time measurement shows a characteristic capacitance transient indicating nondispersive carrier relaxation. The retention time shows a dependence on applied bias and the maximum time of ∼70 s is obtained near midgap voltage. The retention time dependence on applied bias and large capacitance–voltage hysteresis are attributed to direct tunneling of trapped charges in the deep traps of nanocrystals to the interface states. © 2001 American Institute of Physics.
Show PACS
73.40.Qv Metal-insulator-semiconductor structures (including semiconductor-to-insulator)
81.15.-z Methods of deposition of films and coatings; film growth and epitaxy
73.22.-f Electronic structure of nanoscale materials and related systems
81.65.Mq Oxidation
81.15.Jj Ion and electron beam-assisted deposition; ion plating
61.80.Jh Ion radiation effects
81.07.Bc Nanocrystalline materials
73.20.Hb Impurity and defect levels; energy states of adsorbed species
73.50.Gr Charge carriers: generation, recombination, lifetime, trapping, mean free paths

Infrared response of multiple-component free-carrier plasma in heavily doped p-type GaAs

S. Zangooie, M. Schubert, D. W. Thompson, and J. A. Woollam

Appl. Phys. Lett. 78, 937 (2001); http://dx.doi.org/10.1063/1.1343490 (3 pages) | Cited 4 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Spectroscopic ellipsometry is used to measure the dielectric function of heavily doped p-type GaAs for wave numbers from 100 to 2000 cm−1. Due to partial filling of the heavy- and light-hole valence bands, heavy holes as well as light holes form a multiple-component plasma coupled with longitudinal optical phonons. Line-shape analysis of the infrared response allows differentiating between light- and heavy-hole contributions to the carrier plasma, and the results observed suggest nonparabolicity effects of the heavy- and light-hole valence bands in GaAs. © 2001 American Institute of Physics.
Show PACS
78.30.Fs III-V and II-VI semiconductors
71.45.Gm Exchange, correlation, dielectric and magnetic response functions, plasmons
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
63.20.-e Phonons in crystal lattices

Atomistic simulations of extrinsic defects evolution and transient enhanced diffusion in silicon

B. Colombeau, F. Cristiano, A. Altibelli, C. Bonafos, G. Ben Assayag, and A. Claverie

Appl. Phys. Lett. 78, 940 (2001); http://dx.doi.org/10.1063/1.1344566 (3 pages) | Cited 13 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
In this letter, a physically based model describing the kinetic evolution of extrinsic defects during annealing is presented. The fundamental concepts of Ostwald ripening and formation energy of extrinsic defects are combined in this model, which has been tested against some classical experiments concerning (i) transient enhanced diffusion (TED) of dopants in conjunction with the dissolution of {113} defects and (ii) the “pulsed” TED observed in the case of ultralow energy implants where the surface acts as a strong sink for the silicon interstitial atoms. We show that a full understanding of the formation and the evolution of extended defects leads to a correct prediction of dopant enhanced diffusion in all experimental conditions. © 2001 American Institute of Physics.
Show PACS
66.30.Dn Theory of diffusion and ionic conduction in solids
81.05.Cy Elemental semiconductors
66.30.Lw Diffusion of other defects
61.72.Cc Kinetics of defect formation and annealing
81.40.Gh Other heat and thermomechanical treatments
61.72.J- Point defects and defect clusters

Electrical isolation of GaN by MeV ion irradiation

H. Boudinov, S. O. Kucheyev, J. S. Williams, C. Jagadish, and G. Li

Appl. Phys. Lett. 78, 943 (2001); http://dx.doi.org/10.1063/1.1348306 (3 pages) | Cited 13 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The evolution of sheet resistance of n-type GaN epilayers exposed to irradiation with MeV H, Li, C, and O ions is studied in situ. Results show that the threshold dose necessary for complete isolation linearly depends on the original free electron concentration and reciprocally depends on the number of atomic displacements produced by ion irradiation. Furthermore, such isolation is stable to rapid thermal annealing at temperatures up to 900 °C. In addition to providing a better understanding of the physical mechanisms responsible for electrical isolation, these results can be used for choosing implant conditions necessary for an effective electrical isolation of GaN-based devices. © 2001 American Institute of Physics.
Show PACS
73.61.Ey III-V semiconductors
61.72.Cc Kinetics of defect formation and annealing
61.80.Jh Ion radiation effects

Operation of a three-junction single-electron pump with on-chip resistors

S. V. Lotkhov, S. A. Bogoslovsky, A. B. Zorin, and J. Niemeyer

Appl. Phys. Lett. 78, 946 (2001); http://dx.doi.org/10.1063/1.1347017 (3 pages) | Cited 40 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report on the operation of a single-electron pump (comprising three Al/AlOx/Al tunnel junctions and two gates) connected to the bias electrodes through the compact on-chip Cr resistors, R ≈ 60 kΩ>Rk = h/e2 ≈ 26 kΩ. The function of the resistors in this so-called R pump was to suppress electron cotunneling, the process which otherwise severely deteriorates the performance of few-junction single-electron devices. When a harmonic ac drive of frequency f of several MHz was applied to the gates, the current–voltage curve of the R pump exhibited remarkably horizontal current steps at I = ef. We show that the use of the resistors is capable of substantially increasing the accuracy of the pump in comparison to operation of the pump without resistors. © 2001 American Institute of Physics.
Show PACS
85.25.Am Superconducting device characterization, design, and modeling
85.35.Gv Single electron devices

Hole-trapping-related transients in shallow n+–p junctions fabricated in a high-energy boron-implanted p well

A. Poyai, E. Simoen, and C. Claeys

Appl. Phys. Lett. 78, 949 (2001); http://dx.doi.org/10.1063/1.1342041 (3 pages) | Cited 3 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
This letter describes a transient phenomenon in the reverse hole current of large-area shallow n+–p-well junctions, giving rise to a hump at a specific reverse bias. This corresponds to a certain depletion depth in the retrograde p well, which has been fabricated by a deep (200 keV) and a shallow (55 keV) boron ion implantation. No such a reverse hole current hump occurs for reference diodes, processed in p-type Czochralski substrates. The effect is also absent in large-perimeter p-well junctions, suggesting a correlation with defects in the p-well region. The occurrence at a specific depletion depth indicates a nonuniform defect distribution, for example related to the displacement damage created by the 200 keV B implantation. This idea is further supported by deep level transient spectroscopy results, which reveal the presence of a nonuniform density of hole traps, corresponding to a broad range of energy levels from about 0.3 to 0.5 eV above the valence band. A discussion of the possible nature of the underlying defects is given. © 2001 American Institute of Physics.
Show PACS
73.40.Lq Other semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
61.72.uf Ge and Si
85.30.Kk Junction diodes
73.50.Gr Charge carriers: generation, recombination, lifetime, trapping, mean free paths
73.63.Hs Quantum wells

Correlation of defect profiles with carrier profiles of InAs epilayers on GaP

H. Tsukamoto, E.-H. Chen, J. M. Woodall, and V. Gopal

Appl. Phys. Lett. 78, 952 (2001); http://dx.doi.org/10.1063/1.1338956 (3 pages) | Cited 1 time

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The carrier profile for InAs films grown on GaP is modeled as a first-order approximation which assumes that 90° edge dislocation intersections and the threading dislocation intersections act as shallow donors. Due to dislocation annihilation during growth, the threading dislocation intersection density decreases as the inverse of the distance x from the InAs/GaP interface, D(x) = D0x0/(x0+x), where D0 and x0 are dislocation density at the InAs/GaP interface and the first annihilation position from the interface, respectively. The carrier profile in InAs films can be described by a similar equation that is deduced from the threading dislocation intersection profile. The calculated carrier profiles agree well with measured carrier profiles. This correlation supports our hypothesis that both the edge dislocation intersections and the threading dislocation intersections act as shallow donor sources. © 2001 American Institute of Physics.
Show PACS
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
73.61.Ey III-V semiconductors
71.55.Eq III-V semiconductors
68.35.Dv Composition, segregation; defects and impurities
73.20.Hb Impurity and defect levels; energy states of adsorbed species
61.72.Ff Direct observation of dislocations and other defects (etch pits, decoration, electron microscopy, x-ray topography, etc.)
back to top
RSS Feeds

Transport and noise characteristics of submicron high-temperature superconductor grain-boundary junctions

F. Herbstritt, T. Kemen, L. Alff, A. Marx, and R. Gross

Appl. Phys. Lett. 78, 955 (2001); http://dx.doi.org/10.1063/1.1343847 (3 pages) | Cited 17 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We have investigated the transport and noise properties of submicron YBa2Cu3O7−δ bicrystal grain-boundary junctions prepared using electron beam lithography. The junctions show an increased conductance for low voltages reminiscent of Josephson junctions having a barrier with high transmissivity. The voltage noise spectra are dominated by a few Lorentzian components. At low temperatures clear two-level random telegraph switching signals are observable in the voltage versus time traces. We have investigated the temperature and voltage dependence of individual fluctuators both from statistical analysis of voltage versus time traces and from fits to noise spectra. A transition from tunneling to thermally activated behavior of individual fluctuators was clearly observed. The experimental results support the model of charge carrier traps in the barrier region. © 2001 American Institute of Physics.
Show PACS
74.50.+r Tunneling phenomena; Josephson effects
74.72.-h Cuprate superconductors
61.72.Mm Grain and twin boundaries
74.40.-n Fluctuation phenomena
85.25.Cp Josephson devices

Magnetic properties of Mn-doped ZnO

T. Fukumura, Zhengwu Jin, M. Kawasaki, T. Shono, T. Hasegawa, S. Koshihara, and H. Koinuma

Appl. Phys. Lett. 78, 958 (2001); http://dx.doi.org/10.1063/1.1348323 (3 pages) | Cited 284 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report on the magnetic properties of an oxide-diluted magnetic semiconductor (DMS), Zn0.64Mn0.36O. The temperature dependence of the magnetization shows a spin-glass behavior with the large magnitude of the Curie–Weiss temperature, corresponding to a stronger antiferromagnetic exchange coupling than other II–VI DMSs. The small effective Mn moment (math ∼ 0.02) under high field also represents a strong antiferromagnetic exchange coupling in this compound. © 2001 American Institute of Physics.
Show PACS
75.50.Pp Magnetic semiconductors
75.50.Ee Antiferromagnetics
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
75.40.-s Critical-point effects, specific heats, short-range order
75.50.Lk Spin glasses and other random magnets
75.30.Et Exchange and superexchange interactions
75.30.Cr Saturation moments and magnetic susceptibilities

Ultrathin epitaxial Fe films on vicinal GaAs(001): A study by spin-resolved photoelectron spectroscopy

T. Zhang, M. Spangenberg, D. Greig, N. Takahashi, T.-H. Shen, J. A. D. Matthew, S. Cornelius, M. Rendall, and E. A. Seddon

Appl. Phys. Lett. 78, 961 (2001); http://dx.doi.org/10.1063/1.1345820 (3 pages) | Cited 1 time

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Thin epitaxial Fe films have been grown on vicinal GaAs(001) substrates and their remanent magnetic properties and the degree of substrate atom diffusion investigated using synchrotron-based photoelectron spectroscopy. The vicinal Fe films, though exhibiting greater As diffusion than their singular homologues, displayed better film quality both from the structural and the magnetic points of view. The spin-resolved valence spectra of the vicinal films resemble those for crystalline bulk Fe at lower film thicknesses than for singular films. © 2001 American Institute of Physics.
Show PACS
79.60.Dp Adsorbed layers and thin films
75.50.Bb Fe and its alloys
75.70.Ak Magnetic properties of monolayers and thin films
71.20.Be Transition metals and alloys
68.55.-a Thin film structure and morphology

Negative coercivity in epitaxially grown (110) DyFe2/YFe2 superlattices

J-M. L. Beaujour, S. N. Gordeev, G. J. Bowden, P. A. J. de Groot, B. D. Rainford, R. C. C. Ward, and M. R. Wells

Appl. Phys. Lett. 78, 964 (2001); http://dx.doi.org/10.1063/1.1344594 (3 pages) | Cited 19 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Molecular beam epitaxial methods have been used to grow single crystal Laves phase DyFe2/YFe2 superlattice samples with a (110) growth direction. Detailed magnetization curves have been obtained for YFe2 dominated multilayer samples [wDyFe2/4wYFe2]×16 with w = 45, 50, and 55 Å. In particular, it is shown that the formation of magnetic exchange springs in the magnetically soft YFe2 layers, can be used to engineer multilayer samples with a negative coercivity. Further, by using asymmetric field cycling procedures, we have investigated the irreversible parts of the M–B loop, associated with the switching of the DyFe2 multilayers. © 2001 American Institute of Physics.
Show PACS
75.70.Cn Magnetic properties of interfaces (multilayers, superlattices, heterostructures)
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
75.30.Et Exchange and superexchange interactions
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
75.60.Jk Magnetization reversal mechanisms
75.50.Bb Fe and its alloys
75.50.Ee Antiferromagnetics

Superconducting quantum interference device as a near-quantum-limited amplifier at 0.5 GHz

Michael Mück, J. B. Kycia, and John Clarke

Appl. Phys. Lett. 78, 967 (2001); http://dx.doi.org/10.1063/1.1347384 (3 pages) | Cited 58 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A dc superconducting quantum interference device (SQUID) with a resonant microstrip input is operated as an amplifier at temperatures down to 20 mK. A second SQUID is used as a postamplifier. Below about 100 mK, the noise temperature is 52±20 mK at 538 MHz, estimated from measurements of signal-to-noise ratio, and 47±10 mK at 519 MHz, estimated from the noise generated by a resonant circuit coupled to the input. The quantum-limited noise temperatures are 26 and 25 mK, respectively. The measured noise temperature is limited by hot electrons generated by the bias current. © 2001 American Institute of Physics.
Show PACS
85.25.Dq Superconducting quantum interference devices (SQUIDs)
84.30.Le Amplifiers

Self-generation of bright microwave magnetic envelope soliton trains in ferrite films through frequency filtering

Mark M. Scott, Boris A. Kalinikos, and Carl E. Patton

Appl. Phys. Lett. 78, 970 (2001); http://dx.doi.org/10.1063/1.1347401 (3 pages) | Cited 19 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Resonant ring feedback with frequency filtering has been used for the self-generation of bright soliton trains. The solitons were produced from magnetostatic backward volume spin waves propagated in an in-plane magnetized magnetic film delay line as part of the resonant ring structure. The amplitude and phase time profiles, together with the power spectra of the self-generated pulses, confirm their bright soliton nature. © 2001 American Institute of Physics.
Show PACS
75.30.Ds Spin waves
75.50.Gg Ferrimagnetics
85.70.Ge Ferrite and garnet devices
75.40.Gb Dynamic properties (dynamic susceptibility, spin waves, spin diffusion, dynamic scaling, etc.)
05.45.Yv Solitons
85.70.Ec Magnetostrictive, magnetoacoustic, and magnetostatic devices
75.70.Ak Magnetic properties of monolayers and thin films
back to top
RSS Feeds

High-resolution electron microscopy investigations on stacking faults in SrBi2Ta2O9 ferroelectric thin films

X. H. Zhu, A. D. Li, D. Wu, T. Zhu, Z. G. Liu, and N. B. Ming

Appl. Phys. Lett. 78, 973 (2001); http://dx.doi.org/10.1063/1.1332106 (3 pages) | Cited 7 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Structural planar defects in the SrBi2Ta2O9 (SBT) films with 10 mol % excess Bi grown in Pt/TiO2/SiO2/Si substrates by metalorganic deposition have been observed by high-resolution electron microscopy. It was found that these stacking defects were planar defects with extra Bi–O planes normal to the c axis. These structural defects are expected to effectively improve the ferroelectric response and fatigue-resistance characteristics of SBT films because of the extra Bi–O planes having higher strucutral flexibility and alleviating the mechanical stresses and strains as well as injected-charge problems. © 2001 American Institute of Physics.
Show PACS
77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
61.72.Ff Direct observation of dislocations and other defects (etch pits, decoration, electron microscopy, x-ray topography, etc.)
61.72.Nn Stacking faults and other planar or extended defects

Langasite for high-temperature bulk acoustic wave applications

H. Fritze and H. L. Tuller

Appl. Phys. Lett. 78, 976 (2001); http://dx.doi.org/10.1063/1.1345797 (2 pages) | Cited 40 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Langasite (La3Ga5SiO14) and related compounds are promising candidates for high-temperature piezoelectric applications. To determine the stable operation of langasite as a high-temperature bulk acoustic wave (BAW) resonator, we characterized electrical conductivity [σel = 1.56×exp(−1.07 eV/kT)S/cm] and oxygen diffusivity [DoxT = 5×10−5 exp(−1.45 eV/kT)cm2/s] up to elevated temperatures. Langasite was successfully operated up to 900 °C as a BAW resonator with an average mass sensitivity of about 0.17 μg Hz−1 cm−2. This enables, in principle, high-temperature monitoring of deposition rates and thermogravimetry with high sensitivity. © 2001 American Institute of Physics.
Show PACS
77.65.Fs Electromechanical resonance; quartz resonators
85.50.-n Dielectric, ferroelectric, and piezoelectric devices
back to top
RSS Feeds

CNx/carbon nanotube junctions synthesized by microwave chemical vapor deposition

Xucun Ma and E. G. Wang

Appl. Phys. Lett. 78, 978 (2001); http://dx.doi.org/10.1063/1.1348319 (3 pages) | Cited 49 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The CNx/carbon nanotube junctions were successfully synthesized by microwave plasma-assisted chemical vapor deposition method from the mixture of N2/CH4 and H2/CH4 gases in a continuous growth process. High resolution transmission electron microscopy revealed that these junctions were of heterostructure between CNx nanotubes with polymerized nanobells and cylindrical carbon nanotubes. The growth process is quite simple and can be easily scaled up. The intimate correlation between the electronic structure and the chemical composition at the both sides of the junction indicate some interesting properties and offers potential applications for future nanodevices. © 2001 American Institute of Physics.
Show PACS
61.48.-c Structure of fullerenes and related hollow and planar molecular structures
61.46.-w Structure of nanoscale materials
81.05.ub Fullerenes and related materials
81.07.De Nanotubes
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
73.20.At Surface states, band structure, electron density of states
71.20.Tx Fullerenes and related materials; intercalation compounds

Deep submicron microcontact printing on planar and curved substrates utilizing focused ion beam fabricated printheads

D. M. Longo, W. E. Benson, T. Chraska, and R. Hull

Appl. Phys. Lett. 78, 981 (2001); http://dx.doi.org/10.1063/1.1348308 (3 pages) | Cited 18 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Focused ion beam (FIB) fabrication of nanostructured “printheads” is used to extend applications of microcontact printing. Planar and curved printheads are fabricated with feature sizes less than 100 nm over fields of view of order 1 mm2, and transferred to target substrates with spatial resolution of order 200 nm. Analysis of the mechanical and ion optical stabilities of the FIB demonstrates that several hours of printhead fabrication time are possible with nanoscale precision. The rapid prototyping capability of this approach and the large depth of focus in the FIB enable rapid nanoscale patterning of a wide range of surface geometries. © 2001 American Institute of Physics.
Show PACS
81.16.-c Methods of micro- and nanofabrication and processing
85.35.-p Nanoelectronic devices

Spatial ordering of stacked quantum dots

C.-S. Lee, B. Kahng, and A.-L. Barabási

Appl. Phys. Lett. 78, 984 (2001); http://dx.doi.org/10.1063/1.1347391 (3 pages) | Cited 17 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We investigate the growth conditions necessary to form an ordered quantum dot crystal by capping spatially ordered quantum dots and growing a new layer of dots on top of the capping layer. Performing Monte Carlo simulations and developing analytic arguments based on the stress energy function, we demonstrate the existence of an optimal capping layer thickness, external flux, and temperature for the formation of quantum dot crystals. © 2001 American Institute of Physics.
Show PACS
68.65.Hb Quantum dots (patterned in quantum wells)
81.07.Ta Quantum dots

Resonant Raman scattering on self-assembled GaN quantum dots

M. Kuball, J. Gleize, Satoru Tanaka, and Yoshinobu Aoyagi

Appl. Phys. Lett. 78, 987 (2001); http://dx.doi.org/10.1063/1.1347386 (3 pages) | Cited 13 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Self-assembled GaN quantum dots grown on Al0.15Ga0.85N using Si as antisurfactant have been investigated by resonant Raman scattering. Phonons of GaN quantum dots of different sizes and the Al0.15Ga0.85N barrier layer were probed selectively by varying the laser excitation energy from 3.53 to 5.08 eV. Phonon confinement effects were studied on GaN quantum dots of 2–3 nm height. We show that although grown using Si (a common donor for GaN) as an antisurfactant, only a small electron concentration is present in the GaN quantum dots. Implications on the role of Si for the formation of the GaN quantum dots will be discussed. © 2001 American Institute of Physics.
Show PACS
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

Writing and reading perpendicular magnetic recording media patterned by a focused ion beam

J. Lohau, A. Moser, C. T. Rettner, M. E. Best, and B. D. Terris

Appl. Phys. Lett. 78, 990 (2001); http://dx.doi.org/10.1063/1.1347390 (3 pages) | Cited 67 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We have written and read bit patterns on arrays of square islands cut with a focused ion beam into granular perpendicular magnetic recording media. Using a static write–read tester, we have written square-wave bit patterns on arrays of islands with sizes between 60 and 230 nm, matching the recording linear density to the pattern period. These measurements reveal the onset of single-domain behavior for islands smaller than 130 nm, in agreement with magnetic force microscope images. The recording performance of patterned regions is systematically compared to that of unpatterned regions. © 2001 American Institute of Physics.
Show PACS
75.50.Ss Magnetic recording materials
85.70.Kh Magnetic thin film devices: magnetic heads (magnetoresistive, inductive, etc.); domain-motion devices, etc.
75.50.Cc Other ferromagnetic metals and alloys
75.70.Kw Domain structure (including magnetic bubbles and vortices)
68.37.Rt Magnetic force microscopy (MFM)
75.60.Ch Domain walls and domain structure
68.37.Ps Atomic force microscopy (AFM)
back to top
RSS Feeds

Potentiometry of an operating organic semiconductor field-effect transistor

Kannan Seshadri and C. Daniel Frisbie

Appl. Phys. Lett. 78, 993 (2001); http://dx.doi.org/10.1063/1.1345805 (3 pages) | Cited 81 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The potential profile across the channel of an operating sexithiophene-based field-effect transistor (FET) was investigated using an atomic force microscope with a conducting probe. A high impedance electrometer recorded the probe potential when it was placed in contact at fixed points with the channel surface. Tapping mode images taken with the same probe before and after individual point contact measurements verified that no damage was done to the device and allowed correlation of the potential profile with the device architecture. For any given source-drain bias, most of the potential drop occurred at the source and drain contacts, meaning the FET was contact limited. Moreover, the potential drop was not fixed but depended on the applied drain and gate voltages. This study demonstrates the utility of potential profiling for identifying high resistance bottlenecks to charge transport in organic-based devices. © 2001 American Institute of Physics.
Show PACS
85.30.Tv Field effect devices
68.37.Ps Atomic force microscopy (AFM)
back to top
RSS Feeds

Dielectric spectroscopy for bioanalysis: From 40 Hz to 26.5 GHz in a microfabricated wave guide

G. R. Facer, D. A. Notterman, and L. L. Sohn

Appl. Phys. Lett. 78, 996 (2001); http://dx.doi.org/10.1063/1.1347020 (3 pages) | Cited 37 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report developing coplanar waveguide devices which can perform dielectric spectroscopy on biological samples within a microfluidic channel or well. Since coupling to the fluid sample is capacitive, no surface functionalization or chemical sample preparation are required. Data on cell suspensions and solutions of proteins and nucleic acids spanning the frequency range from 40 Hz to 26.5 GHz are presented. Low-frequency data are well explained using a simple dispersion model. At microwave frequencies, the devices yield reproducible and distinguishable spectral responses for hemoglobin solution and live E. coli. © 2001 American Institute of Physics.
Show PACS
87.64.-t Spectroscopic and microscopic techniques in biophysics and medical physics
84.40.Az Waveguides, transmission lines, striplines
47.85.Np Fluidics
87.17.-d Cell processes
87.15.M- Spectra of biomolecules
87.14.E- Proteins
82.39.Pj Nucleic acids, DNA and RNA bases
82.70.Kj Emulsions and suspensions

Three-dimensional subsurface microprocessing of collagen by ultrashort laser pulses

Nicholas I. Smith, Katsumasa Fujita, Osamu Nakamura, and Satoshi Kawata

Appl. Phys. Lett. 78, 999 (2001); http://dx.doi.org/10.1063/1.1347392 (3 pages) | Cited 7 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Submicron sized damage spots were created by multiphoton absorption of ultrashort 775 nm laser pulses in collagen gel stained with fluorescent dye. Submicron nodules were formed in the collagen both near the surface and at a depth of up to 30 μm. We have shown that large numbers of pulses at low pulse energy provide well-controlled sample damage restricted to a small focal volume. The damage threshold was dependent on dye concentration but not significantly dependent on the depth. This will be useful for experiments that study laser-induced damage in living biological samples on a cellular scale and deep within the specimen. © 2001 American Institute of Physics.
Show PACS
87.50.W- Optical/infrared radiation effects
87.14.E- Proteins
87.17.-d Cell processes
Page 2 of 3 Pages Previous Page Next Page | Jump to Page
Close

Google Calendar

ADVERTISEMENT

Go to AIP Home   © AIP Publishing LLC
close