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

21 Oct 1996

Volume 69, Issue 17, pp. 2453-2609

Page 2 of 3 Pages Previous Page Next Page | Jump to Page

Hot‐electron power loss in a doped GaAs/AlGaAs superlattice at intermediate temperature studied by infrared differential spectroscopy

W. Hilber, M. Helm, K. Alavi, and R. N. Pathak

Appl. Phys. Lett. 69, 2528 (1996); http://dx.doi.org/10.1063/1.117728 (3 pages) | Cited 6 times

Full Text: | Download PDF

Show Abstract
The power loss of electrons in a strongly coupled n‐type GaAs/AlxGa1−xAs superlattice is studied by analyzing the temperature and electric‐field dependence of the interminiband absorption. Electrons are heated by an electric‐field pulse and the resulting change of the infrared absorption spectrum is monitored by a step‐scan Fourier transform spectrometer operated in a time‐resolved, gated mode. The measured power loss is higher than predicted by a simple three‐dimensional calculation including acoustic (deformation potential and piezoelectric) and polar‐optical phonon emission. Possible explanations for this, such as relaxation via folded acoustic phonons or coupled plasmon–phonon modes, are discussed. The energy relaxation time, which can be extracted from the power balance, decreases from 300 ps at 15 K to 20 ps at 48 K. © 1996 American Institute of Physics.
Show PACS
73.50.Fq High-field and nonlinear effects
73.61.Ey III-V semiconductors
78.30.Fs III-V and II-VI semiconductors

Electron beam induced current measurements of minority carrier diffusion length in gallium nitride

Leonid Chernyak, Andrei Osinsky, Henryk Temkin, J. W. Yang, Q. Chen, and M. Asif Khan

Appl. Phys. Lett. 69, 2531 (1996); http://dx.doi.org/10.1063/1.117729 (3 pages) | Cited 60 times

Full Text: | Download PDF

Show Abstract
Minority carrier diffusion length in epitaxial GaN layers was measured as a function of majority carrier concentration and temperature. The diffusion length of holes in n‐type GaN is found to decrease from 3.4 to 1.2 μm in the doping range of 5×1015–2×1018 cm−3. The experimental results can be fitted by assuming the Einstein relation and by the experimental dependence of hole mobilities on carrier concentration. The low injection carrier lifetime of ∼15 ns, used in the fit, is largely independent of the doping level. The diffusion length, measured for ∼5×1015 and 2×1018 cm−3 dopant concentrations, shows an increase with increasing temperature, characterized by an activation energy Ea of ∼90 meV, independent of the impurity concentration. © 1996 American Institute of Physics.
Show PACS
73.61.Ey III-V semiconductors
73.50.Dn Low-field transport and mobility; piezoresistance
68.37.Hk Scanning electron microscopy (SEM) (including EBIC)
68.37.Lp Transmission electron microscopy (TEM)

Solid‐phase epitaxial growth of amorphized GaAs: The influence of macroscopic nonstoichiometry

K. B. Belay, D. J. Llewellyn, and M. C. Ridgway

Appl. Phys. Lett. 69, 2534 (1996); http://dx.doi.org/10.1063/1.117730 (3 pages) | Cited 3 times

Full Text: | Download PDF

Show Abstract
Defective recrystallization in the form of twins and stacking faults is characteristic of the solid‐phase epitaxial growth (SPEG) of amorphized GaAs at temperatures ∼<400 °C. For the present report, the influence of macroscopic nonstoichiometry on defect formation has been investigated by comparing the SPEG of Ga‐ and/or As‐implanted samples. The onset of twinning was independent of the chemical concentration of the implanted atom at the amorphous/crystalline interface, indicating that defective recrystallization was not the result of a limited availability of a given lattice constituent. Thereafter, a rapid amorphous‐to‐crystalline transformation was observed in the presence of excess Ga. In contrast, excess As had no significant effect on the recrystallization kinetics. Measurements derived from in situ transmission electron microscopy showed that the velocity of the amorphous/twinned interface was well correlated with the excess Ga concentration, the latter potentially in the form of molten precipitates. The rapid amorphous‐to‐crystalline transformation may thus be melt mediated although in addition nonstoichiometry could also result in a local increase in defect concentration particular to an enhanced twinned regrowth velocity. © 1996 American Institute of Physics.
Show PACS
68.55.-a Thin film structure and morphology
81.15.Np Solid phase epitaxy; growth from solid phases
61.72.Ff Direct observation of dislocations and other defects (etch pits, decoration, electron microscopy, x-ray topography, etc.)
61.66.Bi Elemental solids
61.66.Dk Alloys

Activation of luminescence in polycrystalline silicon thin films by ultrasound treatment

J. Koshka, S. Ostapenko, T. Ruf, and J. M. Zhang

Appl. Phys. Lett. 69, 2537 (1996); http://dx.doi.org/10.1063/1.117731 (3 pages) | Cited 8 times

Full Text: | Download PDF

Show Abstract
A dramatic increase of infrared photoluminescence (PL) intensity by a factor of 2 orders of magnitude is observed after a few minutes at 250 °C of ultrasound treatment (UST) applied to polycrystalline silicon thin films on glass substrates. In films obtained by solid‐phase crystallization of amorphous silicon at 550 °C, UST enhances the PL band intensity at 0.7 eV, and also activates a new luminescence maximum at about 0.9 eV. We prove that the 0.9 eV PL band is related to the amorphous fraction of poly‐Si films. Due to similarities in spectral shape and temperature behavior, this UST activated luminescence is attributed to a ‘‘defect’’ PL band previously observed in hydrogenated amorphous Si. This conclusion is confirmed by using a set of films with controlled fractions of the amorphous to crystalline phase. A mechanism of ultrasound stimulated hydrogen detrapping followed by hydrogen diffusion and passivation of nonradiative centers (e.g., dangling bonds) in polycrystalline and amorphous Si films is discussed. © 1996 American Institute of Physics.
Show PACS
78.55.Ap Elemental semiconductors
78.66.Db Elemental semiconductors and insulators
61.72.Yx Interaction between different crystal defects; gettering effect
81.40.Tv Optical and dielectric properties related to treatment conditions

Hysteresis relaxation in (Pb,La)(Zr,Ti)O3 thin film capacitors with (La,Sr)CoO3 electrodes

S. Aggarwal, A. M. Dhote, R. Ramesh, W. L. Warren, G. E. Pike, D. Dimos, M. V. Raymond, B. A. Tuttle, and J. T. Evans

Appl. Phys. Lett. 69, 2540 (1996); http://dx.doi.org/10.1063/1.117732 (3 pages) | Cited 31 times

Full Text: | Download PDF

Show Abstract
We report on the thermally activated hysteresis relaxation effects in (La,Sr)CoO3/ (Pb,La)(Zr,Ti)O3/(La,Sr)CoO3 thin film ferroelectric capacitors. Films cooled in oxygen deficient ambients exhibit a marked voltage offset in the hysteresis loops. Upon the application of a dc bias voltage or unidirectional pulses of the same polarity as the offset, the loops become more symmetric. Subsequently, holding the capacitors in the original preferred polarization state leads to a relaxation of the hysteresis loop towards its original voltage offset condition. The relaxation process is described by a stretched exponential and is thermally activated. © 1996 American Institute of Physics.
Show PACS
77.80.Dj Domain structure; hysteresis
77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates
85.50.-n Dielectric, ferroelectric, and piezoelectric devices

Trap signatures of As precipitates and As‐antisite‐related defects in GaAs epilayers grown by molecular beam epitaxy at low temperatures

C. H. Goo, W. S. Lau, T. C. Chong, and L. S. Tan

Appl. Phys. Lett. 69, 2543 (1996); http://dx.doi.org/10.1063/1.117733 (3 pages) | Cited 8 times

Full Text: | Download PDF

Show Abstract
Despite many separate studies of the two dominant defects, i.e., As precipitates and arsenic‐antisite (AsGa)‐related traps, in GaAs epilayers grown by molecular beam epitaxy at low temperatures, they are seldom examined simultaneously. In this letter, we report the detection of both defects in electron trap spectrum obtained by zero quiescent bias voltage transient current spectroscopy. The As precipitates appear as a broad continuum of states in the lower temperature region (<280 K) of the spectra whereas the AsGa‐related defect appears as a discrete peak at a higher temperature. The AsGa‐related trap has an activation energy of 0.65 eV and a capture cross section of 9.3×10−14 cm2. It is found that the trap characteristic of low temperature GaAs is strongly dependent on its growth temperature and the above mentioned defects may not dominate in some cases. © 1996 American Institute of Physics.
Show PACS
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
71.55.Eq III-V semiconductors
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy

Coherent islands as preferential sites for sticking of Ge atoms in Si/Ge multilayers: Formation of conical shaped defects

E. Carlino, L. Tapfer, and H. von Känel

Appl. Phys. Lett. 69, 2546 (1996); http://dx.doi.org/10.1063/1.117734 (3 pages) | Cited 3 times

Full Text: | Download PDF

Show Abstract
In this work we investigate the role of coherent islands in the strain relaxation mechanism of Si/SixGe1−x multilayers by using conventional transmission electron microscopy, high‐resolution transmission electron microscopy, and transmission electron spectroscopic imaging. The samples investigated were grown by molecular beam epitaxy and they differ in the number of periods, period thickness, and in the Si/Ge layer thickness ratio. The formation of defect free coherent islands in strained SixGe1−x layers is at the origin of the peculiar morphology of the interfaces (waviness). We show that coherent islands act as preferential sticking sites for Ge adatoms, producing regions of higher Ge concentration. The higher concentration of Ge corresponding to the greater lattice spacing on the top of the coherent islands depletes the relevant strained layers. The corresponding accumulation of strain energy produces the formation of ‘‘conical‐shaped defects.’’ Inside these conical‐shaped defects the elastic energy is relieved by nucleation of dislocations. © 1996 American Institute of Physics.
Show PACS
68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties
68.60.Bs Mechanical and acoustical properties
68.35.Fx Diffusion; interface formation
68.37.Hk Scanning electron microscopy (SEM) (including EBIC)
68.37.Lp Transmission electron microscopy (TEM)

Step‐free surface grown on GaAs (111)B substrate by selective area metalorganic vapor phase epitaxy

Toshio Nishida and Naoki Kobayashi

Appl. Phys. Lett. 69, 2549 (1996); http://dx.doi.org/10.1063/1.117735 (2 pages) | Cited 9 times

Full Text: | Download PDF

Show Abstract
Selective metalorganic vapor phase epitaxy of GaAs within a finite area was investigated on (111)B substrate. The surface stoichiometry is determined based on surface photo‐absorption measurement. High‐temperature growth at 800 °C on stable GaAs (111)B and a cooling procedure with the (2×2)‐like surface to improve flatness result in an intentionally step‐free surface with device dimensions as wide as 8 μm on a selectively grown GaAs mesa. © 1996 American Institute of Physics.
Show PACS
81.15.Kk Vapor phase epitaxy; growth from vapor phase
68.35.B- Structure of clean surfaces (and surface reconstruction)
61.66.Bi Elemental solids
61.66.Dk Alloys

Effect of low temperature postannealing on the hole density of C δ‐doped GaAs and Al0.3Ga0.7As

G. Li and C. Jagadish

Appl. Phys. Lett. 69, 2551 (1996); http://dx.doi.org/10.1063/1.117736 (3 pages) | Cited 3 times

Full Text: | Download PDF

Show Abstract
In C δ‐doped GaAs and Al0.3Ga0.7As grown by metalorganic vapor phase epitaxy using trimethylaluminium as a doping precursor, 20%–50% of the C acceptors are not electrically active due to hydrogen passivation. These hydrogen passivated C acceptors can be activated by low temperature postannealing in the N2 ambient. The amount of activated C acceptors depends on the postannealing temperature and postannealing time. After ∼10 min postannealing at 530 °C, most of hydrogen passivated C acceptors are activated, leading to a constant hole density with a further increase in postannealing time. At a given postannealing time of 15 min, an increased temperature always activates more hydrogen passivated C acceptors. There is no measurable change in the hole density after 15 min postannealing at temperatures below 450 °C. The activated C acceptors can be re‐passivated by heating the postannealed C δ‐doped (Al,Ga)As to 480 °C in the AsH3/H2 ambient but not in the H2 ambient. The as‐grown C δ‐doped GaAs with much less hydrogen passivation can be grown using the H2 cooling ambient. © 1996 American Institute of Physics.
Show PACS
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
71.55.Eq III-V semiconductors
72.80.Ey III-V and II-VI semiconductors

Interface roughness and alloy‐disorder scattering contributions to intersubband transition linewidths

K. L. Campman, H. Schmidt, A. Imamoglu, and A. C. Gossard

Appl. Phys. Lett. 69, 2554 (1996); http://dx.doi.org/10.1063/1.117737 (3 pages) | Cited 60 times

Full Text: | Download PDF

Show Abstract
We report measurements of intersubband absorption in single semiconductor quantum wells of different well widths and alloy compositions. The well width dependence of the intersubband absorption linewidth is consistent with broadening dominated by interface roughness. The linewidth, however, is found to be relatively unaffected by alloy composition in the quantum well, making alloying an effective tool in the design of quantum well optical devices relying on intersubband transitions. © 1996 American Institute of Physics.
Show PACS
78.66.Fd III-V semiconductors
78.30.Fs III-V and II-VI semiconductors
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy

Band gap of Ge rich Si1−x−yGexCy alloys

B. A. Orner, J. Olowolafe, K. Roe, J. Kolodzey, T. Laursen, J. W. Mayer, and J. Spear

Appl. Phys. Lett. 69, 2557 (1996); http://dx.doi.org/10.1063/1.117738 (3 pages) | Cited 14 times

Full Text: | Download PDF

Show Abstract
Si1−x−yGexCy films ( x≊0.90, y⩽0.02) were grown by molecular beam epitaxy on Si substrates. Infrared optical absorption was used to obtain the band gap energy at room temperature. Biaxial strain obtained from x‐ray diffraction measurements verified the presence of nearly relaxed films, and the total and substitutional C contents were obtained from channeling C‐resonance backscattering spectrometry. We show by direct measurements that interstitial C had a negligible impact on the band gap, but substitutional C was found to increase the band gap with respect to equivalently strained Si1−xGex alloys. While strain decreases the band gap, the effect of substitutional C on the band gap depends on the Si and Ge fractions. © 1996 American Institute of Physics.
Show PACS
78.66.Db Elemental semiconductors and insulators
73.61.Cw Elemental semiconductors
71.20.Nr Semiconductor compounds

Below threshold conduction in a‐Si:H thin film transistors with and without a silicon nitride passivating layer

H. C. Slade, M. S. Shur, S. C. Deane, and M. Hack

Appl. Phys. Lett. 69, 2560 (1996); http://dx.doi.org/10.1063/1.117739 (3 pages) | Cited 11 times

Full Text: | Download PDF

Show Abstract
We report temperature measurements of inverted staggered amorphous silicon thin film transistor subthreshold conductance for devices with and without a top silicon nitride passivating layer. Subthreshold conductance activation energies clearly show the different conductance paths in the active layer of these devices. Transistors with no top nitride layer conduct in the bulk amorphous silicon, whereas the devices with a top nitride layer conduct at the interface between the amorphous silicon and the top nitride (a ‘‘back’’ channel). Gate bias stressing and light soaking experiments uphold the existence of the back channel. We also present two‐dimensional simulations that support our interpretation of the experimental data. © 1996 American Institute of Physics.
Show PACS
85.30.Tv Field effect devices
85.30.De Semiconductor-device characterization, design, and modeling
73.61.Jc Amorphous semiconductors; glasses

Hall mobility analysis in low‐temperature‐grown molecular‐beam epitaxial GaAs

J. Betko, M. Morvic, J. Novák, A. Förster, and P. Kordos

Appl. Phys. Lett. 69, 2563 (1996); http://dx.doi.org/10.1063/1.117740 (3 pages) | Cited 18 times

Full Text: | Download PDF

Show Abstract
Temperature dependent conductivity and Hall effect measurements were carried out on molecular‐beam epitaxial GaAs layers grown at 200–420 °C and separated from the substrate. An analysis of experimental data with and without considering the hopping Hall mobility was made. An extremely low room temperature Hall mobility of 0.14 cm2 V−1 s−1 was measured in the 250 °C layer, which could be interpreted as the hopping Hall mobility. The room temperature band Hall mobility (μHb) increases from 500 to 6000 cm2 V−1 s−1 and the power (n) of the temperature dependence of μHb (∼T−n) increases from 0.5 to 1.2 with increasing growth temperature from 300 to 420 °C. © 1996 American Institute of Physics.
Show PACS
73.50.Dn Low-field transport and mobility; piezoresistance
73.61.Ey III-V semiconductors
72.20.My Galvanomagnetic and other magnetotransport effects

Ultrafast high‐intensity nonlinear absorption dynamics in low‐temperature grown gallium arsenide

U. Siegner, R. Fluck, G. Zhang, and U. Keller

Appl. Phys. Lett. 69, 2566 (1996); http://dx.doi.org/10.1063/1.117701 (3 pages) | Cited 51 times

Full Text: | Download PDF

Show Abstract
We study carrier dynamics in GaAs thin films grown by molecular beam epitaxy at 250, 300, and 350 °C by differential transmission experiments at various carrier excitation densities. The differential transmission shows that carrier trapping in point defects is much faster than the recombination of the trapped carriers. As a consequence, the defect states can be saturated at high carrier densities. If the growth temperature is decreased, the initial trapping becomes faster while the subsequent recombination of the trapped carriers becomes slower. We show that this is due to the growth temperature dependent defect densities. © 1996 American Institute of Physics.
Show PACS
78.47.-p Spectroscopy of solid state dynamics
71.55.Eq III-V semiconductors

High resistivity and ultrafast carrier lifetime in argon implanted GaAs

W. Walukiewicz, Z. Liliental‐Weber, J. Jasinski, M. Almonte, A. Prasad, E. E. Haller, E. R. Weber, P. Grenier, and J. F. Whitaker

Appl. Phys. Lett. 69, 2569 (1996); http://dx.doi.org/10.1063/1.117702 (3 pages) | Cited 5 times

Full Text: | Download PDF

Show Abstract
We have investigated the optoelectronic and structural properties of GaAs that has been implanted with Ar ions and subsequently annealed. The material exhibits all the basic optical and electronic characteristics typically observed in nonstoichiometric, As implanted or low‐temperature‐grown GaAs. Annealing of Ar implanted GaAs at 600 °C produces a highly resistive material with a subpicosecond trapping lifetime for photoexcited carriers. Transmission electron microscopy shows that, instead of As precipitates, characteristic for the nonstoichiometeric GaAs, voids ranging in size from 3 to 5 nm are observed in Ar implanted and annealed GaAs. © 1996 American Institute of Physics.
Show PACS
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping
61.72.uj III-V and II-VI semiconductors
71.55.Eq III-V semiconductors

Microstructural development and optical properties of epitaxial Ge1−xCx alloys on Si(100)

M. Krishnamurthy, Bi‐Ke Yang, and W. H. Weber

Appl. Phys. Lett. 69, 2572 (1996); http://dx.doi.org/10.1063/1.117703 (3 pages) | Cited 18 times

Full Text: | Download PDF

Show Abstract
We report on the microstructural development and optical properties of epitaxial Ge1−xCx alloys (0<x<0.1) grown on Si(100) by low‐temperature (200 °C) molecular‐beam epitaxy. Films with C concentrations below 2%–3% grow in 2D layers, while films with C higher than 5% form 3D islands after initial layer growth. X‐ray‐diffraction indicates that less than 1% C may have been substitutionally incorporated. Spectroscopic ellipsometry measurements of the films’ optical constants show small systematic changes with increasing C concentration. These changes occur primarily near 2 eV, the E1 critical point in Ge. No new features attributable to Ge–C vibrational modes could be identified using Raman spectroscopy. © 1996 American Institute of Physics.
Show PACS
68.55.-a Thin film structure and morphology
78.66.Db Elemental semiconductors and insulators

Conductance anomaly in a quantum well

Chang Sub Kim and Oleg Olendski

Appl. Phys. Lett. 69, 2575 (1996); http://dx.doi.org/10.1063/1.117704 (3 pages) | Cited 2 times

Full Text: | Download PDF

Show Abstract
A single quantum well under the influence of vertical electric and in‐plane magnetic fields is considered theoretically. Within an effective mass and independent‐electron approximation, the spectroscopy of energy levels and the lateral currents are obtained. We found an interesting anomaly in our calculations of transverse differential conductance which suggests the possibility of a novel field‐effect concept. © 1996 American Institute of Physics.
Show PACS
73.40.-c Electronic transport in interface structures
72.10.Bg General formulation of transport theory
73.50.Bk General theory, scattering mechanisms

Improvement of SiGe oxide grown by electron cyclotron resonance using H2O vapor annealing

D. Tchikatilov, Y. F. Yang, and E. S. Yang

Appl. Phys. Lett. 69, 2578 (1996); http://dx.doi.org/10.1063/1.117705 (3 pages) | Cited 16 times

Full Text: | Download PDF

Show Abstract
The influence of low‐temperature annealing in H2O vapor on electron‐cyclotron‐resonance (ECR) grown SiGe oxides is reported. Annealing the oxides in H2O vapor at 280 °C for 3 h 20 min, applied after annealing in forming gas at 450 °C for 30 min, has several important effects: It reduces oxide leakage current by up to four orders of magnitude, decreases the density of interface states, and results in a low fixed oxide charge density of −5.0×1010 cm−2 in comparison to those of the films subjected to annealing in forming gas only. In addition, higher cumulative dielectric breakdown fields up to 8 MV/cm have been achieved. From the results obtained it is evident that vapor annealing is beneficial for ECR‐grown SiGe oxides. © 1996 American Institute of Physics.
Show PACS
77.55.-g Dielectric thin films
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)

Far‐infrared ellipsometry of depleted surface layer in heavily doped n‐type GaAs

J. Humlíček, R. Henn, and M. Cardona

Appl. Phys. Lett. 69, 2581 (1996); http://dx.doi.org/10.1063/1.117706 (3 pages) | Cited 15 times

Full Text: | Download PDF

Show Abstract
Far‐infrared ellipsometric spectra of n‐type (100) GaAs display sharp features in the range of the longitudinal optical phonon of intrinsic material, originating in the surface depletion region. We compare measured relative ellipsometric phase shifts with model calculations of the graded depletion layer. A very good agreement is observed, enabling us to determine the surface potential. © 1996 American Institute of Physics.
Show PACS
73.25.+i Surface conductivity and carrier phenomena
07.60.Fs Polarimeters and ellipsometers
78.30.Fs III-V and II-VI semiconductors
78.66.Fd III-V semiconductors

Synthesis of InP‐based 1.3 μm band gap pseudoalloy by organometallic vapor phase epitaxy

D. T. Emerson and J. R. Shealy

Appl. Phys. Lett. 69, 2584 (1996); http://dx.doi.org/10.1063/1.117707 (3 pages) | Cited 1 time

Full Text: | Download PDF

Show Abstract
Synthesis of short period GaInAs/InP superlattices, or pseudoalloys, by organometallic vapor phase epitaxy for replacement of the mixed crystal GaInAsP deposited on InP is discussed. Raman scattering, double crystal x‐ray diffraction, photoluminescence, and atomic force microscopy are used to investigate accumulative interface roughening and layer intermixing in the pseudoalloy. We demonstrate that pseudoalloy quality is not necessarily comprised by the presence of unintentional interfacial layers and show that thick (>2500 Å) InP‐based pseudoalloys with structural and optical properties that compare favorably with those of the random alloy can be synthesized. Finally, we present results on broad area 1.3 μm lasers incorporating the pseudoalloy as the optical gain media in separate confinement heterostructure devices. © 1996 American Institute of Physics.
Show PACS
68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties
81.15.Kk Vapor phase epitaxy; growth from vapor phase
68.35.Ct Interface structure and roughness
85.60.Jb Light-emitting devices

Determining band offsets using surface photovoltage spectroscopy: The InP/In0.53Ga0.47As heterojunction

M. Leibovitch, L. Kronik, B. Mishori, Yoram Shapira, C. M. Hanson, A. R. Clawson, and Prakhya Ram

Appl. Phys. Lett. 69, 2587 (1996); http://dx.doi.org/10.1063/1.117708 (3 pages) | Cited 10 times

Full Text: | Download PDF

Show Abstract
A direct technique for determining band offsets at semiconductor heterojunctions is presented, which is applicable to at least any type I heterojunction, where the top layer doping is sufficiently low. The technique is based on surface photovoltage spectroscopy measurements as a function of overlayer thickness. A numerically simulated example shows that the band offset is a very strong function of the critical overlayer thickness, at which the overlayer contribution to the surface photovoltage spectrum appears. The method is applied to the technologically important InP/InGaAs heterojunction and is shown to yield the commonly accepted band offset value. © 1996 American Institute of Physics.
Show PACS
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems
73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
73.25.+i Surface conductivity and carrier phenomena

Thin‐film YBa2Cu3O7−x direct current SQUIDs with Josephson junctions made by direct electron beam writing

B. Nadgorny, S. Shokhor, M. Gurvitch, S. Y. Hou, and Julia M. Phillips

Appl. Phys. Lett. 69, 2590 (1996); http://dx.doi.org/10.1063/1.117709 (3 pages)

Full Text: | Download PDF

Show Abstract
We have investigated dc superconducting quantum interference devices (SQUIDs) with loop areas 8 and 64 μm2 made by direct electron beam writing in YBa2Cu3O7−x films with thickness 25 and 50 nm. The SQUIDs have maximum peak‐to‐peak voltage modulation of about 20 μV, which corresponds to the transfer factor dV/dΦ0∼50–60 μV/Φ0 at 30–40 K. By measuring the mutual inductance of the SQUID signal line as a function of temperature and comparing the data with the numerical calculations and the two‐fluid model, we extracted the values of the London penetration depth for YBa2Cu3O7−x thin films. © 1996 American Institute of Physics.
Show PACS
74.78.-w Superconducting films and low-dimensional structures
85.25.Dq Superconducting quantum interference devices (SQUIDs)

Charge sensitivity of superconducting single‐electron transistor

Alexander N. Korotkov

Appl. Phys. Lett. 69, 2593 (1996); http://dx.doi.org/10.1063/1.117710 (3 pages) | Cited 20 times

Full Text: | Download PDF

Show Abstract
It is shown that the noise‐limited charge sensitivity of a single‐electron transistor using superconductors (of either SISIS‐ or NISIN‐type) operating near the threshold of quasiparticle tunneling, can be considerably higher than that of a similar transistor made of normal metals or semiconductors. The reason is that the superconducting energy gap, in contrast to the Coulomb blockade, is not smeared by the finite temperature. We also discuss the increase of the maximum operation temperature due to superconductivity and the peaklike features on the I–V curve of SISIS structures. © 1996 American Institute of Physics.
Show PACS
85.25.-j Superconducting devices
74.45.+c Proximity effects; Andreev reflection; SN and SNS junctions

Influence of the interfaces on the anisotropic magnetoresistance of Ni/Co multilayers

F. Lesmes, A. Salcedo, J. J. Freijo, D. Garcia, A. Hernando, and C. Prados

Appl. Phys. Lett. 69, 2596 (1996); http://dx.doi.org/10.1063/1.117711 (3 pages) | Cited 7 times

Full Text: | Download PDF

Show Abstract
Anisotropic magnetoresistance in Ni is found to increase abruptly when Co impurity layers are inserted. Some experiments carried out in different Ni/Co multilayers indicate that interfaces are responsible for the magnetoresistance enhancement. © 1996 American Institute of Physics.
Show PACS
75.70.Cn Magnetic properties of interfaces (multilayers, superlattices, heterostructures)
73.61.At Metal and metallic alloys
73.50.Jt Galvanomagnetic and other magnetotransport effects (including thermomagnetic effects)

Quantitative magnetic field measurements with the magnetic force microscope

Roger Proksch, George D. Skidmore, E. Dan Dahlberg, Sheryl Foss, J. J. Schmidt, Chris Merton, Brian Walsh, and Matt Dugas

Appl. Phys. Lett. 69, 2599 (1996); http://dx.doi.org/10.1063/1.117712 (3 pages) | Cited 23 times

Full Text: | Download PDF

Show Abstract
We have developed a technique to quantitatively image the magnetic field above a magnetic specimen using a modified magnetic force microscope (MFM). The technique depends on the nonlinear response of a magnetically soft MFM tip to the sample field and to an externally applied field, similar in principle to fluxgate magnetometry. We demonstrate the technique with high resolution, quantitative images of the magnetic field above a sample of longitudinal recording media. The magnetic field resolution is on the order of 1 Oe, with sub‐100 nm spatial resolution comparable to standard MFM techniques. © 1996 American Institute of Physics.
Show PACS
07.79.Pk Magnetic force microscopes
07.55.Ge Magnetometers for magnetic field measurements
Page 2 of 3 Pages Previous Page Next Page | Jump to Page
Close

Google Calendar

ADVERTISEMENT

Go to AIP Home   © AIP Publishing LLC
close