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

18 May 1992

Volume 60, Issue 20, pp. 2451-2563

Page 2 of 2 Pages Previous Page | Jump to Page

Two‐dimensional lattice‐mismatched heteroepitaxy of germanium on silicon beyond the critical thickness by introducing a surfactant

H. J. Osten, J. Klatt, G. Lippert, E. Bugiel, and S. Hinrich

Appl. Phys. Lett. 60, 2522 (1992); http://dx.doi.org/10.1063/1.106926 (3 pages) | Cited 23 times

Full Text: | Download PDF

Show Abstract
Smooth germanium films have been grown on Si(100) surfaces in a two‐dimensional fashion by using antimony as a surfactant. Different ways of depositing the surfactant (at the interface between substrate and growing film, after the deposition of a thin Ge layer, and by coevaporation) have been investigated. The grown films, investigated by high‐resolution electron microscopy and reflection high‐energy electron diffraction, show that the surfactant does not act at the interface. A kinetical approach for the description of surfactant behavior in the growing front is necessary.
Show PACS
68.55.-a Thin film structure and morphology

Optical properties of free‐standing silicon quantum wires

G. D. Sanders and Yia‐Chung Chang

Appl. Phys. Lett. 60, 2525 (1992); http://dx.doi.org/10.1063/1.106927 (3 pages) | Cited 44 times

Full Text: | Download PDF

Show Abstract
We present theoretical studies of the optical properties of free‐standing Si quantum wires, using an empirical tight‐binding model which includes d orbitals and second‐neighbor interactions. The excitonic effects are included within the effective‐mass approximation. The predicted exciton transition energy for a quantum wire with a width of 27 Å agrees with the observed luminescence for a sample of similar size. We found that the thermally averaged exciton oscillator strengths for quantum wires with widths around 8 Å can become comparable to that of bulk GaAs.
Show PACS
78.66.-w Optical properties of specific thin films
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems

Increased modulation depth of submicron gratings produced by photoelectrochemical etching of GaAs

E. J. Twyford, P. A. Kohl, N. M. Jokerst, and N. F. Hartman

Appl. Phys. Lett. 60, 2528 (1992); http://dx.doi.org/10.1063/1.106928 (3 pages) | Cited 1 time

Full Text: | Download PDF

Show Abstract
Submicron optical diffraction gratings with improved modulation depth were photoelectrochemically etched on n‐GaAs. This etching technique uses an elevated etchant temperature to exceed the spatial resolution limits imposed by etching at room temperature, and provides a method of photoelectrochemical etching of gratings whose period is shorter than those of previously reported photoelectrochemically etched gratings. The improved grating modulation depth, the result of an increase in electrolyte temperature, was experimentally measured by etching 0.28 μm period gratings at five different temperatures. These results are compared with theoretical predictions based on analytical expressions for the reaction rate at the etched surface. Experimentally, a 25 °C increase in the etching temperature improved the grating amplitude by a factor of 1.7, which is in agreement with the theoretical predictions.
Show PACS
81.65.-b Surface treatments
73.40.Mr Semiconductor-electrolyte contacts
82.45.-h Electrochemistry and electrophoresis
42.79.Dj Gratings

CH4/H2: A universal reactive ion etch for II‐VI semiconductors?

M. A. Foad, C. D. W. Wilkinson, C. Dunscomb, and R. H. Williams

Appl. Phys. Lett. 60, 2531 (1992); http://dx.doi.org/10.1063/1.106929 (3 pages) | Cited 20 times

Full Text: | Download PDF

Show Abstract
A high resolution reactive ion etching process, capable of producing nanostructures less than 50 nm wide in a variety of II‐VI semiconductors, is described. Using a mixture of methane and hydrogen, binary II‐VI compound, e.g., ZnTe, ZnSe, CdTe, ZnS, CdS, and ternary compounds, e.g., CdMnTe and ZnSSe, have been etched. It would appear that the CH4/H2 gas mixture will play the same role for the II‐VI semiconductors as it does for the III‐Vs, that of seemingly ubiquitous etching system.
Show PACS
81.65.-b Surface treatments

Atomic resolution images of H‐terminated Si(111) surfaces in aqueous solutions

K. Itaya, R. Sugawara, Y. Morita, and H. Tokumoto

Appl. Phys. Lett. 60, 2534 (1992); http://dx.doi.org/10.1063/1.106904 (3 pages) | Cited 51 times

Full Text: | Download PDF

Show Abstract
The first atomic images of the hydrogen terminated Si(111) surface have been acquired in aqueous sulfuric acid solutions. The observed interatomic distance with threefold symmetry is ∼3.8 Å, indicating that the ideal Si(111):H‐1×1 surface can be prepared by chemical etching in NH4F solutions. It is demonstrated that in situ scanning tunneling microscopy is an extremely important method for revealing chemical processes with atomic resolution in the chemical etching of semiconductors in solutions.
Show PACS
81.65.-b Surface treatments
68.35.-p Solid surfaces and solid-solid interfaces: structure and energetics
07.79.Cz Scanning tunneling microscopes
61.05.-a Techniques for structure determination

Confined phonons in GaAs/AlAs superlattices with periodically corrugated interfaces

A. J. Shields, R. Nötzel, M. Cardona, L. Däweritz, and K. Ploog

Appl. Phys. Lett. 60, 2537 (1992); http://dx.doi.org/10.1063/1.106905 (3 pages) | Cited 21 times

Full Text: | Download PDF

Show Abstract
Using resonant Raman spectroscopy we have studied novel GaAs/AlAs superlattice (SL) structures, grown on (113) substrates, where the GaAs and AlAs layer widths vary periodically on a nanometer scale along the lateral [110] direction. We observe sharp confined LO phonon lines for both (113) and simultaneously grown (001) SLs, for a range of different layer widths, whose frequencies map the bulk GaAs LO dispersion. The confined phonon lines of the (113) SLs show a side peak, which can be assigned to a mode with finite k vector parallel to the layers, induced by the lateral periodicity.
Show PACS
63.20.D- Phonon states and bands, normal modes, and phonon dispersion
78.66.Fd III-V semiconductors
78.66.Hf II-VI semiconductors
78.30.Fs III-V and II-VI semiconductors
68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties

Luminescence quenching and the formation of the GaP1−xNx alloy in GaP with increasing nitrogen content

J. N. Baillargeon, K. Y. Cheng, G. E. Hofler, P. J. Pearah, and K. C. Hsieh

Appl. Phys. Lett. 60, 2540 (1992); http://dx.doi.org/10.1063/1.106906 (3 pages) | Cited 104 times

Full Text: | Download PDF

Show Abstract
A study of the luminescence properties of epitaxial GaP containing atomic N grown by molecular beam epitaxy using NH3 and PH3 as the column V sources was conducted. The 77 K photoluminescence spectra of the N‐doped epitaxial GaP showed a continuous redshift, from 5691 Å (2.18 eV) to 6600 Å (1.88 eV), resulted when the N concentration exceeded ∼5–7×1019 cm−3. This energy shift was found to be consistent with energy gap predictions using the dielectric theory of electronegativity for the GaP1−xNx system. The data also indicate that the emission intensity was maximum for N∼1×1020 cm−3, and then monotonically decreases with increasing N content. This is consistent with the formation of an indirect band‐gap semiconductor.
Show PACS
78.55.Cr III-V semiconductors
68.55.Nq Composition and phase identification
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
78.66.Fd III-V semiconductors
78.66.Hf II-VI semiconductors

Second‐harmonic generation and optical rectification using intersubband transitions in a biased p‐type semiconductor quantum well

Leung Tsang and Shun L. Chuang

Appl. Phys. Lett. 60, 2543 (1992); http://dx.doi.org/10.1063/1.106907 (3 pages) | Cited 25 times

Full Text: | Download PDF

Show Abstract
We present new theoretical results for the second‐harmonic and optical rectification coefficients due to intersubband transitions within the valence subbands of a p‐type quantum well in a biased external electric field. The results are based on the density matrix approach. Both the parabolic band model and the heavy‐hole/light‐hole valence band mixing model are utilized. With a moderate electric field of 10 and 150 kV/cm, it is shown that the second‐order susceptibilities are many times larger than those of bulk GaAs. The valence band mixing model also gives rise to a broader resonance phenomenon than the parabolic band model.
Show PACS
78.66.Fd III-V semiconductors
78.66.Hf II-VI semiconductors
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems
42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation
42.70.Nq Other nonlinear optical materials; photorefractive and semiconductor materials

Raman spectroscopic assessment of carbon‐hydrogen pairs in carbon‐doped GaAs layers

J. Wagner, M. Maier, Th. Lauterbach, K. H. Bachem, M. Ashwin, R. C. Newman, K. Woodhouse, R. Nicklin, and R. R. Bradley

Appl. Phys. Lett. 60, 2546 (1992); http://dx.doi.org/10.1063/1.106908 (3 pages) | Cited 17 times

Full Text: | Download PDF

Show Abstract
Raman scattering by local vibrational modes of carbon‐hydrogen pairs is reported for heavily carbon‐doped epitaxial GaAs layers. Scattering by the longitudinal carbon mode of these pairs at 452 cm−1 shows a strong resonant enhancement for incident photon energies approaching the E1 band‐gap energy of GaAs (≂3 eV). A possible mechanism for this resonance behavior is discussed in terms of the displacement of the carbon atom from its normal arsenic lattice site accompanied by a lengthening and weakening of the carbon‐gallium bonds when carbon‐hydrogen pairs form. The present findings demonstrate that resonant Raman scattering is an attractive tool for the detection of carbon‐hydrogen pair formation in thin carbon‐doped epitaxial GaAs layers grown from source materials containing hydrogen. The detection limit is estimated to be in the low 1018 cm−3 range.
Show PACS
78.30.Fs III-V and II-VI semiconductors
61.72.U- Doping and impurity implantation
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
63.20.Pw Localized modes

Electron accumulation in AlGaSb/InAs/AlGaSb quantum well system

S. Ideshita, A. Furukawa, Y. Mochizuki, and M. Mizuta

Appl. Phys. Lett. 60, 2549 (1992); http://dx.doi.org/10.1063/1.106909 (3 pages) | Cited 32 times

Full Text: | Download PDF

Show Abstract
The mechanism of the electron accumulation in the AlGaSb/InAs/AlGaSb QW system with Al composition higher than 0.5 is discussed. In this QW system, it is found that the dominant electron source is donor levels in AlGaSb rather than interface levels which have, so far, been proposed as the electron source. We have found two contradictory results, that undoped AlGaSb shows p‐type conduction and Be‐doping is compensated electrically, are satisfactorily explained by the model of coexistence of donors and a larger concentration of deep acceptors. Electron accumulation in InAs QW is shown to be controllable by shifting the quantum level with respect to the deep acceptor level.
Show PACS
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
73.50.Gr Charge carriers: generation, recombination, lifetime, trapping, mean free paths

Step edge YBa2Cu3O7−δ dc SQUIDs on sapphire substrates

C. W. Yuan, A. B. Berezin, and A. L. de Lozanne

Appl. Phys. Lett. 60, 2552 (1992); http://dx.doi.org/10.1063/1.106910 (3 pages) | Cited 10 times

Full Text: | Download PDF

Show Abstract
We have made YBa2Cu3O7−δ (YBCO) thin film dc superconducting quantum interference devices (SQUIDs) on sapphire substrates that operate above 77 K. The YBCO thin films are free of weak links and have critical current densities (Jc) of 106 A/cm2 at 77 K. Across the step edge, typical Jc ranges from 105 to 103 A/cm2 at 77 K and increases linearly with decreasing temperature. Typically, we obtain IcRn products near 30 μV at 77 K. We have operated the dc SQUIDs between 4.2 and 77 K and observed voltage modulation in rough agreement with the expected values. The flux noise is typically 1×10−10 Φ20/Hz, with a corresponding noise energy, SE, of 1.3×10−29 J/Hz at 77 K and 1 kHz.
Show PACS
85.25.Dq Superconducting quantum interference devices (SQUIDs)
74.50.+r Tunneling phenomena; Josephson effects
74.70.-b Superconducting materials other than cuprates

Extremely high frequency pulse magnetic resonance by picosecond magneto‐optic sampling

M. R. Freeman, M. J. Brady, and J. Smyth

Appl. Phys. Lett. 60, 2555 (1992); http://dx.doi.org/10.1063/1.106911 (3 pages) | Cited 19 times

Full Text: | Download PDF

Show Abstract
An exceptionally broadband method for pulse magnetic resonance detection is described which enables measurements over a broad range of applied magnetic fields and affords excellent coupling to microscopic specimens. Employing a picosecond magneto‐optic sampling technique with high temporal and spatial resolution, the precessing magnetization of a spin system is directly observed as a function of time following a photoconductively triggered spin tipping pulse. Free induction decays from 200 MHz to 200 GHz have been measured using a single device, for which the frequency limit in principle is of order 1 THz. Examples are presented for ferromagnetic resonance in yttrium iron garnet films at room temperature.
Show PACS
76.50.+g Ferromagnetic, antiferromagnetic, and ferrimagnetic resonances; spin-wave resonance
78.47.-p Spectroscopy of solid state dynamics
42.65.Re Ultrafast processes; optical pulse generation and pulse compression

Magnetically hard Sm2Fe17Nx prepared by nitriding melt‐spun ribbons

F. E. Pinkerton and C. D. Fuerst

Appl. Phys. Lett. 60, 2558 (1992); http://dx.doi.org/10.1063/1.106912 (3 pages) | Cited 30 times

Full Text: | Download PDF

Show Abstract
We have obtained magnetically hard Sm‐Fe‐N ribbons with a room‐temperature intrinsic coercivity Hci=23 kOe by nitriding melt‐spun Sm‐Fe precursor ribbons. Best results are obtained by grinding the ribbons to a <25 μm powder, then heat treating the powder in vacuum for 1 h at 700 °C prior to nitriding in N2 gas at 450–480 °C. X‐ray diffraction shows that the primary phase is rhombohedral Sm2Fe17Nx, or possibly the disordered hexagonal modification of this phase having the TbCu7 structure. Higher coercivities will be obtainable if the volume fraction of soft magnetic impurity phases, such as α‐Fe, can be reduced by optimizing the composition and processing.
Show PACS
81.20.Ev Powder processing: powder metallurgy, compaction, sintering, mechanical alloying, and granulation
75.50.-y Studies of specific magnetic materials
81.30.-t Phase diagrams and microstructures developed by solidification and solid-solid phase transformations

Low temperature synthesis of boron nitride from condensed diborane and ammonia using synchrotron radiation

D. R. Strongin, J. K. Mowlem, M. W. Ruckman, and Myron Strongin

Appl. Phys. Lett. 60, 2561 (1992); http://dx.doi.org/10.1063/1.106913 (3 pages) | Cited 15 times

Full Text: | Download PDF

Show Abstract
Synchrotron radiation was used to form boron nitride from a mixture of diborane (B2H6) and ammonia condensed on a silver substrate at 78 K. Photoemission and near‐edge x‐ray absorption fine structure results show valence band and near‐edge features characteristic of the hexagonal phase of boron nitride.
Show PACS
81.15.-z Methods of deposition of films and coatings; film growth and epitaxy
82.50.-m Photochemistry
Page 2 of 2 Pages Previous Page | Jump to Page
Close

Google Calendar

ADVERTISEMENT

Go to AIP Home   © AIP Publishing LLC
close