| 11. |
- Buyanova, Irina, 1960-, et al.
(author)
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Mechanism for low-temperature photoluminescence in GaNAs/GaAs structures grown by molecular-beam epitaxy
- 1999
-
In: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 75:4, s. 501-
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Journal article (peer-reviewed)abstract
- The mechanism for low-temperature photoluminescence (PL) emissions in GaNAs epilayers and GaAs/GaNxAs1 - x quantum well (QW) structures grown by molecular-beam epitaxy is studied in detail, employing PL, PL excitation, and time-resolved PL spectroscopies. It is shown that even though quantum confinement causes a strong blueshift of the GaNAs PL emission, its major characteristic properties are identical in both QW structures and epilayers. Based on the analysis of the PL line shape, its dependence on the excitation power and measurement temperature, as well as transient data, the PL emission is concluded to be caused by a recombination of excitons trapped by potential fluctuations in GaNAs.
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| 12. |
- Buyanova, Irina, 1960-, et al.
(author)
-
Thermal stability and doping efficiency of intrinsic modulation doping in InP-based structures
- 1999
-
In: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 75:12, s. 1733-
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Journal article (peer-reviewed)abstract
- Doping efficiency and thermal stability of intrinsic modulation doping in InP/InGaAs heterostructures, where intrinsic defects (PInantisites) are used as an electron source, are investigated. A high efficiency of the intrinsic doping is demonstrated from a comparison between the intrinsically doped and conventional extrinsically doped structures. The thermal stability of the intrinsically doped heterostructures is shown to be largely affected by the thermal stability of the InP surface.
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| 13. |
- Chirita, Valeriu, et al.
(author)
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Enhanced cluster mobilities on Pt(111) during film growth from the vapor phase
- 1998
-
In: Applied Physics Letters. - : American Institute of Physics (AIP). - 0003-6951 .- 1077-3118. ; 72:1, s. 127-129
-
Journal article (peer-reviewed)abstract
- We use molecular dynamics simulations to follow the dynamics of small two-dimensional Pt clusters on Pt(111) at 1000 K. While close-packed Pt-7 heptamers are extremely stable structures, the addition of a single cluster vacancy or an on-top adatom immediately results in intracluster bond breaking, reconfigurations, rotations, the introduction of stacking faults, and greatly enhanced cluster diffusion rates. Mapping center-of-mass motion for total simulation times >145 ns revealed increases in cluster velocities by more than an order of magnitude with cluster migration occurring primarily by concerted motion and a novel diffusion mechanism involving double shearing of dimers/trimers. Contrary to some previous reports, edge-atom diffusion plays only a minor role. (C) 1998 American Institute of Physics.
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| 14. |
- Domeij, Martin, et al.
(author)
-
Stable dynamic avalanche in Si power diodes
- 1999
-
In: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 74:21, s. 3170-3172
-
Journal article (peer-reviewed)abstract
- A stable dynamic avalanche at a maximum power density of about 2.4 MW/cm(2) was measured in small areas of 3.3 kV Si power diodes, using an optical measurement technique, and very good dynamic ruggedness was verified in a conventional turn-off measurement. Device simulations of a diode with a shallow n(+) emitter indicate that impact ionization at the nn(+) junction can result in negative differential resistance (NDR) and current filamentation, whereas a deep n(+) emitter in the experimentally studied diode suppresses NDR. It is, therefore, proposed that the deep n(+) emitter is important for the stable dynamic avalanche.
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| 15. |
- Elsner, J., et al.
(author)
-
Effect of oxygen on the growth of (101‾0) GaN surfaces : The formation of nanopipes
- 1998
-
In: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 73:24, s. 3530-3532
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Journal article (peer-reviewed)abstract
- Local density-functional methods are used to examine the behavior of O and O-related defect complexes on the walls of nanopipes in GaN. We find that O has a tendency to segregate to the (10 1̄ 0) surface and identify the gallium vacancy surrounded by three oxygen impurities [VGa-(ON)3] to be a particularly stable and electrically inert complex. We suggest that during Stranski-Krastanow growth, when interisland spaces shrink, these defects reach a critical concentration beyond which further growth is prevented and nanopipes are formed
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| 16. |
- Georgsson, K, et al.
(author)
-
TRANSMISSION ELECTRON-MICROSCOPY INVESTIGATION OF THE MORPHOLOGY OF INP STRANSKI-KRASTANOW ISLANDS GROWN BY METALORGANIC CHEMICAL-VAPOR-DEPOSITION
- 1995
-
In: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 67:20, s. 2981-2982
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Journal article (peer-reviewed)abstract
- We have used transmission electron microscopy to determine the morphology of InP Stranski–Krastanow islands in GaInP, grown by metalorganic chemical vapor deposition at 580 °C. We investigated both capped and uncapped islands. It was found that the fully developed islands have the principal shape of truncated pyramids with a hexagonal base both before and after overgrowth. The planes defining the islands are of {001}, {110}, and {111} types. The base dimensions are 40–50 nm and 55–65 nm in the [1̄10] and [110] directions, respectively, and the height is 12–18 nm.
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| 17. |
- Gevorgian, Spartak, 1948, et al.
(author)
-
Effects of degraded edges in strips of high‐temperature superconducting films at microwave frequencies
- 1995
-
In: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 67, s. 1615-
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Journal article (peer-reviewed)abstract
- A simple model is proposed to analyzemicrowave properties of thin superconducting strips with degraded edge regions. A high resistance edge is assumed in the superconducting strip. It is shown that with increased temperature more current will flow inside the superconducting strip away from the damaged edge resulting in a reduction of effective surfaceresistance.
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| 18. |
- Hammar, M., et al.
(author)
-
Topography dependent doping distribution in selectively regrown InP studied by scanning capacitance microscopy
- 1998
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In: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 72:7, s. 815-817
-
Journal article (peer-reviewed)abstract
- We have used scanning capacitance microscopy (SCM) to study the dopant distribution in regrown InP with high sensitivity and spatial resolution. Sulfur or iron doped InP was selectively regrown around n-doped InP mesas using hydride vapor phase epitaxy, and the resulting structure was imaged in cross section by SCM. For calibration purposes, reference layers with known doping levels were grown directly on top of the region of interest. Dramatic variations in the carrier concentration around the mesa, as well as pronounced differences in the behavior of S and Fe are observed. We correlate these findings to the growth and doping incorporation mechanisms. © 1998 American Institute of Physics.
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| 19. |
- Kaplan, Alexander
(author)
-
Surface processing with non-Gaussian beams
- 1997
-
In: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 70:2, s. 264-266
-
Journal article (peer-reviewed)abstract
- The heat transfer problem of a moving source of heat scanning over a semi-infinite solid is of considerable importance for surface processing with high energy beams. The analytical solution of a moving Gaussian beam is extended by superposition of several Gaussian beams in order to approximate real beam shapes, thus providing high flexibility and accuracy. By superimposing two concentric beams, a real intensity profile with a central minimum was approximated with an accuracy of 13% compared to 35% for the conventional Gaussian beam approach. For the corresponding temperature field, an error of 57% for the depth and 17% for the width of the melt pool was eliminated
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| 20. |
- Kawamura, J., et al.
(author)
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Low noise NbN lattice-cooled superconducting hot-electron bolometric mixers at submillimeter wavelengths
- 1997
-
In: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 70:12, s. 1619-1621
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Journal article (peer-reviewed)abstract
- Lattice-cooled superconducting hot-electron bolometric mixers are used in a submillimeter-wave waveguide heterodyne receiver. The mixer elements are niobium nitride film with 3.5 nm thickness and ∼ 10 μm2 area. The local oscillator power for optimal performance is estimated to be 0.5 μW, and the instantaneous bandwidth is 2.2 GHz. At an intermediate frequency centered at 1.4 GHz with 200 MHz bandwidth, the double sideband receiver noise temperature is 410 K at 430 GHz. The receiver has been used to detect molecular line emission in a laboratory gas cell.
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