排序方式: 共有32条查询结果,搜索用时 31 毫秒
21.
Mössbauer measurements were performed on GaAs implanted with129mTe-isotopes. A defect configuration is observed which is characterized by a large electric field gradient. This defect configuration shows persistent photoionisation and it is associated with the so-called “DX-center”. The time constant of the relaxation from the substitutional donor-site to the DX-center defect site is measured. 相似文献
22.
J.A. Peters Hong Chen Yue Pan Yafei Guan J.J. Heremans N. Goel S.J. Chung M.B. Santos W. Van Roy G. Borghs 《Physica E: Low-dimensional Systems and Nanostructures》2006,34(1-2):363
We report on the observation of localization, antilocalization and Altshuler–Aronov–Spivak (AAS) oscillations in antidot lattices patterned on high-mobility InSb/InAlSb and InAs/AlGaSb heterostructures. In addition, the antidot lattices display ballistic commensurability features. The strength of the localization peak in InSb antidot lattices decreases exponentially with temperature, with a high characteristic temperature of 25 K between 0.4 and 50 K. Analysis of the AAS oscillations enables the extraction of phase and spin coherence lengths in InAs. 相似文献
23.
Van Bael MJ Bekaert J Temst K Van Look L Moshchalkov VV Bruynseraede Y Howells GD Grigorenko AN Bending SJ Borghs G 《Physical review letters》2001,86(1):155-158
A scanning Hall probe microscope is used to study flux pinning in a thin superconducting Pb film covering a square array of single-domain Co dots with in-plane magnetization. We show that single flux quanta of opposite sign thread the superconducting film below T(c) at the opposite poles of these dipoles. Depending on the polarity of the applied field, flux lines are attracted to a specific pole of the dipoles, due to the direct interaction with the vortexlike structures induced by the local stray field. 相似文献
24.
This contribution deals with some selected aspects of Fast Ion Beam Collinear Laser Spectroscopy: (1) the study of h.f.i.
in free ions; (2) sensitive state selective particle detection; (3) laser-RF double resonance; and (4) laser frequency Doppler
tuning in external magnetic fields. 相似文献
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26.
R.R. Lieten O. Richard S. Degroote M. Leys H. Bender G. Borghs 《Journal of Crystal Growth》2011,314(1):71-75
Early efforts to grow GaN layers on germanium substrates by plasma assisted molecular beam epitaxy led to GaN domains, rotated by 8° relative to each other. Increased insight in the growth of GaN on germanium resulted in the suppression of these domain and consequently high quality layers. In this study the interface of these improved layers is investigated with transmission electron microscopy. The GaN layers show high crystal quality and an atomically abrupt interface with the Ge substrate. A thin, single crystalline Ge3N4 layer is observed in between the GaN layer and Ge substrate. This Ge3N4 layer remains present even at growth temperatures (850 °C) far above the decomposition temperature of Ge3N4 in vacuum (600 °C). Triangular voids in the Ge substrate are observed after growth. Reducing the Ga flux at the onset of GaN growth helps to reduce the triangular defect size. This indicates that the formation of voids in the Ge substrate strongly depends on the presence of Ga atoms at the onset of growth. However complete elimination was not achieved. The formation of voids in the germanium substrate leads to diffusion of Ge into the GaN layer. Therefore we examined the diffusion of Ge atoms into the GaN layer and Ga atoms into the Ge substrate. It was found that the diffusion of Ge into the GaN layer and Ga into the Ge substrate can be influenced by the growth temperature but cannot be completely suppressed. Our results suggest that Ga atoms diffuse through small imperfections in the Ge3N4 interlayer and locally etch the Ge substrate, leading to the diffusion of Ga and Ge atoms. 相似文献
27.
G. Borghs P. De Bisschop R. E. Silverans M. Van Hove J. M. Van den Cruyce 《Zeitschrift für Physik A Hadrons and Nuclei》1981,299(1):11-13
Collinear fast beam-laser spectroscopy has been performed on metastable 5d 4 D 7/2 Xenon ions. Hyperfine structure constants for the 6p 4 P 5/2 0 level have been derived for129Xe:A=?1,634.9±0.9 MHz and131Xe:A=485.3±0.3 MHz andB=?116.5±2.0MHz. Changes in mean squared nuclear charge radii are derived from the measured isotope shifts. 相似文献
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29.
InAs/(GaIn)Sb superlattices for IR optoelectronics: Strain optimization by controlled interface formation 总被引:1,自引:0,他引:1
J. Wagner J. Schmitz N. Herres F. Fuchs D. Serries B. Grietens S. Nmeth C. Van Hoof G. Borghs 《Physica E: Low-dimensional Systems and Nanostructures》1998,2(1-4)
The structural properties of InAs/(GaIn)Sb and (InGa)As/GaSb superlattices (SLs), grown by solid-source molecular-beam epitaxy on
GaAs substrates using a strain relaxed GaSb or InAs buffer layer or directly on
InAs substrates, were analyzed by high-resolution X-ray diffraction and Raman spectroscopy. The residual strain within the SL was found to depend critically on the type of interface bonds, which can be either InSb- or GaAs-like. Thus, to achieve lattice matching to the buffer layer or substrate by strain compensation within the SL stack, the controlled formation of the interface bonds is vital. On the other hand, minimization of the residual strain is shown to be a prerequisite for achieving a high photoluminescence yield and high responsivities for InAs/(GaIn)Sb SL based IR detectors. 相似文献
30.
129mTe-atoms were implanted in Al x Ga1?x As-samples (withx varying from 0 to 1) with a dose of 2×1013 atoms/cm2. After rapid thermal annealing to 900°C, a variation in the Mössbauer spectra as a function ofx is observed. Forx between 0.2 and 0.7, a component with a large electric field gradient is dominant in the spectra, while for the other values ofx a single line dominates. The presence of the component with a large electric field gradient coincides with the presence of the so-called “DX-center”. 相似文献