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T. Hakkarainen E.-M. Pavelescu J. Likonen 《Physica E: Low-dimensional Systems and Nanostructures》2006,32(1-2):266
GaInNAs/GaAs quantum wells grown by molecular beam epitaxy under different arsenic pressures have been studied using photoluminescence (PL), X-ray diffraction (XRD) and secondary-ion mass spectrometry (SIMS). The best optical properties are achieved with the V/III beam equivalent pressure ratio (V/IIIBEP) of 10. The PL emission wavelength remains unchanged for 8V/IIIBEP12, suggesting that within this range neither the alloy composition nor the nitrogen sticking coefficient is changed. For the lower and higher V/IIIBEP ratios the PL wavelength is red-shifted or blue-shifted, respectively. The XRD results indicate that the nitrogen incorporation into the group-V sub-lattice is enhanced at low As pressures and reduced at high As pressures. The PL behaviour can thus be understood as a competition between As and N adatoms in occupying anion lattice sites. 相似文献
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I. Vasiliu M. Gartner M. Anastasescu L. Todan L. Predoana M. Elisa C. Grigorescu C. Negrila C. Logofatu M. Enculescu A. Moldovan G. Pavelescu M. Zaharescu 《Optical and Quantum Electronics》2007,39(4-6):511-521
We intend to prepare periodic multilayered structures for photonic applications. With this goal we have performed a study
of some characteristics of SiO
x
-P2O5 films deposited by the sol–gel method on glass and ITO (InSnO
x
)-coated glass. The as prepared films were annealed to different temperatures (150 and 200°C). The chemical composition of
the samples was determined by X-ray Photoelectron Spectroscopy (XPS). The XPS results revealed the presence of P in the as-deposited
films. The structural an optical properties were examined by Fourier Transform Infrared Spectroscopy (FTIR), Spectroellipsometry
(SE) and UV Transmission Spectroscopy. IR spectra of the deposited films attest the interaction of an amorphous SiO2 with the H3PO4 used as a P-precursor. Refractive indices for individual SiO
x
-P2O5 determined from SE measurements show a densification of the layer structure with the increasing temperature in the thermal
treatment. The UV transmission spectra revealed a lower transmission for the sol-gel SiO
x
-P2O5 films as compared to ITO/glass substrate. AFM images proved the densification of the films with annealing in agreement with
the ellipsometric results.
The work was originally presented at “Physics of Photonic Crystals and Metamaterials (PPCM)” Workshop, Brussels, 12–15 June,
2006. 相似文献
3.
The experimental determination of the main plasma parameters (i.e. plasma potential, plasma density, electron temperature, intensity of plasma radiation) in the negative glow of a cylindrical cathode discharge in magnetic field is presented. The influence of electrode configuration, gas pressure, discharge current and magnetic field on plasma parameters and their radial distribution is analysed. 相似文献
4.
Pavelescu D. Nitu S. Dumitrescu G. Trucsa V. Zoita V. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1999,27(4):938-943
The paper presents one stage of the scientific research, performed for the investigation of the post-arc (p.a.) current within low voltage switching process in vacuum, when interrupting short-circuit currents of high values. A large power equipment, supplied by the mains and providing an accurate reproduction of the processes, concerning the short circuit phenomenon (U=1.5 kV; I=100 kA) was used. An experimental model, which can reproduce the switching conditions of the power circuit-breaker in vacuum, was available as well. The influence of an axial magnetic field on the p.a. current and the switching process was also explored 相似文献
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C.E.A. Grigorescu E. Valerio L. Tortet G. Pavelescu C. Ducu H.J. Trodahl N. Strickland W.R. Branford 《Applied Surface Science》2007,253(19):8102-8106
Thin films of nonstoichiometric Heusler alloys Co2MnSbxSn1−x (x = 0.2; 0.4; 0.6; 0.8) have been grown by pulsed laser deposition (double-target/double beam configuration) on Si (1 0 0) substrates using a KrF excimer laser (λ = 248 nm, τ = 20 ns). The substrate temperature was held at 300 K in all experiments to prevent interface interdiffusion of the species. A comparison between the compositions of films and corresponding targets has been done through energy dispersive X-ray spectroscopy (EDS) analysis showing a very satisfactory match. Scanning electron microscopy (SEM) imaging served to investigate the morphology of the films in order to determine the size and density of droplets which may influence the optical data. Optical conductivity derived from reflectivity measurements shows absorption onsets close to 1 eV, which corresponds to the onset of valence-to-conduction transitions in the minority spin bands theoretically predicted. The values of the saturation magnetisation measured at 300 K on the quaternary alloys are very close to those of ternary ones for which either half-metallic properties or high spin polarisation were theoretically predicted. 相似文献
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