The effect of hydrogen passivation on the photoluminescence of Si-rich superlattices is investigated. The as-grown samples show many defect-related luminescence signals and several additional luminescence peaks believed to originate from the superlattice. The background luminescence along with the dislocation and defect lines are found to be passivated by the hydrogen atoms. The intensity of the superlattice peak increases after passivation and its phonon replica, initially submerged in the background and defect luminescence signals, is highlighted. After a subsequent temperature annealing in N2, the background luminescence is increased as hydrogen outdiffuses but the superlattice main peak decreases, perhaps due to the change of the carrier lifetime.
Evidence of native gallium antisite defects in semiinsulating liquidencapsulated Czochralskigrown GaAsThe shallow defect evolution in Si-implanted and -annealed liquid-encapsulated Czochralskigrown GaAs is investigated by photoluminescence experiments. Three major emission lines are found. The first emission line located at 1.492 eV corresponds to the Si Ga -CAS radiative recombination. The remaining two lines located at 1.44 and 1.40 eV are shown to correspond to Gal-Si.",s and VAs-Si As radiative recombinations, respectively. The effects of these three shallow centers on the silicon activation efficiency are discussed with respect to different annealing and implantation conditions. 1246
Statement of the problemThe ease and extensive use of digital imaging systems raise serious questions about integrity and authenticity of digital images particularly in medical applications. A medical image requires great integrity of content since any change in the image might affect the diagnosis even if it is ofsmall amount. Fragile watermark could be the best technique to provide efficient image authentication tool for medical images, in this paper we present different methods developed in image watermarking used in order to verify integrity and authenticity of images We will present after that our proposed method and validated the embedding and extracting procedures
The visual interpretation of gestures provides the most natural and intuitive interaction. However its implementation remains very difficult. Consequently gesture recognition research tries to developing systems that are able to analyze, recognize and interpret the gestures captured by a camera. In this article we give an overview of a current research. Firstly by defining a specific number of terms then by presenting the current methods and examples of applications in gesture recognition.
Ultrathin Ge/Si strained-layer superlattices (SLS’s) with periodicities of a few monolayers have been successfully grown and characterized by Raman scattering spectroscopy. Structures with alternating Ge and Si layers were grown on Si substrates of different orientations. A thick 200 nm Ge0.4Si0.6 buffer layer was grown prior to the growth of the superlattice to make the strain distribution of the superlattice symmetrical and thus to maintain the pseudomorphic growth of the superlattices. Folded acoustic phonon peaks observed from these Ge/Si SLS samples can be used to determine the superlattice periodicity. The observed optical phonon frequencies were found to depend strongly on superlattice periodicity. A quantitative interpretation of this phenomenon was presented. Subsequent annealing of these samples reveals that the transition from pure Ge and/or Si layers to GexSi1−x alloy becomes more pronounced as the annealing time and temperature increase.
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