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Ge/Si Core/Shell Quantum Dots in an Alumina Matrix: Influence of the Annealing Temperature on the Optical Properties
摘要： Structures with Ge/Si nanoparticles (quantum dots) in an aluminum-oxide matrix are of interest due to the combination of two basic semiconductors and the use of a matrix with a high permittivity and strong oxygen–metal bonding. In this study, multilayer nanoperiodic structures in the form of a substrate/Al2O3/Ge/Si/Al2O3…Al2O3 sequence of layers (with the period Al2O3/Ge/Si and the number of periods up to 20) are produced and then annealed at different temperatures. It is shown that, after annealing, the structures contain both Ge and Si crystalline particles, whose dimensions and number are defined by the deposited-layer thicknesses and the annealing temperature. The results obtained by different optical techniques suggest that the structures exhibit the quantum-confinement effect. This inference is supported by high-resolution microscopy.
关键词： Ge/Si,multilayer nanostructures,core–shell quantum dots
更新于2025-09-23 15:19:57
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Reversible Polarization Recording in As2S3–Se Multilayer Nanostructures
摘要： Polarization holographic recording of diffraction gratings and their subsequent erasure have been investigated on As2S3–Se multilayer nanostructures. The work investigates how preexposure to actinic laser radiation up to complete photoinduced changes in the optical properties affects the formation of diffraction gratings in the studied structure. It is shown that the preexposure of an As2S3–Se multilayer nanostructure (MNS) leads to photobleaching, and the maximum achievable diffraction efficiency (DE) of 35% does not change; however, the required exposure value is increased. It is also shown that exposure using one laser beam results in complete erasure of the diffraction grating recorded up to the maximum. Seven recording–erasure cycles show that the kinetics of the increase in diffraction efficiency and its maximum value do not change, which indicates that the As2S3–Se multilayer structure is capable of reversible holographic recording under orthogonal circular polarization. Study of the gratings recorded with an atomic-force microscope shows that the main factor determining the diffraction efficiency value is modulation of the relief, the depth of which is greater than 200 nm.
关键词： reversible holographic recording,chalcogenide multilayer nanostructures,diffraction efficiency,direct surface relief formation
更新于2025-09-10 09:29:36