研究目的
To produce Ge/Si core/shell quantum dots in an Al2O3 matrix and study the optical properties of the structures at different ratios between the components and at different annealing temperatures.
研究成果
The study successfully produced arrays of Ge–Si quantum dots in an aluminum-oxide matrix with different ratios between the amounts of Ge and Si. It was 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, supported by high-resolution microscopy.
研究不足
The study is limited by the technical constraints of the electron-beam evaporation and annealing processes, as well as the potential for optimization in the thicknesses of the deposited layers and annealing temperatures to achieve desired optical properties.
1：Experimental Design and Method Selection:
The study involved the production of multilayer nanoperiodic structures (MNSs) by alternate electron-beam evaporation onto an insulating or semiconductor substrate, followed by annealing in a nitrogen atmosphere to form semiconductor nanoinclusions in an insulating matrix.
2：Sample Selection and Data Sources:
The samples were fabricated with different thicknesses of Ge and Si nanolayers and annealed at temperatures of 700, 800, 850, and 900°C for 1 h.
3：List of Experimental Equipment and Materials:
Equipment included a JEM2100F transmission electron microscope (TEM), a spectrophotometric system based on an MDR-23 monochromator, and a Nabertherm RS 120/500/13 tube furnace for annealing.
4：Experimental Procedures and Operational Workflow:
The structures were produced by electron-beam vacuum evaporation of crystalline silicon, germanium, and polycrystalline corundum from separate crucibles. The layer thicknesses were monitored with a quartz sensor.
5：Data Analysis Methods:
The microstructure was studied using TEM, optical transmittance and specular reflectance spectra were recorded, and the absorption coefficient and band gap were calculated from the experimentally measured optical density.
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