Growth And Optical Properties Of Si/Ge Nanocrvstals Embedded In SiO₂ Matrix

Silicon and germanium nanomaterials have a wide application foreground in the field of microelectronics and optoelectronics for their superior properties and optoelectronic characteristics which are different from general materials. Among them, Si/Ge nanocomposite films, composed of Si/Ge nanoparticles, can generate some optoelectronic effects like optical bandgap broaden and photoluminescence for the quantum confinement effect, having tremendous application potential in silicon-based light emitters, infrared detectors, single electron device, photovoltaic materials and so on. The key to the research of the above mentioned applications is growing Si/Ge nano-films with high qualities.Si/Ge nanocrystals embedded in SiO₂ films were prepared by reactive magnetron sputtering. Technological conditions of Si/Ge nanocrystals growth was studied, as well as the relationship between preparation conditions and the density, size and distribution of the nanocrystals embedded in films. Spectrophotometer, X-ray photoelectron spectroscopy, scanning electron microscope, transmission electron microscope, raman spectrum, fluorescence spectrum and other testing methods were applied to characterize the thin film samples.Based on the study of Si nanocrystal films growth, the composition and optical constants of SiO_x films deposited at room temperature was found to be tuned by sputtering atmosphere, especially the oxygen flow rate. After high temperature rapid annealing process, a small amount of Si nanocrystals were obtained in SiO_x films. In addition, the affection of different annealing process conditions on SiO_x films was also researched.For Ge nanocrystal films, GeSiO hybrid films were deposited as the first step. After vacuum annealing process at 700?, Ge nanocrystals with high density and small size was successfully obtained. Also, the influence of different sputtering conditions and annealing temperature on Ge nanocrystal films was studied. On the basis of monolayer Ge nanocrystal films, multilayer NC-Ge/SiO₂ films was deposited to confine the size of Ge nanocrystals, where the role of SiO₂ separation layer was proved. Ge nanocrystals embedded in NC-Ge/SiO₂ films was distributed uniformly, whose fluorescence effect and optical bandgap were explored later.The research on the growth of Si/Ge nanocrystals embedded in SiO₂ films by reactive magnetron sputtering would lay a foundation of the following growth of Si/Ge nanocrystal films with high qualities and the study of the related devices.