Mosaic Of Sio <sub> 2 </ Sub> Dielectric In Si Nanocrystals, Preparation And Optical Characteristics Of El

Room temperature visible light emission from porous silicon (PS) and nanocrystal silicon (nc-Si) has opened a new era for optoelectronic integration based on Si. However for PS, the reactivity and fragile due to its porosity and possible pollution from its fabrication process prevent its practical applications in optoelectronical devices. While nc-Si embedded in SiO₂ matrix (nc-Si/SiO₂) is a promising material for Si optical application due to its robust structure, strong and stable photoluminescence, and its fabrication compatibility with microelectronic integrated technology.nc-Si/SiO₂ can be made by many different approaches and the most widely used one is based on phase separation and recrystalization. Sub-stoichiometric silica films (SiO_x) were deposited by different methods and annealed at 1100℃ in nitrogen ambient to form nc-Si/SiO₂. In this thesis, SiO_x film was deposited by vacuum evaporation of SiO powder. The SiO_x film was characterized by X-ray photoelectron spectroscopy (XPS) and after annealed at 1100℃, the presence of nc-Si was analyzed by Raman spectra and X-ray diffraction spectra.The first aim of our research is to determine whether the photoluminescence is from nc-Si. SiO_x films were annealed at different temperatures. It is found out that for annealing temperature(Ta) lower than 900℃ the PL spectra center at 620nm, and this PL becomes very weak when annealed at 1100℃ for 30min but another PL peaking around 710nm appears. Structure relaxation of the SiO_x film annealed at different temperatures was analyzed from micro-dynamics process to explain the PL origin. Combined with Raman spectra, 620nm PL is mainly related to oxygen defects and PL from Si clusters can't be ruled out however. On the other hand, 710nm PL is from nc-Si. Much attention was paid to the weak PL from sample annealed at 900℃.The important property of nc-Si is quantum size effect, which is referred to as...