| Since the observation of strong photoluminescence (PL) of porous silicon, a great interest in nanocrystalline silicon (nc-Si) has been stimulated because of its potential applications as light-emitting devices compatible with silicon-based optoelectronic integrated circuits. Scientists have spent many years changing the light-emitting characteristics of Si-based materials and improving the light-emitting efficiency to several orders larger than that of Si. To date, studies of light emitting from the nanometer structure have widely been researched. Many ways of doping have also been reported. At the same time, to reduce the onset voltage and to increase the intensity of electroluminescence (EL) is all very important for EL devices. In this paper, we reported the structural and luminescent properties of Si-based oxide films containing semiconductor Si, Ge or metal Al powders prepared by a dual-ion-beam co-sputtering method (Si-SiO2 films and Al-Si-SiO2 films) or RF magnetron sputtering technique (Ge-SiO2 films), and analyze the PL and EL mechanism.1. The composite films of Si- SiO2 films were prepared by dual ion beam co-sputtering method from a composite target in argon atmosphere. The influence of depositing condition on the depositing rate and the structure of the films were studied by the aid of TEM and XRD. When the temperature (Ts<450℃ , Ta<800℃ ) is low, the structure of the samples is still amorphous. The majority content of the sample is SiO 90 by the aid of XPS. Ge-SiO2thin films were prepared by an RF co-sputtering technique on p-Si substrates from a Ge-SiO2 composite target. The as-deposited films were annealed in the temperature range of 300-1000 ℃ under nitrogen ambience. Thestructure of films was evaluated by x-ray diffraction (XRD), x-ray photoernission spectroscopy (XPS). The average size of nc-Ge, at Ta of 600,800,1000℃, evaluated according to Scherrer formula is about 3.9,4.7 and 6.1nm, respectively. From the results of XPS, for the sample annealed at lower Ta, the most content of the Ge related components is GeO2, and few content of Ge, GeO and Ge2O3. With the increases of Ta, the content of Ge increase, while the content of GeCh and Ge2O3 decrease, the content of GeO and SiO have the same properties of increase with Ta (maximum at Ta is 800℃), and then decreases dramatically. For Al-Si-SiO2 films, the structure is amorphous and the majority components of the sample are Al and SiO2.2. Quantum confinement effect was observed in the films by measurements of absorption spectrum of Ge-SiO2 films. The widening of optical band gap of the amorphous films seems to be related to the function of the quantum confinement on the impurities or defects in the films.3. The PL results of Si-SiO2 films show that emission spectra of samples have 4 luminescent band peak at 320nm, 410nm, 560nm, and630nm, respectively, at room temperature, Ta, the excitation wavelength, Argon pressure et al. , which means that there exist different kinds of structure in the films, are different in number of peaks, peak position as well as the intensity of peaks. The mechanisms of PL are discussed in detail. The PL characteristics of Ge-SiO2 films are closely dependent on the contents of Ge and its oxides in SiO2 matrix. The dependence observed strongly suggests that the PL peak at 394nm is related to the existence of GeO and 580nm to that of Ge nanocrystal (nc-Ge) in the films. It is found that the PL spectra of Al-Si-SiO2 films are composed of 3 bands located at about 370nm, 410nm, and 510nm, respectively. The peak position changes little with the different amount of Al, while the intensity of the PL peak changes. With the increase of the amount of Al, the intensity of the PL peak at 510nm increases. With the aid of PLE we can suggest that PL peak at 370nm and 410nm are related to the oxygen vacancies, and 510nm peak originate from a complex co-function of AL, Si, and O.EL devices have been fabricated on three types of silicon based oxide films(Ge-SiO2 films, Si-SiO2 films, and Al-SiO2 films)...
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