The modification of Si nanocrystallites embedded in a dielectric matrix by high energy ion irradiation
We have followed the effects of heavy ion irradiation on the structural, electrical, and photoluminescence properties of ensembles of silicon nanocrystallites embedded in a dielectric (SiO2) matrix. This was done as a function of the irradiation dose and the content of the Si phase. The results obtained can be accounted for self-consistently assuming that a relatively small dose of the irradiation enhances the crystallization while for higher doses the irradiation enhances the amorphization. The corresponding processes suggest that tuning of the above properties can be achieved by swift heavy ion irradiation.
Si Nanocrystal Arrays Created in SiO 2 Matrix by High-Energy Ion Bombardment
In the next two decades, nanoscience and nanotechnologies will transfer into new products and processes. One emerging area where this challenge will be successfully met is the field of semiconductor nanocrystals (NCs) (see, for instance, Norris et al., 2008). The promises offered by dielectric layers with hosted semiconductor nanocrystals in applications include production of silicon-based light emitting systems (Iacona et al., 2006), wavelength-tunable lasers (Klimov et al., 2007), memory elements (Hu et al., 2009), solar cells (Gur et al., 2008), low-dimensional devices (for instance, single electron transistors operating at room temperature (Zhou et al., 2010)), and a wide spectrum of biotechnologies (for instance, bioimaging (Michalet et al., 2005)). The prospects for developing new electronic and optoelectronic devices on the basis of spatially ordered arrays of quantum dots (QDs) embedded in a semiconductor or insulator matrix have arouse currently growing interest in the production methods of such arrays and in the studies of their optical and electronic properties.
Far-field dispersal modeling for fuel-air-explosive devices
A computer model for simulating the explosive dispersal of a fuel agent in the far-field regime is described and is applied to a wide variety of initial conditions to judge their effect upon the resulting fuel/air cloud. This work was directed toward modeling the dispersal process associated with Fuel-Air-Explosives devices. The far-field dispersal regime is taken to be that time after the initial burster charge detonation in which the shock forces no longer dominate the flow field and initial canister and fuel mass breakup has occurred. The model was applied to a low vapor pressure fuel, a high vapor pressure fuel and a solid fuel. A strong dependence of the final cloud characteristics upon the initial droplet size distribution was demonstrated. The predicted fuel-air clouds were highly non-uniform in concentration. 18 refs., 86 figs., 4 tabs.