Tenaw, Tadesse2018-07-042023-11-092018-07-042023-11-092006-06http://10.90.10.223:4000/handle/123456789/6128Low dimensional nano crystals are known to have properties that can be markedly different from their bulk counterparts .For semiconductor crystals such as silicon when the carriers (excitons) are confined in dimensions less than their de Broglie wavelength (typically a few nanometers) quantum mechanical size effects emerge. In this dissertation the effects of these quantum confinements in silicon nanostructures are discussed in detail. Moreover, the different synthesis methods of silicon nanostructures and the accompanying characterizations of silicon nanocrystals and porous silicon are illustrated briefly. Theoretical analysis of the electronic structures of silicon nanocrystals of small number of atoms using pseudo potential-DFT method is presented. Finally the potential applications of these crystals in the electronic industry, nanobiotechnology and medicine are pointed out shortly. Precisely the purpose of this dissertation is, thus, to review: 􀂾 What nanostructures are? 􀂾 What nanotechnology is? 􀂾 How quantum confinement affects a nanostructure? 􀂾 How silicon and its properties behave at nano scale? 􀂾 What methods are used to synthesize silicon nanostructures? 􀂾 How computational approximation methods are applied on nanostructures? 􀂾 What future outlooks regarding nanoscience and nanotechnology prevail? 􀂾 What potential applications does Silicon nanostructures in particular and Nanotechnologies in general have?enNanostructuresThesis