Assefa, Gezahegn2018-06-262023-11-092018-06-262023-11-092007-03http://10.90.10.223:4000/handle/123456789/3509The optical properties of bulk Silicon are deeply modi ed if the material is manipulated at the nano metric size. In particular the growth of nanocrystalline Silicon(nc-Si) structures constitutes today a promissing approach for the develop- ment of Silicon based light emitting devices. In this thesis the in uence of quantum con nement on the optical properties of nc-Si is investigated.We basically concen- trate on the Photoluminescence (PL) of nc-Si. One of the fundamental parameters describing The PL mechanism of nc-Si is the radiative recombination rate. In order to examine the mechanism of the PL from the nc-Si the optical transition and the radiative transition rate are studied based on the quantum con nement(QC)model. We nd that the radiative recombination rate varies as . Where d3􀀀 is the diame- ter of the spherical crystallites. This result shows that the radiative recombination rate increases with decreasing the size of the nc-Si. As a result, the PL emission intensity enhanced due to QCE and the PL can be tuned into the visible rangeenPhotoluminescence MechanismThesis