Study Of Nanocrystalline Ge Preparation And Neutron Transmutation Doping

Ge nanocrystals (nc-Ge) embedded into SiO₂ matrix are becoming a field of increasing interest due to visible and near-infrared photoluminescence (PL) and potential applications in novel optical data storage devices. Now the photoluminescence, electroluminescence and cathodeluminescence of nc-Ge have all been found. But the neutron-induct luminescence was not reported before. In bulk materials, doping is a useful tool to reveal the nature of PL. The role of impurities in nc-Ge is, of course, much weaker than that in bulk crystals because the surface states are dominating factor for nc. Nevertheless, in different systems, the influence of doping on the properties of nc-Ge should be studied experimentally. In this work, the samples were prepared by ion implantation, the PL characteristics of samples before and after NTD were studied.In this wok, the phenomenon of nc-Ge embedded in SiO₂ amorphous film, formed by high-dose-ion-implantation without subsequent annealing was found for the first time in the world. The physical mechanism of Ge nanocrystals embedded in SiO₂ amorphous film, formed by high-dose-ion-implantation without subsequent annealing, was studied by means of XRD, LRS, TEM, SEM analysis, and calculation of TRIM program. The nc-Ge existence was characterized and the threshold dose of nc-Ge formation was studied by GIXRD. By means of SEM and TEM analysis, these phenomena were found. The nanoparticles have a narrow size-distribution. The average size and uniformity of Ge nanoparticles change with ion fluences. The nanoparticles were composed of nano-crystalline Ge (nc-Ge) and nano-amorphous Ge (na-Ge) particles, the ratio of number of nc-Ge to na-Ge increases with the increase of ion fluence. The formation of these phenomena can be explained by a self-organization mechanism.