DIAMOND HEXAGONAL SILICON PHASE AND (113) DEFECTS - ENERGY CALCULATIONS AND NEW DEFECT MODELS

The hypothesis that the precipitation of self-interstitial Si atoms leads to the formation of the diamond hexagonal Si phase, inside the structure of {113} stacking faults and rod-like defects, is reviewed on the basis of calculations of the total energy of the defects and high-resolution electron microscopy (HREM) image simulations. The relaxed atomic structures of several {113} defect models is obtained by the statics molecular method. The results of the calculations of the total energy of these models show that three new models present an energy lower than all other previously reported models of the {113} defects. The displacement vectors obtained from these models agree with available experimental data. These models also account for the experimentally observed transformation of the {113} defects into {111} faulted loops and perfect loops. From HREM image simulations it is shown that the major features of the experimental images are well reproduced in the simulated images. These findings allow us to define the aforementioned hypothesis as another possible mechanism of formation of the diamond hexagonal Si phase, leading to the presence of some layers of this phase into the structure of the rod-like and {113} defects.