X-Git-Url: https://hackdaworld.org/gitweb/?p=lectures%2Flatex.git;a=blobdiff_plain;f=posic%2Fthesis%2Fsummary_outlook.tex;h=dd01f148627f9544c62a16982fcae63112f829ae;hp=fe97f69d71d6a93645b74db0053d38c0132f5898;hb=a864a19fba9f7dca4340934edc60907462bff4e9;hpb=cf625066e6ada2a8d680e2a77bb2f5c6eb5122ab diff --git a/posic/thesis/summary_outlook.tex b/posic/thesis/summary_outlook.tex index fe97f69..dd01f14 100644 --- a/posic/thesis/summary_outlook.tex +++ b/posic/thesis/summary_outlook.tex @@ -1,6 +1,21 @@ \chapter{Summary and conclusions} \label{chapter:summary} +In a short review of the C/Si compound and the fabrication of the technologically promising semiconductor SiC by IBS, two controversial assumptions of the precipitation mechanism of 3C-SiC in c-Si are elaborated. +To solve this controversy and contribute to the understanding of SiC precipitation in c-Si, a series of atomistic simulations is carried out. +In the first part, intrinsic and C related point defects in c-Si as well as some selected diffusion processes of the C defect are investigated by means of first-principles quatum-mechanical calculations based on DFT and classical potential calculations employing a Tersoff-like analytical bond order potential. +Shortcomings of the computationally efficient though less accurate classical potential approach compared to the quantum-mechanical treatment are revealed. +The study proceeds investigating combinations of defect structures and related diffusion processes exclusively by the first-principles method. +The applicability of the utilized bond order potential for subsequent MD simulations is discussed. +Conclusions on the precipitation based on the DFT results are drawn. +In the second part, classical potential MD simulations are performed, which try to directly reproduce the precipitation. +Next to the shortcomings of the potential, quirks inherent to MD are discussed and a workaround is proposed. +Although direct formation of SiC fails to appear, the results suggest a mechanism of precipitation, which is consistent with previous quantum-mechanical conclusions as well as experimental findings. + +Obtained results + + + Experimental studies revealed increased implantation temperatures to be more efficient than postannealing methods for the formation of topotactically aligned precipitates \cite{kimura82,eichhorn02}. In particular, restructuring of strong C-C bonds is affected \cite{deguchi92}, which preferentially arise if additional kinetic energy provided by an increase of the implantation temperature is missing to accelerate or even enable atomic rearrangements.