Silicon carbide (SiC) has a number of remarkable physical and chemical properties that make it a promising new material in various fields of applications.
The high electron mobility and saturation drift velocity as well as the high band gap and breakdown field in conjunction with its unique thermal stability and conductivity unveil SiC as the ideal candidate for high-power, high-frequency and high-temperature electronic and optoelectronic devices exceeding conventional silicon based solutions \cite{wesch96,morkoc94,casady96,capano97,pensl93}.
-Due to the large Si--C bonding energy SiC is a hard and chemical inert material suitable for applications under extreme conditions and capable for microelectromechanical systemis, both as structural material and as a coating layer \cite{sarro00,park98}.
+Due to the large Si--C bonding energy SiC is a hard and chemical inert material suitable for applications under extreme conditions and capable for microelectromechanical systems, both as structural material and as a coating layer \cite{sarro00,park98}.
Its radiation hardness allows the operation as a first wall material in nuclear reactors \cite{giancarli98} and as electronic devices in space \cite{capano97}.
The realization of silicon carbide based applications demands for reasonable sized wafers of high crystalline quality.
-Despite the tremendous progress achieved in the fabrication of high purity SiC employing techniques like the modified Lely process for bulk crystal growth \cite{tairov78,tsvetkov98} or chemical vapour deposition (CVD) and molecular beam epitaxy (MBE) for homo- and heteroepitaxial growth \cite{kimoto93,powell90,fissel95}, available wafer dimensions and crystal qualities are not yet considered sufficient enough.
+Despite the tremendous progress achieved in the fabrication of high purity SiC employing techniques like the modified Lely process for bulk crystal growth \cite{tairov78,tsvetkov98} or chemical vapor deposition (CVD) and molecular beam epitaxy (MBE) for homo- and heteroepitaxial growth \cite{kimoto93,powell90,fissel95}, available wafer dimensions and crystal qualities are not yet considered sufficient enough.
Another promising alternative to fabricate SiC is ion beam synthesis (IBS).
High-dose carbon implantation at elevated temperatures into silicon with subsequent annealing results in the formation of buried epitaxial SiC layers \cite{borders71,reeson87}.
-A two-temperature implantation technique was proposed to achieve single crytalline SiC layers and a sharp SiC/Si interface \cite{lindner99,lindner99_2,lindner01,lindner02}.
+A two-temperature implantation technique was proposed to achieve single crystalline SiC layers and a sharp SiC/Si interface \cite{lindner99,lindner99_2,lindner01,lindner02}.
Although high-quality SiC can be achieved by means of IBS the precipitation mechanism is not yet fully understood.
-High resolution transmisson electron microscopy studies indicate the formation of C-Si interstitial complexes sharing conventional silicon lattice sites (C-Si dumbbells) during the implantation of carbon in silicon.
+High resolution transmission electron microscopy studies indicate the formation of C-Si interstitial complexes sharing conventional silicon lattice sites (C-Si dumbbells) during the implantation of carbon in silicon.
These C-Si dumbbells agglomerate and once a critical radius is reached, the topotactic transformation into a SiC precipitate occurs \cite{werner97,lindner01}.
In contrast, investigations of strained Si$_{1-y}$C$_y$/Si heterostructures form
ed by MBE~\cite{strane94,guedj98}, which incidentally involve the formation of SiC nanocrystallites, suggest an initial coherent precipitation by agglomeration of substitutional instead of interstitial C.
In chapter \ref{chapter:sic_rev} a review of the Si/C compound is given including the very central discussion on two controversial precipitation mechanisms present in literature in section \ref{section:assumed_prec}.
Chapter \ref{chapter:basics} introduces some basics and internals of the utilized atomistic simulations as well as special methods of application.
Details of the simulation and associated test calculations are presented in chapter \ref{chapter:simulation}.
-In chapter \ref{chapter:defects} results of investigations of single defect configurations, structures of comnbinations of two individual defects as well as some selected diffusion pathways in silicon are shown.
+In chapter \ref{chapter:defects} results of investigations of single defect configurations, structures of combinations of two individual defects as well as some selected diffusion pathways in silicon are shown.
These allow to draw conclusions with respect to the SiC precipitation mechanism in Si.
More complex systems aiming to model the transformation of C incorporated in bulk Si into a SiC nucleus are examined in chapter \ref{chapter:md}.
Finally a summary and some concluding remarks are given in chapter \ref{chapter:summary}.
projects / lectures / latex.git / blobdiff