Especially substrates of the 3C polytype promise good quality, single crystalline GaN films~\cite{takeuchi91,yamamoto04,ito04}.
The focus of SiC based applications, however, is in the area of solid state electronics experiencing revolutionary performance improvements enabled by its capabilities.
-These devices include ultraviolet (UV) detectors, radio frequency (RF) amplifiers, rectifiers, switching transistors and MEMS applications.
+These devices include ultraviolet (UV) detectors, high power radio frequency (RF) amplifiers, rectifiers and switching transistors as well as MEMS applications.
For UV dtectors the wide band gap is useful for realizing low photodiode dark currents as well as sensors that are blind to undesired near-infrared wavelenghts produced by heat and solar radiation.
-These photodiodes serve as excellent sensors applicable for monitoring and control of turbine engine combustion.
-The low dark currents enable the use for X-ray, heavy ion and neutron detection in nuclear reactor monitoring and enhanced scientific studies of high-energy particle collisions as well as cosmic radiation.
+These photodiodes serve as excellent sensors applicable in the monitoring and control of turbine engine combustion.
+The low dark currents enable the use in X-ray, heavy ion and neutron detection in nuclear reactor monitoring and enhanced scientific studies of high-energy particle collisions as well as cosmic radiation.
+The low neutron capture cross section and radiation hardness favors its use in detector applications.
The high breakdown field and carrier saturation velocity coupled with the high thermal conductivity allow SiC RF transistors to handle much higher power densities and frequencies in stable operation at high temperatures.
Smaller transistor sizes and less cooling requirements lead to a reduced overall size and cost of these systems.
+For instance, SiC based solid state transmitters hold great promise for High Definition Television (HDTV) broadcast stations abandoning the reliance on tube-based technology for high-power transmitters significantly reducing the size of such transmitters and long-term maintenance costs.
+The high breakdown field of SiC compared to Si allows the blocking voltage region of a device to be designed roughly 10 times thinner and 10 times heavier doped, resulting in a decrease of the blocking region resistance by a factor of 100 and a much faster switching behavior.
+Thus, rectifier diodes and switching transistors with higher switching frequencies and much greater efficiencies can be realized and exploited in highly efficient power converters.
+Therefor, SiC constitutes a promising candidate to become the key technology towards an extensive development and use of regenerative energies and elctromobility.
+Beside the mentioned electrical capabilities the mechanical stability, which is almost as hard as diamond, and chemical inertness almost suggest SiC to be used in MEMS designs.
+
+Among the different polytypes of SiC, the cubic phase shows a high electron mobility and the highest break down field as well as saturation drift velocity.
+In contrast to its hexagonal counterparts 3C-SiC exhibits isotropic mechanical and electronic properties.
+Additionally the smaller band gap is expected to be favorable concerning the interface state density in MOSFET devices fabricated on 3C-SiC.
+Thus the cubic phase is most effective for highly efficient high-performance electronic devices.
+\begin{figure}[ht]
+\begin{center}
+\includegraphics[width=7cm]{sic_unit_cell.eps}
+\end{center}
+\caption{3C-SiC unit cell. Yellow and grey spheres correpsond to Si and C atoms respectively. Covalent bonds are illustrated by blue lines.}
+\label{fig:sic:unit_cell}
+\end{figure}
+Its unit cell is shown in Fig.~\ref{fig:sic:unit_cell}.
+3C-SiC grows in zincblende structure, i.e. it is composed of two fcc lattices, which are displaced by one quarter of the volume diagonal as in Si.
+However, in 3C-SiC, one of the fcc lattices is occupied by Si atoms while the other one is occupied by C atoms.
+Its lattice constant of \unit[0.436]{nm} compared to \unit[0.543]{nm} from that of Si results in a lattice mismatch of almost \unit[20]{\%}, i.e. four lattice constants of Si approximately match five SiC lattice constants.
+Thus, the Si density of SiC is only slightly lower, i.e. \unit[97]{\%} of plain Si.
+\section{Fabrication of silicon carbide}
-Focus on ... key ... to high efficiency
-name applications related to properties: diodes, rectifiers, inverters, HDTV alternative microwave tubes, sensors
+Although the constituents of SiC are abundant and the compound is chemically and thermally stable, large deposits of SiC have never been found.
+Due to the rarity, SiC is typically man-made.
+The development of several methods was necessary to synthetically produce SiC crystals matching the needs of a respective application.
+The fact that natural SiC is almost only observed as individual presolar SiC stardust grains near craters of primitive meteorite impacts, already indicates the complexity involved in the synthesis process.
-high saturation drift velocity high-frequency ...
-Mechanical stability almost like diamond ...
-Chemical inert, low neutron capture foobar ... radiation hardness
+The attractive properties and wide range of applications, however, have triggered extensive efforts to grow this material as a bulk crystal and as an epitaxial surface thin film.
+In the following, the principal difficulties involved in the formation of crystalline SiC and the most recent achievements will be summarized.
-isotropic properties ...
+Though possible, melt growth processes \cite{nelson69} are complicated due to the small C solubility in Si at temperatures below \unit[2000]{$^{\circ}$C} and its small change with temperature \cite{scace59}.
+High process temperatures are necessary and the evaporation of Si must be suppressed by a high-pressure inert atmosphere.
+Crystals grown by this method are not adequate for practical applications with respect to their size as well as quality and purity.
+The presented methods, thus, focus on vapor transport growth processes such as chemical vapor deposition (CVD) or molecular beam epitaxy (MBE) and the sublimation technique.
-Since in this work 3C-SiC unit cell ... two fcc lattices ...
+\subsection{SiC bulk crystal growth}
+The industrial Acheson process \cite{acheson} is utilized to produce SiC on a large scale by thermal reaction of silicon dioxide (silica sand) and carbon.
+Due to the insufficient and uncontrollable purity, material produced by this method, originally termed carborundum by Acheson, can hardly be used for device applications.
+However, it is often used as an abrasive material and as seed crystals for subsequent vapor phase growth and sublimation processes.
-\section{Fabrication of silicon carbide}
+van Arkel (CVD)
+
+Lely (sublimation)
+
+modified Lely or modified sublimation
+
+though significant advances have been achieved a bunch of defects ...
-SiC usually manmade.
-The unique properties driving its applications in the same time harden the fabrication of SiC ...
+\subsection{SiC epitaxial thin film growth}
\section{Ion beam synthesis of cubic silicon carbide}
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