notes = "first time ibs at moderate temperatures",
}
+@Article{lindner96,
+ title = "Formation of buried epitaxial silicon carbide layers
+ in silicon by ion beam synthesis",
+ journal = "Materials Chemistry and Physics",
+ volume = "46",
+ number = "2-3",
+ pages = "147--155",
+ year = "1996",
+ note = "",
+ ISSN = "0254-0584",
+ doi = "DOI: 10.1016/S0254-0584(97)80008-9",
+ URL = "http://www.sciencedirect.com/science/article/B6TX4-3VSGY9S-8/2/f001f23c0b3bc0fc3fc683616588fbc7",
+ author = "J. K. N. Lindner and K. Volz and U. Preckwinkel and B.
+ Götz and A. Frohnwieser and B. Rauschenbach and B.
+ Stritzker",
+ notes = "dose window",
+}
+
+@Article{calcagno96,
+ title = "Carbon clustering in Si[sub 1-x]{C}[sub x] formed by
+ ion implantation",
+ journal = "Nuclear Instruments and Methods in Physics Research
+ Section B: Beam Interactions with Materials and Atoms",
+ volume = "120",
+ number = "1-4",
+ pages = "121--124",
+ year = "1996",
+ note = "Proceedings of the E-MRS '96 Spring Meeting Symp. I on
+ New Trends in Ion Beam Processing of Materials",
+ ISSN = "0168-583X",
+ doi = "DOI: 10.1016/S0168-583X(96)00492-2",
+ URL = "http://www.sciencedirect.com/science/article/B6TJN-3VSHB0W-1S/2/164b9f4f972a02f44b341b0de28bba1d",
+ author = "L. Calcagno and G. Compagnini and G. Foti and M. G.
+ Grimaldi and P. Musumeci",
+ notes = "dose window, graphitic bonds",
+}
+
+@Article{lindner98,
+ title = "Mechanisms of Si{C} Formation in the Ion Beam
+ Synthesis of 3{C}-Si{C} Layers in Silicon",
+ journal = "Materials Science Forum",
+ volume = "264-268",
+ pages = "215--218",
+ year = "1998",
+ note = "",
+ doi = "10.4028/www.scientific.net/MSF.264-268.215",
+ URL = "http://www.scientific.net/MSF.264-268.215",
+ author = "J. K. N. Lindner and W. Reiber and B. Stritzker",
+ notes = "intermediate temperature for sharp interface + good
+ crystallinity",
+}
+
@Article{lindner99,
title = "Controlling the density distribution of Si{C}
nanocrystals for the ion beam synthesis of buried Si{C}
Even better qualities by direct synthesis were obtained for implantations at \unit[950]{$^{\circ}$C} \cite{nejim95}.
Since no amorphous or polycrystalline regions have been identified, twinning is considered to constitute the main limiting factor in the \ac{IBS} of SiC.
-Further studies revealed the possibility to form buried layers of SiC by IBS at moderate substrate and anneal temperatures \cite{lindner95}.
+Further studies revealed the possibility to form buried layers of SiC by IBS at moderate substrate and anneal temperatures \cite{lindner95,lindner96}.
Different doses of C ions with an energy of \unit[180]{keV} were implanted at \unit[330-440]{$^{\circ}$C} and annealed at \unit[1200]{$^{\circ}$C} or \unit[1250]{$^{\circ}$C} for \unit[5-10]{h}.
For a critical dose, which was found to depend on the Si substrate orientation, the formation of a stoichiometric buried layer of SiC exhibiting a well-defined interface to the Si host matrix was observed.
In case of overstoichiometric C concentrations the excess C is not redistributed.
-These investigations demonstrate the presence of an upper dose limit, which corresponds to a \unit[50]{at.\%} C concentration at the implantation peak, for the thermally induced redistribution of the C atoms from a Gaussian to a box-shaped depth profile upon annealing.
-For higher concentrations the formation of strong C-C bonds is expected.
-Increased temperatures are necessary for the dissociation of these C clusters.
+These investigations demonstrate the presence of an upper dose limit, which corresponds to a \unit[53]{at.\%} C concentration at the implantation peak, for the thermally induced redistribution of the C atoms from a Gaussian to a box-shaped depth profile upon annealing.
+This is explained by the formation of strong graphitic C-C bonds for higher C concentrations \cite{calcagno96}.
+Increased temperatures exceeding the Si melting point are expected to be necessary for the dissociation of these C clusters.
Furthermore, higher implantation energies were found to result in layers of variable composition exhibiting randomly distributed SiC precipitates.
In another study \cite{serre95} high dose C implantations were performed at room temperature and \unit[500]{$^{\circ}$C} respectively.
Implantations at room temperature lead to the formation of a buried amorphous carbide layer in addition to a thin C-rich film at the surface, which is attributed to the migration of C atoms towards the surface.
Annealing at temperatures up to \unit[1150]{$^{\circ}$C} does not alter the C profile.
Instead defect annihilation is observed and the C-rich surface layer of the room temperature implant turns into a layer consisting of SiC precipitates, which, however, are not aligned with the Si matrix indicating a mechanism different to the one of the direct formation for the high-temperature implantation.
-.. lindner limit in dose -> 1250
+Based on these findings, a recipe was developed to form buried layers of single-crystalline SiC featuring an improved interface and crystallinity \cite{lindner99,lindner01,lindner02}.
+Therefore, the dose must not exceed the stoichiometry dose, i.e. the dose corresponding to \unit[50]{at.\%} C concentration at the implantation peak.
+Otherwise clusters of C are formed, which cannot be dissolved during post-implantation annealing at moderate temperatures below the Si melting point \cite{lindner96,calcagno96}.
+Annealing should be performed for \unit[5-10]{h} at \unit[1250]{$^{\circ}$C} to enable the redistribution from the as-implanted Gaussian into a box-like C depth profile \cite{lindner95}.
+The implantation temperature constitutes the most critical parameter, which is responsible for the structure after implantation and, thus, the starting point for subsequent annealing steps.
+
+
+\cite{lindner98} sharp interface and good crystallinity
+
+improved two-temperature implantation \cite{lindner99}.
+
+By understanding these basic processes
+... lindner limit in dose -> 1250
... two temp implantation ... sharp interface
By understanding some basic processes (32-36), \ac{IBS} nowadays has become a promising method to form thin SiC layers of high quality exclusively of the 3C polytype embedded in and epitactically aligned to the Si host featuring a sharp interface \cite{lindner99,lindner01,lindner02}.
\section{Assumed cubic silicon carbide conversion mechanisms}
\label{section:assumed_prec}
+... \cite{lindner99_2} ...
+
on surface ... md contraction along 110 ... kitabatake ... and ref in lindner ... rheed from si to sic ...
in ibs ... lindner and skorupa ...
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