micropipe / new refs

[lectures/latex.git] / posic / thesis / sic.tex

diff --git a/posic/thesis/sic.tex b/posic/thesis/sic.tex
index 55d04fc..34c1256 100644 (file)
--- a/posic/thesis/sic.tex
+++ b/posic/thesis/sic.tex
@@ -157,7 +157,10 @@ The porous material constitutes a severe source of contamination, e.g. with the
 Since the vapor pressure of Si is much higher than that of C, a careful manipulation of the Si vapor content above the seed crystal is required.
 Additionally, to preserve epitaxial growth conditions, graphitization of the seed crystal has to be avoided.
 Avoiding defects constitutes a major difficulty.
-These defects include growth spirals (stepped screw dislocations), subgrain boundaries and twins as well as micropipes (micron sized voids extending along the c axis of the crystal) and 3C inclusions at the seed crystal in hexagonal growth systems.
+These defects include growth spirals (stepped screw dislocations), subgrain boundaries and twins as well as micropipes (micron sized voids extending along the
+%c axis of the crystal)
+core of screw dislocations)~\cite{frank51,heindl97}
+and 3C inclusions at the seed crystal in hexagonal growth systems.
 Micropipe-free growth of 6H-SiC has been realized by a reduction of the temperature gradient in the sublimation furnace resulting in near-equilibrium growth conditions in order to avoid stresses, which is, however, accompanied by a reduction of the growth rate~\cite{schulze98}.
 Further efforts have to be expended to find relations between the growth parameters, the kind of polytype and the occurrence and concentration of defects, which are of fundamental interest and might help to improve the purity of the bulk materials.