puh ...

diff --git a/posic/thesis/sic.tex b/posic/thesis/sic.tex
index c2fd285..6eacee9 100644 (file)
--- a/posic/thesis/sic.tex
+++ b/posic/thesis/sic.tex
@@ -120,16 +120,16 @@ The presented methods, thus, focus on vapor transport growth processes such as c
 \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 (coal).
+The heating is accomplished by a core of graphite centrally placed in the furnace, which is heated up to a maximum temperature of \unit[2700]{$^{\circ}$C}, after which the temperature is gradually lowered.
 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.
-Missing: temperature, some of the material good for electronic device production.
 
 In the van Arkel apparatus \cite{arkel25}, Si and C containing gases like methylchlorosilanes \cite{moers31} and silicon tetrachloride \cite{kendall53} are pyrolitically decomposed and SiC is deposited on heated carbon rods in a vapor growth process.
 Typical deposition temperatures are in the range between \unit[1400]{$^{\circ}$C} and \unit[1600]{$^{\circ}$C} while studies up to \unit[2500]{$^{\circ}$C} have been performed.
 The obtained polycrystalline material consists of small crystal grains with a size of several hunderd microns stated to be mainly of the cubic polytype.
 
 A significant breakthrough was made in 1955 by Lely, who proposed a sublimation process for growing higher purity bulk SiC single crystals \cite{lely55}.
-In the so called Lely process, 
+In the so called Lely process, a tube of porous graphite is surrounded by polycrystalline SiC as gained by previously described processes.
 Lely (sublimation)
 
 modified Lely or modified sublimation