Deliverables and Services - IHP Microelectronics

90 A n n u A l R e p o R t 2 0 0 9
e r S C H I e N e N e p u B L I K A t I o N e N – p u B L I S H e d p A p e r S
(39) on the Band Gaps and electronic Structure
of thin Single Crystalline praseodymium
oxide Layers on Si(111)
o. Seifarth, J. Dabrowski, p. Zaumseil,
S. Müller, D. Schmeißer, H.-J. Müssig,
t. Schroeder
Journal of Vacuum Science and technology B
27, 271 (2009)
the influence of stoichiometry and crystal structure
on the electronic properties of single crystalline
cubic pro 2 (111), cubic pr 2 o 3 (111), and hexagonal
pr 2 o 3 (0001) thin film heterostructures on Si(111) was
investigated by synchrotron radiation based photoemission
electron spectroscopy (peS) and x-ray absorption
spectroscopy (XAS). A detailed analysis of
the complex satellite structures of peS pr 3d lines of
the various pr oxide phases is given. peS was in addition
applied to study the o 2p derived valence band
structure and the positions of the occupied pr 4f state
density. It is found by a combined peS-XAS study that
especially the band gap values strongly depend on the
stoichiometry and crystal structure of the single crystalline
pr oxide layer. Furthermore, the close structure
relationship between cubic pr 2 o 3 (111) and pro 2 (111)
films is probably the reason for the detection of nonstoichiometric
behavior, an effect which is far less
pronounced in case of hexagonal pr 2 o 3 (0001) layers.
A possible origin of this effect is given by a surface
modified valence change and therefore of importance
to understand in future the epitaxial overgrowth of
these oxide buffer heterostructures by alternative semiconductors
such as germanium.
(40) Synchrotron Microscopy and Spectroscopy
for Analysis of Crystal defects in Silicon
W. Seifert, o. Vyvenko, t. Arguirov, A. erko,
M. Kittler, C. Rudolf, M. Salome, M. trushin,
I. Zizak
physica Status Solidi C 6, 765 (2009)
the paper discusses the synchrotron-based microprobe
techniques XBIC (X-ray beam induced current), -
XRF (X-ray fluorescence microscopy) and -XAS (X-ray
absorption microspectroscopy) and their application
for studying electrical activity of defects and preci-
pitation of transition metals in Si materials. Investigations
were performed on samples of block-cast
multicrystalline Si and on model samples cut from a
bonded monocrystalline wafer. to analyze the precipitation
sites, ni, Cu and Fe were introduced intentionally
into the samples. the detected precipitates
were found to consist of silicides. evidence for metal
precipitates was also found in virtually uncontaminated
as-grown block-cast Si. Besides ni precipitates
detected at a recombination active grain boundary,
particles containing one or several metals (Cu, Fe, ti,
V) were observed. unexpectedly, these particles seem
to exhibit low only recombination activity. Further
studies are necessary to identify their nature.
(41) Synchrotron-based Investigation of Iron
precipitation in Multicrystalline Silicon
W. Seifert, o. Vyvenko, t. Arguirov, M. Kittler,
M. Salome, M. Seibt, M. trushin
Superlattices and Microstructures 45, 168
(2009)
We report on investigations of the precipitation of
iron in block-cast multicrystalline silicon using the
techniques of X-ray beam induced current, X-ray fluorescence
microscopy and X-ray absorption microspectroscopy.
the samples studied were intentionally
contaminated with iron and annealed at temperatures
between 850 and 1050 °C. Annealing at 950 °C was
found to lead to well detectable iron precipitation
inside the grains and at grain boundaries. Small only
iron clusters were detected after the 850 °C anneal
while no iron clusters were found after the 1050 °C
treatment. X-ray absorption near edge structure analyses
of the iron clusters revealed mostly iron silicide
and in one case iron oxide. under the given condition
at the beamline, the detection sensitivity for iron
was estimated to be 4×10 7 atoms, corresponding to a
spherical FeSi 2 particle of 40 nm radius.