Deliverables and Services - IHP Microelectronics

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
pr 2 o 3 (111) / Si(111) heterostructure, a result also
corroborated by theoretical ab initio structure calculations.
Secondary ion mass spectroscopy confirms
the absence of pr and Si impurities in the Ge(111)
epilayer, even after an annealing at 825 °C.
(15) defect Structure of Ge(111) / Cubic
pr 2 o 3 (111) / Si(111) Heterostructures:
thickness and Annealing dependence
A. Giussani, p. Zaumseil, p. Rodenbach,
G. Weidner, M.A. Schubert, D. Geiger,
H. lichte, p. Storck, J. Wollschläger,
t. Schroeder
Journal of Applied physics 106, 073502
(2009)
the defect structure of Ge(111) epilayers grown by
molecular beam epitaxy on cubic pr 2 o 3 (111) / Si(111)
support systems was investigated by means of transmission
electron microscopy and laboratory-based
x-ray diffraction techniques. three main types of defects
were identified, namely, rotation twins, microtwins,
and stacking faults, and studied as a function
of Ge film thickness and after annealing at 825 °C in
ultrahigh vacuum. Rotation twins were found to be
localized at the Ge(111) / cubic pr 2 o 3 (111) interface
and their amount could be lowered by the thermal
treatment. Microtwins across {111} were detected
only in closed Ge films, after Ge island coalescence.
the fraction of Ge film volume affected by microtwinning
is constant within the thickness range of ~20–
260 nm. Beyond 260 nm, the density of microtwins
is clearly reduced, resulting in thick layers with a top
part of higher crystalline quality. Microtwins resulted
insensitive to the postdeposition annealing. Instead,
the density of stacking faults across {111} planes
decreases with the thermal treatment. In conclusion,
the defect density was proved to diminish with increasing
Ge thickness and after annealing. Moreover, it
is noteworthy that the annealing generates a tetragonal
distortion in the Ge films, which get in-plane
tensely strained, probably due to thermal mismatch
between Ge and Si.
(16) All-optical wavelength Conversion at
160 GBit / s using an SoA and a Silicon-on-
Insulator photonic Circuit
F. Gomez-Agis, o. Raz, S.J. Zhang,
e. tangdiongga, l. Zimmermann, K. Voigt,
C. Vyrsokinos, l. Stampoulidis, H.J.S. Dorren
electronics letters 45(22), 1132 (2009)
error-free operation of an all-optical wavelength converter
at 160 Gbit / s based on a semiconductor optical
amplifier and a silicon-on-insulator photonic circuit,
consisting of two cascaded Mach-Zehnder delay
interferometers, is demonstrated.
(17) Micro-photoluminescence Spectroscopy
on Metal precipitates in Silicon
p. Gundel, M.C. Schubert, W. Kwapil, J. Schön,
M. Reiche, H. Savin, M. Yli-Koski, J.A. Sans,
G. Martinez-Criado, W. Seifert, W. Warta,
e.R. Weber
physica Status Solidi (RRl)-Rapid Research
letters 3, 230 (2009)
Metallic impurities are detrimental to many silicon
devices and limit the efficiency of multicrystalline silicon
solar cells. therefore they are a major subject of
ongoing research. photoluminescence spectroscopy
is a promising technique for detecting precipitated
metals in silicon because of its sensitivity to the minority
carrier density and to specific types of defects;
however the impact of impurities on the defect luminescence
could not be clarified yet. In this letter we
examine the role of micron-sized iron and copper precipitates
in direct bonded wafers by micro-photoluminescence
spectroscopy. Both kinds of precipitates
are detectable by means of the reduced band-to-band
luminescence. An element-specific effect on the defect
luminescence is observed. the results are confirmed
by X-ray fluorescence spectroscopy.
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