Deliverables and Services - IHP Microelectronics

80 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
grated intensity of the band at 985 cm -1 using the
known calibration factor for interstitial oxygen.
(4) SiGe Analog AGC Circuit for an 802.11a
wLAN direct Conversion receiver
J.p. Alegre, S. Celma, B. Calvo, n. Fiebig,
S. Halder
Ieee transactions on Circuits and Systems II
56(2), 93 (2009)
this brief presents a baseband automatic gain control
(AGC) circuit for an Ieee 802.11a wireless local area
network (WlAn) direct conversion receiver. the whole
receiver is to be fully integrated in a low-cost 0.25
µm 75-GHz SiGe bipolar complementary metal-oxidesemiconductor
(BiCMoS) process; thus, the AGC has
been implemented in this technology by employing
newly designed cells, such as a linear variable gain
amplifier (VGA) and a fast-settling peak detector. Due
to the stringent settling-time constraints of this system,
a feedforward gain control architecture is proposed
to achieve fast convergence. the proposed AGC is
composed of two coarse-gain stages and a fine-gain
stage, with a feedforward control loop for each stage.
It converges with a gain error of below ± 1dB in less
than 3.2 µs, whereas the power and area consumption
are 13.75 mW and 0.225 mm 2 , respectively.
(5) Laser Annealing of the Si Layers in
Si / Sio 2 Multiple Quantum wells
t. Arguirov, t. Mchedlidze, S. Kouteva-
Arguirova, M. Kittler, R. Roelver, B. Berghoff,
D. Bätzner, B. Spangenberg
Materials Science and engineering B
159-160, 57 (2009)
the transition of amorphous to crystalline silicon
in nanometer-sized structures was investigated by
means of Raman spectroscopy. the phase transition
was induced by illumination with monochromatic
light. the crystallization and accompanying processes
were studied for silicon layers embedded in
silicon oxide matrix and forming a multiple quantum
well (MQW) structure. thickness of the layers varied
in 3–60 nm range for various MQW. the results could
be explained considering dispersion in light absorpti-
on of amorphous and crystalline films for the employed
range of radiation wavelengths. the electrical and
photovoltaic properties of the crystallized structures
were characterized in view of their capability for lateral
carrier transport.
(6) Silicon Based Light emitters utilizing
radiation from dislocations: electric Field
Induced Shift of the dislocation-related
Luminescence
t. Arguirov, t. Mchedlidze, M. Kittler,
M. Reiche, t. Wilhelm, t. Hoang, J. Hollemann,
J. Schmitz
physica e 41, 907 (2009)
Dislocation rich regions can be controllably formed at
a certain location inside a silicon wafer. We studied
the light emission properties of such regions located
in an electric field of a p-n junction under different
excitation conditions. It was found that the luminescence
spectra of the dislocations are significantly
influenced by the presence of the junction. the dislocation-related
luminescence peak position appears
red-shifted due to the built-in electric field. A suppression
of that field by photo-generation of carriers
or by applying a forward bias voltage at the junction
leads to a gradual decrease in the energy position of
the peaks. the dependence of the peak position on
the electric field was found to be a quadratic function,
similar to that observed for semiconductor nanostructures.
We show that the shift of the peak position
is due to the Stark effect on dislocation-related
excitonic states. the characteristic constant of the
shift, obtained by fitting the data with the quadratic
Stark effect equation, was 0.0186 meV / (kV / cm) 2 .
the observed effect opens new possibilities for integration
of a silicon based light emitter, combining
the radiation from dislocations with a Stark effect
based modulator.