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The Institute
The 1994 founded IALB focuses on
electrical drives, mechatronics, an-
drenewable energy (Prof. Bernd Orlik)
and on power semiconductor compo-
nents, their environment, and applica-
tions (Prof. Nando Kaminski, details see
below). Both fields are members of the
Bremen Center of Mechatronics (BCM,
see
).
Semiconductor Basics
Basic semiconductor physics and proper-
ties are investigated and modelled. A spe-
cial focus is on alternative semiconductor
materials like silicon carbide (SiC) and gal-
lium nitride (GaN), which play an increas-
ingly important role in power semiconduc-
tor devices. The IALB operates a deep level
transient spectroscopy (DLTS) and admit-
tance spectroscopy equipment.
Device Concepts
The optimisation of existing components,
the investigation of new concepts, and
the modelling of devices are carried out
by means of simulation and in coopera-
tion with leading semiconductor manu-
facturers e.g. Infineon and ABB. Examples
for current activities are the investigation
of the RC-IGBT with respect to turn-off,
snap-back, and diode behaviour as well as
the investigation of a novel device concept
for DC-switches. For semiconductor simu-
lation Sentaurus of Synopsis Inc. is used, if
necessary in mixed mode with circuit and
thermal simulation.
Packaging and Reliability
Housing technology and cooling affect
the reliability of semiconductor devices
significantly. A current core activity of the
IALB is the investigation of IGBT modules
under humidity, temperature and high bias.
Test facilities for climate and load cycling
are available. Another very important
aspect of the packaging is parasitics.
The determination of such components
is done by means of measurement and
simulation (ANSYS-Q3D by Ansoft Corp.),
respectively.
Application
The focus with respect to applications is
on the interaction between circuitry and
devices. One activity is IGBTs used for res-
onant switching. With rising switching
speed and frequencies especially with SiC
and GaN devices parasitics play an increas-
ingly important role and affect the EMC-
performance considerably. This is inves-
tigated by simulation and measurements
e.g. double pulse testing.
University of Bremen
Institute for Electrical Drives, Power Electronics, and Devices (IALB)
Fig.1 – Over current breaker based on the dual thyristor principle but realised with MOSFETs and a SiC JFET in
cascode configuration
Fig.2 – Aluminium corrosion mechanism and
degradation found in the failure analysis after
humidity testing
