Research of the Weber Group
The objective
of our research is the analysis and control of defects in semiconductors
to improve our fundamental understanding of these defects and
to ultimately improve the performance of electronic and opto-electronic
semiconductor devices. We perform thin film growth by MBE, processing
of simple device structures in the UC microlab, and in-depth
structural, electrical, optical and magnetic resonance characterization
of semiconductor materials and device structures. Most projects
involve collaborations with industry.
Our research group is organized in four teams, with most teams
including a postdoctoral scientist or Research Associate, graduate
students and undergraduate aids.
For an overview, see
E.R. Weber's ICDS talk.
Research
of the Si team is currently concentrated on the study of transition
metal contamination and radiation damage in Si crystals and
device structures for IC and photovoltaic applications. Our
research on Si for IC applications is part of the Silicon Wafer
Engineering and Defect Science (SiWEDS) consortium. The research
on Si for photovoltaic applications is part of a team of University
groups sponsored by the National Renewable Energy Lab (NREL).
Part of this research is performed at the synchrotron in LBNL
(Advanced Light Source, ALS).
Further
info:
Dr. Andrei Istratov istratov@socrates.berkeley.edu.
The research
of this team is concerned with the growth and analysis of thin
films of GaAs and GaAsN, most of them grown by MBE. One topic
of great interest has been the investigation of GaAs deposited
by MBE at low temperature, down to 200°C (Low temperature
grown -GaAs). This material has a high concentration of excess
As that results in ultrashort carrier lifetime and semi-insulating
properties. Doped LT-GaAs can have carrier concentrations much
higher then usually possible in GaAs grown by MBE at higher
temperatures. Recently, the research interest of this team turned
to the deposition of In(Ga)As quantum dot structures and (In)GaAsN
layers with small bandgap for applications in the optical communication
area (1.3 and 1.5 µm). Another focal point are defects
formed upon oxidation of ultrathin layers of AlAs.
Further
info:
Dr. Petra Specht, specht@socrates.Berkeley.EDU
This research
team concentrated on the investigation of GaN thin films, InGaN
quantum wells, and recently ZnO nanowire structures for blue
and white light emitting devices and high-speed optoelectronics.
Studies of MBE growth of GaN on different substrates and with
novel buffer layers is part of this research. An important issue
of recent interest is the quantitative analysis of the influence
of polarization-induced charge separation and inhomogeneity-induced
charge localization in InGaN/GaN quantum well structures for
commercial blue and white LEDS.
Further
info:
Dr. Petra Specht, specht@socrates.Berkeley.EDU
We are studying
III/V semiconductors and semiconductor heterostructures by cross-sectional
scanning tunneling microscopy (X-STM) and STM-induced cathodo-luminescence
(STM-CL). The STM-CL studies are done in a system that allows
investigations down to LHe temperature.
