One of the main objectives of our work is to analyse electronic and
optical properties of semiconductor and metal surfaces. To measure in
situ (during growth) instead of ex situ (after growth)
optical methods such as Reflectance Anisotropy Spectroscopy (RAS),
Spectroscopic Ellipsometry (SE), Raman Spectroscopy and
Magneto-Optical Kerr Spectroscopy (MOKE) are used. Complementary
information is also gained in Ultra-High Vacuum (UHV) by Scanning
Tunneling Microscopy (STM), Photo-Emission Spectroscopy (PES), Low
Energy Electron Diffraction (LEED), and Auger Electron Spectroscopy
(AES).
This
combination makes it possible to monitor the surface in situ
with optical tools. On the other hand, Raman, RAS and SE spectra are
being influenced by other parameters (morphology, composition,
doping) that provide information UHV based tools cannot obtain
easily. Also the interaction between local structure (STM) and log
range order (LEED) is part of these investigation. The newest
addition are MOKE (analysis of magnetic layers), Infrared
Spectroscopy (FTIR), and true in-situ
Atomic Force Microscopy (AFM) is in preparation.
The aim is to understand
growth of new materials like InGaN or ferromagenetic semiconductors.
On the other hand for III-V semiconductors like GaInAsP to control
layer properties like roughness, to control size and density of
quantuum dots by a feedback from the in-situ measurements to the
growth process.
Schematic setup of an in-situ MOVPE reactor.
Contact:
- Wolfgang Richter (General Coordination)
- Markus Pristovsek, Florian Poser, Stefan Weeke (III-V MOVPE)
- Torsten Schmidtling, Massimo Drago (Nitride)
- Christian Kaspari, Eugen Speiser, Bert Rähmer (in-situ technology)
Collaboration:
Research projects:
