The importance of characterising the atomic structure of the silicon / silicon dioxide interface as an essential component in highly integrated circuits has steadily increased as a result of continuing miniaturisation of silicon chips. The physicists, Dr. Stefan Bergfeld, Bjoern Braunschweig and Prof. Dr. Winfried Daum, Institute of Physics and Physical Technologies at the Technical University of Clausthal, have succeeded in characterising the change in bond structure of interfacial atoms during the oxidation of a silicon surface by a purely optical method. The results of the research have been published in the scientific journal, Physical Review Letters, Volume 93, No. 9 (online on 27th August 2004).
In the present work, the atmospheric oxidation of a hydrogen-covered (111)-oriented silicon surface has been studied, and special bonding states of the silicon atoms have been identified. The scientists also observed these bonding states after the technically relevant thermal oxidation. For characterising the interfaces, the physicists apply a special nonlinear-optical method, with which the laser light is converted by interfacial atoms to photons with energies in the near ultraviolet range by doubling of the frequency. This purely optical spectroscopic method with frequency doubling allows nondestructive characterisation of the oxidation process under real conditions and also provides very high interfacial sensitivity, in comparison with other optical methods.
The Si(111)-SiO2 interface is a prime example of an abrupt transition from a perfect crystal structure to an amorphous oxide. In contrast to the technologically more relevant Si(100) surface, the surface of a (111)-terminated silicon crystal possesses a structure consisting of bi-layers, in which changes in the bond structure resulting from oxidation can be observed especially well.
Winfried Daum | alfa
Computer model predicts how fracturing metallic glass releases energy at the atomic level
20.07.2018 | American Institute of Physics
What happens when we heat the atomic lattice of a magnet all of a sudden?
18.07.2018 | Forschungsverbund Berlin
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
20.07.2018 | Power and Electrical Engineering
20.07.2018 | Information Technology
20.07.2018 | Materials Sciences