Institute of Solid-State Physics

Prof. Dr. Wolfgang Richter

02.01.1940 - 12.02.2013

Professor Dr. Wolfgang Richter worked at the Institute of Solid State Physics at the Technical University of Berlin from 1988 until his retirement in 2005.

Through his work, Professor Dr. Wolfgang Richter had a decisive influence on the Institute of Solid State Physics and many generations of scientists. His scientific work led to new, fundamental insights in the field of surface as well as interfacial optics and contributed significantly to the industrial application of optical in-situ spectroscopy. For his academic work he has received numerous honors in Germany and abroad.

We held Wolfgang Richter in high esteem as a university teacher, as a scientist, and especially as a person, and will always honor his memory.

After a prolonged illness, our esteemed colleague and former mentor Wolfgang Richter passed away in Rome in February 2013 at the age of 73. Since our time as his first generation diploma and PhD students, we were connected with him not only by the fact that we learned to "walk" scientifically under his guidance, but also by an ongoing scientific cooperation and personal friendship.

His main field of work and scientific "love" was solid-state optics - especially at interfaces and surfaces. Already in his doctoral studies at the University of Cologne, he dealt with infrared spectroscopy on tellurium. In his subsequent postdoctoral years with Elias Burstein (Philadelphia) and Manuel Cardona at the MPI for Solid State Research (Stuttgart), resonant Raman spectroscopy on compound semiconductors became the focus of his interest. After his habilitation with Peter Grosse (RWTH Aachen), he deepened this topic as a professor at the University of Ulm and at RWTH Aachen (1979-88). In this context, epitaxial layer systems played an increasingly important role. Soon, the goal crystallized that was to shape Wolfgang Richter's research career until the end: the optical analysis of surfaces and the direct in situ observation of growth processes of epitaxial III-V semiconductor layers. Added to this was the development of metal-organic gas-phase epitaxy at RWTH Aachen University. But little was known about the complex processes in the gas phase and especially on the substrate surface that should lead from gaseous precursors to crystalline GaAs. Bringing both together required solving a classical problem in surface physics: surface analysis under non-UHV conditions.

The appointment to a C4 professorship at the TU Berlin in 1988 allowed Wolfgang Richter to tackle both sides of the problem simultaneously: both to optically characterize surfaces in UHV as a reference and to develop in situ optical tools that can follow gas phase epitaxy growth processes in real time and reveal the evolution of surface structure and morphology. Over the 20 or so years of his work in Berlin, this approach has made a big difference. Clearly shown today in many examples is how ellipsometry, Raman spectroscopy, and especially reflection anisotropy spectroscopy can be used to spectroscopically analyze elementary surface excitations. Advances in "computational material science" allow these spectral fingerprints to be translated into atomic structural information. The in-situ optical sensors are nowadays a standard option in commercial MOVPE reactors.

In addition to science, Wolfgang Richter was also interested in people and their living conditions. Early on, he cultivated scientific contacts in the former GDR, which he was able to expand further after the opening of the Wall. Cooperations with colleagues at the HU Berlin, the FSU Jena (especially Friedhelm Bechstedt), the Academy of Sciences in Adlershof as well as to Dresden, Leipzig and Halle were established and contributed over the years to a deeper understanding of surface optics and to the continuous development of MOVPE.

In addition, he dedicated himself in various functions to the shaping of the German and Berlin research landscape, in times of upheaval and reunification a great organizational, but especially also human task. Since 1992 he was a member and later chairman of the Berliner Physikalische Gesellschaft (Berlin Physical Society) and helped to build up this tradition-rich section in reunified Berlin. As chairman of the board of trustees of the Magnushaus he was successfully engaged in its preservation. In 1995, he organized the large festive conference for the 150th anniversary of the DPG.

After his retirement in Berlin (2005), Wolfgang Richter accepted a professorship at the University of Rome Tor Vergata, where he worked with Rudolfo DelSole, a long-time partner in theoretical solid-state optics. Here he devoted himself again to his first love: Raman spectroscopy on surfaces and thin organic layers, and that with the highest possible spatial resolution.

The illness that caused Wolfgang Richter's death in February had been bothering him for several years. But he never let it get him down - as long as there was coffee and a pipe within reach and a physical problem to discuss. His scientific work not only led to new fundamental findings, but optical in-situ monitoring has also become a hopeful concept thanks to him and his colleagues. We always appreciated the uncomplicated, open and friendly working atmosphere in his group. We miss him very much.

Norbert Esser, Jean Geurts und Dietrich RT Zahn