Optoelectronic Materials, and semiconductors in particular, constitute the building blocks for most of today's high-tech gadgets and instruments. But beyond that, they present us with unique insights into materials properties, due to their extreme sensitivity to even the slightest changes of composition. The central role of chemistry in conducting both goal-oriented and curiosity-driven research in this area is obvious: only through chemistry can we hope to change and control composition. For the "common" or "classical" materials such as Si, GaAs, InP, much of their chemistry has been known for years. At least so it was thought…..

The majority of the common semiconductor materials are not composed of the molecules with which most chemists are familiar, but rather of a near-infinite network of atoms, so-called extended bonding. Such networks have specific structures and the properties of the solid depend critically on that structure. Changing the composition of the solid to change its properties is then possible only within certain generally narrow limits, as the original structure needs to be preserved. This leads to changing the surface as an additional degree of freedom.

Our work can, roughly speaking, be divided into surface-/interface-related and bulk material-related.