Materials World Network: Electron-lattice dynamics at an atomically controlled buried interface

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The internal interface between two semiconductors consists of chemical bonds and electronic states that can differ distinctively from those of the bulk and the surface of the materials. In the framework of this project we plan to investigate the dynamics of vibrational excitations associated with such an interface by means of time-resolved, coherent phonon spectroscopy. GaP/Si(001) will serve as a model system. The polar semiconductor GaP and the non-polar semiconductor Si have similar lattice constants but different electronic and phononic properties. The main project aims are the experimental detection of interface-specific vibrational excitations and the correlation of their properties with the atomic structure of the interface. The latter will be modified and controlled by different parameters during the epitaxial growth and it will be structurally characterized with atomic resolution by scanning transmission electron spectroscopy. Coherent phonon spectroscopy is particularly well suited to investigate the dynamical coupling of electronic and phononic excitations. It is thus expected that the planned experiments will also provide interesting information about the dynamics of electronic excitations and charge transfer processes at buried, internal semiconductor interfaces.