Cel
Groups from different countries in the NIS and western Europe will undertake a coherent investigation of the influence of the surface on electronic excitations in low-dimensional semiconductors systems. Up to now the properties of excitonic transitions in quantum wells, quantum wires and quantum dots have been discussed predominantely on the basis of a pure semiconductor picture. However, very often the low-dimensional structures are located in close proximity to a surface (e.g. quantum wells with thin barriers) or may even be defined by a surface (etched quantum wires and dots). In these structures the replacement of the semiconductor band discontinuities by the much larger electron affinity, the strong change of the dielectric constant and surface mediated recombination channels are expected to control the excitonic transitions to a large degree.
Based on samples made at Würzburg University, magnetoluminescence investigations will be carried out at the Institute for Solid State Physics, Chernogolovka, which should enable the influence of the surface to be varied via the magnetic field. At the Physics Institute, Kiev University, the emission involving the spin split valence band will be investigated. By using magneto Raman experiments the strain as well as the electronic and vibronic properties will be analyzed at the Universidad Autonoma of Madrid. A theoretical description of electronic states, optical transitions and electron scattering in surface controlled low-dimensional semiconductor structures will be developed at the Ecole Normale Supérieure in Paris. At Moscow State University surface exciton polaritons will be modelled as well as the possibilities for the observation of an excitonic crystal. The group at the University of Rome will investigate hydrogen passivation effects for surface controlled semiconductor structures. Ultra high spatial resolution studies of the field distribution in quantum wire and dot structures will be performed at the University of Basel. Theoretical studies of the electromagnetic field distribution and polarization effects will be carried out at the General Physics Institute, Moscow. Experiments and theory will be carried out in very close collaboration.
Temat(-y)
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97074 Würzburg
Niemcy