Papers by Author: A. Zehe

Abstract: Nanoscale metallic wires play a pivotal role in future microelectronics. Extremely high current densities, present in silicon-based integrated circuits, cause wire destruction by electron-wind induced atomic migration and void formation. In the present paper we elaborate a theoretical model, which describes the interaction of impurity-vacancy pairs. Criteria are given for an optimum material selection, based on the atomic valence of matrix and alloying metal, which reduce (or enhance) the probability of void formation.

Abstract: A new kind of a bound state has been identified at strong external excitation levels in semiconductors with high amphoteric doping, which is formed of a close donor-acceptor molecule and a neighboring second donor and/or acceptor. The recombination behavior of such a bound state is best described by AUGER-type transitions, reason for which this state is called an AUGER molecule. We have determined the existence region of such molecules in silicon-doped Ga1-xAlxAs with respect to excess carrier density and temperature by means of electron-beam excited luminescence spectroscopy at low and medium temperatures. The donor-acceptor pair radiation intensity is affected in a characteristic manner by the existence of the AUGER molecule state at elevated excitation levels and not too low temperatures. A computerized model calculation of corresponding rate coefficients turns out to be in good agreement with experimental results.

Abstract: For the modeling of erythrocyte rouleaux we develop an approximation procedure for the dipole moment in short cylinders, which contains the case of ellipsoidal bodies only as a first approximation, but allows to include corrections for short cylinders, more representative for such particles. In dependence on the number of erythrocytes forming an aggregation, i.e. on different but discrete measures of rouleaux lengths, the dielectrophoretic force is calculated and represented against the frequency of the applied a.c. field. Predictions of frequency regions in the range of 107 to 108 Hz are made, where the amount and the direction of dielectrophoresis forces is different for different rouleaux sizes.