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[en] We have investigated transport in a cross-shaped two-dimensional electron gas with superconducting electrodes coupled to two opposite arms. Multiterminal resistances, measured as a function of the superconducting phase difference and the magnetic flux, are analyzed in terms of an extended Landauer-Buettiker transport formalism. We show that extended reciprocity relations hold. Correlations between transport coefficients are obtained from, e.g., (negative) three-terminal and nonlocal resistances. Energy spectroscopy reveals a reentrant behavior of the transport coefficients around the Thouless energy. copyright 1996 The American Physical Society

[en] The interaction between point defects in the matrix and excitons localized in self-organized InGaAs/GaAs quantum dots is investigated for structures irradiated by protons. The exciton ground state is demonstrated to be unaffected by radiation doses up to 10¹⁴ p/cm². The close proximity of radiation-induced defects leads to a strong nonmonotonous temperature dependence of the luminescence yield: Carriers are lost via tunneling from excited quantum dot states to irradiation-induced defects below ∼100 K, whereas at higher temperatures, carriers escape to the barrier and are captured by defects

[en] Emission of electrons from localized electron states in InAs/GaAs self-organized quantum dots (QDs) grown by MOCVD has been studied by a combination of steady-state voltage-capacitance and admittance techniques. We have found a fine structure of carrier concentration profile in the area of QDs, which may be attributed to ground and excited energy states of electrons in the QDs. The total range of activation energies detected in the admittance investigations extends from 20 meV up to 140 meV and testifies to the significant inhomogeneous broadening of the density of state function due to the QD scattering in geometric sizes