Friday 15 November 2019, 3:00pm to 4:00pm
Open toAlumni, Postgraduates, Staff, Undergraduates
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Theory of single- and multi-particle states of semiconductor nanostructures
In this talk I will first briefly describe the theory of single-particle quantized states ( k.p/envelope function methods) and their useage as basis states for the full configuration interaction method (CI) , which enables to obtain detailed and rich information about the multi-particle electronic structure of the studied material. Thereafter, several systems of semiconductor nanostructures will be discussed, each of those necessitating different level of complexity of the physical picture, in order to obtain reasonable fidelity between the model and experimental results. Those will range from InGaAs/GaAs quantum dots (QDs)  without or with GaAsSb overlayer  showing spatially direct (type-I) or indirect (type-II) transition between electrons and holes, respectively. The model will then be expanded to describe also CI states with momentum k-indirect transitions such as SiGe/Si  and InGaAsSb/GaAs/GaP QDs . Furthermore, two prominent systems will receive more attention due to their intriguing properties. Those are GaSb/GaAs quantum rings  and GaAs/AlGaAs lattice matched QDs , and tentative results for such systems are shown in figures below. The former system is of type-II nature strongly confining holes, leading to the pronounced emission of CI complexes consisting of considerably more holes than electrons (positive trions). On the other hand, the quasiparticles are weakly confined in the latter system, which leads to exotic phenomena such as considerably increased radiativeemission of excitons or anomalous diamagnetic shift of excited trion states.
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|Name||Dr Sergey Kafanov|