Extended excitons and compact helium-like biexcitons in type-II quantum dots - Condensed Matter > Mesoscale and Nanoscale PhysicsReport as inadecuate




Extended excitons and compact helium-like biexcitons in type-II quantum dots - Condensed Matter > Mesoscale and Nanoscale Physics - Download this document for free, or read online. Document in PDF available to download.

Abstract: We have used magneto-photoluminescence measurements to establish thatInP-GaAs quantum dots have a type-II staggered band alignment. The averageexcitonic Bohr radius and the binding energy are estimated to be 15nm and 1.5meV respectively. When compared to bulk InP, the excitonic binding is weakerdue to the repulsive type-II potential at the hetero-interface. Themeasurements are extended to over almost six orders of magnitude of laserexcitation powers and to magnetic fields of up to 50 tesla. It is shown thatthe excitation power can be used to tune the average hole occupancy of thequantum dots, and hence the strength of the electron-hole binding. Thediamagnetic shift coefficient is observed to drastically reduce as the quantumdot ensemble makes a gradual transition from a regime where the emission isfrom hydrogen-like two-particle excitonic states to a regime where theemission from helium-like four-particle biexcitonic states also becomesignificant.



Author: Bhavtosh Bansal, S. Godefroo, M. Hayne, G. Medeiros- Ribeiro, V. V. Moshchalkov

Source: https://arxiv.org/



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