Cone-Shell Quantum Structures in Electric and Magnetic Fields as Switchable Traps for Photoexcited Charge Carriers.

Nanomaterials (Basel)

Grupo de Materia Condensada-UdeA, Instituto de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Antioquia UdeA, Calle 70 No. 52-21, Medellín AA 1226, Colombia.

Published: May 2023

The optical emission of cone-shell quantum structures (CSQS) under vertical electric () and magnetic () fields is studied by means of simulations. A CSQS has a unique shape, where an electric field induces the transformation of the hole probability density from a disk into a quantum-ring with a tunable radius. The present study addresses the influence of an additional magnetic field. A common description for the influence of a -field on charge carriers confined in a quantum dot is the Fock-Darwin model, which introduces the angular momentum quantum number to describe the splitting of the energy levels. For a CSQS with the hole in the quantum ring state, the present simulations demonstrate a -dependence of the hole energy which substantially deviates from the prediction of the Fock-Darwin model. In particular, the energy of exited states with a hole lh> 0 can become lower than the ground state energy with lh= 0. Because for the lowest-energy state the electron le is always zero, states with lh> 0 are optically dark due to selection rules. This allows switching from a bright state (lh= 0) to a dark state (lh> 0) or vice versa by changing the strength of the or field. This effect can be very interesting for trapping photoexcited charge carriers for a desired time. Furthermore, the influence of the CSQS shape on the fields required for the bright to dark state transition is investigated.

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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC10221091PMC
http://dx.doi.org/10.3390/nano13101696DOI Listing

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