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Excitons in core-shell nanowires with polygonal cross sections

Excitons in core-shell nanowires with polygonal cross sections

Title: Excitons in core-shell nanowires with polygonal cross sections
Author: Sitek, Anna   orcid.org/0000-0002-0602-1959
Urbaneja Torres, Miguel   orcid.org/0000-0002-9342-988X
Torfason, Kristinn
Gudmundsson, Vidar   orcid.org/0000-0001-8939-3522
Bertoni, Andrea
Manolescu, Andrei   orcid.org/0000-0002-0713-4664
Date: 2018-04-21
Language: English
Scope: 2581-2589
University/Institute: Háskólinn í Reykjavík
Reykjavik University
Háskóli Íslands
University of Iceland
School: Tækni- og verkfræðideild (HR)
School of Science and Engineering (RU)
Verkfræði- og náttúruvísindasvið (HÍ)
School of Engineering and Natural Sciences (UI)
Department: Raunvísindastofnun (HÍ)
Science Institute (UI)
Series: Nano Letters;18(4)
ISSN: 1530-6984
1530-6992 (eISSN)
DOI: 10.1021/acs.nanolett.8b00309
Subject: Core−shell nanowires; Excitons; Localization; Polygonal cross sections; Nanótækni; Eðlisfræði; Rúmfræði
URI: https://hdl.handle.net/20.500.11815/694

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Sitek, A., Urbaneja Torres, M., Torfason, K., Gudmundsson, V., Bertoni, A., & Manolescu, A. (2018). Excitons in Core–Shell Nanowires with Polygonal Cross Sections. Nano Letters, 18(4), 2581-2589. doi:10.1021/acs.nanolett.8b00309


The distinctive prismatic geometry of semiconductor core-shell nanowires leads to complex localization patterns of carriers. Here, we describe the formation of optically active in-gap excitonic states induced by the interplay between localization of carriers in the corners and their mutual Coulomb interaction. To compute the energy spectra and configurations of excitons created in the conductive shell, we use a multi-electron numerical approach based on the exact solution of the multi-particle Hamiltonian for electrons in the valence and conduction bands, which includes the Coulomb interaction in a nonperturbative manner. We expose the formation of well separated quasidegenerate levels, and focus on the implications of the electron localization in the corners or on the sides of triangular, square and hexagonal cross sections. We obtain excitonic in-gap states associated with symmetrically distributed electrons in the spin singlet configuration. They acquire large contributions due to Coulomb interaction, and thus are shifted to much higher energies than other states corresponding to the conduction electron and the vacancy localized in the same corner. We compare the results of the multi-electron method with those of an electron-hole model and we show that the latter does not reproduce the singlet excitonic states. We also obtain the exciton lifetime and explain selection rules which govern the recombination process.


Copyright © 2018 American Chemical Society

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