Recently, it was shown that lasing from epitaxial Ge quantum dots (QDs) on Si substrates can be obtained if they are partially amorphized by Ge ion bombardment (GIB). Here, we present a model for the microscopic origin of the radiative transitions leading to enhanced photoluminescence (PL) from such GIB-QDs. We provide an energy level scheme for GIB-QDs in a crystalline Si matrix that is based on atomistic modeling with Monte Carlo (MC) analysis and density functional theory (DFT). The level scheme is consistent with a broad variety of PL experiments performed on as-grown and annealed GIB-QDs. Our results show that an extended point defect consisting of a split-[110] self-interstitial surrounded by a distorted crystal lattice of about 45 atoms leads to electronic states at the Γ-point of the Brillouin zone well below the conduction band minimum of crystalline Ge. Such defects in Ge QDs allow direct transitions of electrons localized at the split-interstitial with holes confined in the Ge QD. We identify the relevant growth and annealing parameters that will let GIB-QDs be employed as an efficient laser active medium

Laser level scheme of self-interstitials in epitaxial Ge dots encapsulated in Si / Grydlik, Martyna; Lusk, Mark T.; Hackl, Florian; Polimeni, Antonio; Fromherz, Thomas; Jantsch, Wolfgang; Schäffler, Friedrich; Brehm, Moritz. - In: NANO LETTERS. - ISSN 1530-6984. - 16:11(2016), pp. 6802-6807. [10.1021/acs.nanolett.6b02494]

Laser level scheme of self-interstitials in epitaxial Ge dots encapsulated in Si

POLIMENI, Antonio;
2016

Abstract

Recently, it was shown that lasing from epitaxial Ge quantum dots (QDs) on Si substrates can be obtained if they are partially amorphized by Ge ion bombardment (GIB). Here, we present a model for the microscopic origin of the radiative transitions leading to enhanced photoluminescence (PL) from such GIB-QDs. We provide an energy level scheme for GIB-QDs in a crystalline Si matrix that is based on atomistic modeling with Monte Carlo (MC) analysis and density functional theory (DFT). The level scheme is consistent with a broad variety of PL experiments performed on as-grown and annealed GIB-QDs. Our results show that an extended point defect consisting of a split-[110] self-interstitial surrounded by a distorted crystal lattice of about 45 atoms leads to electronic states at the Γ-point of the Brillouin zone well below the conduction band minimum of crystalline Ge. Such defects in Ge QDs allow direct transitions of electrons localized at the split-interstitial with holes confined in the Ge QD. We identify the relevant growth and annealing parameters that will let GIB-QDs be employed as an efficient laser active medium
2016
Defect engineering; density functional theory; photoluminescence spectroscopy; quantum dots; Silicon photonics; Bioengineering; Chemistry (all); Materials Science (all); Condensed Matter Physics; Mechanical Engineering
01 Pubblicazione su rivista::01a Articolo in rivista
Laser level scheme of self-interstitials in epitaxial Ge dots encapsulated in Si / Grydlik, Martyna; Lusk, Mark T.; Hackl, Florian; Polimeni, Antonio; Fromherz, Thomas; Jantsch, Wolfgang; Schäffler, Friedrich; Brehm, Moritz. - In: NANO LETTERS. - ISSN 1530-6984. - 16:11(2016), pp. 6802-6807. [10.1021/acs.nanolett.6b02494]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11573/954228
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