Bandgap atomistic calculations on hydrogen-passivated GeSi nanocrystals

Abstract We present a detailed study regarding the bandgap dependence on diameter and composition of spherical Ge-rich Ge x Si1−x nanocrystals (NCs). For this, we conducted a series of atomistic density functional theory (DFT) calculations on H-passivated NCs of Ge-rich GeSi random alloys, with Ge a...

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Autores principales:	Ovidiu Cojocaru, Ana-Maria Lepadatu, George Alexandru Nemnes, Toma Stoica, Magdalena Lidia Ciurea
Formato:	article
Lenguaje:	EN
Publicado:	Nature Portfolio 2021
Materias:	Medicine R Science Q
Acceso en línea:	https://doaj.org/article/c3f5e3877bb3438fa7f5827470cbc551
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spelling	oai:doaj.org-article:c3f5e3877bb3438fa7f5827470cbc5512021-12-02T16:10:36ZBandgap atomistic calculations on hydrogen-passivated GeSi nanocrystals10.1038/s41598-021-92936-z2045-2322https://doaj.org/article/c3f5e3877bb3438fa7f5827470cbc5512021-06-01T00:00:00Zhttps://doi.org/10.1038/s41598-021-92936-zhttps://doaj.org/toc/2045-2322Abstract We present a detailed study regarding the bandgap dependence on diameter and composition of spherical Ge-rich Ge x Si1−x nanocrystals (NCs). For this, we conducted a series of atomistic density functional theory (DFT) calculations on H-passivated NCs of Ge-rich GeSi random alloys, with Ge atomic concentration varied from 50 to 100% and diameters ranging from 1 to 4 nm. As a result of the dominant confinement effect in the DFT computations, a composition invariance of the line shape of the bandgap diameter dependence was found for the entire computation range, the curves being shifted for different Ge concentrations by ΔE(eV) = 0.651(1 − x). The shape of the dependence of NCs bandgap on the diameter is well described by a power function 4.58/d 1.25 for 2–4 nm diameter range, while for smaller diameters, there is a tendency to limit the bandgap to a finite value. By H-passivation of the NC surface, the effect of surface states near the band edges is excluded aiming to accurately determine the NC bandgap. The number of H atoms necessary to fully passivate the spherical Ge x Si1−x NC surface reaches the total number atoms of the Ge + Si core for smallest NCs and still remains about 25% from total number of atoms for bigger NC diameters of 4 nm. The findings are in line with existing theoretical and experimental published data on pure Ge NCs and allow the evaluation of the GeSi NCs behavior required by desired optical sensor applications for which there is a lack of DFT simulation data in literature.Ovidiu CojocaruAna-Maria LepadatuGeorge Alexandru NemnesToma StoicaMagdalena Lidia CiureaNature PortfolioarticleMedicineRScienceQENScientific Reports, Vol 11, Iss 1, Pp 1-10 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R Science Q
spellingShingle	Medicine R Science Q Ovidiu Cojocaru Ana-Maria Lepadatu George Alexandru Nemnes Toma Stoica Magdalena Lidia Ciurea Bandgap atomistic calculations on hydrogen-passivated GeSi nanocrystals
description	Abstract We present a detailed study regarding the bandgap dependence on diameter and composition of spherical Ge-rich Ge x Si1−x nanocrystals (NCs). For this, we conducted a series of atomistic density functional theory (DFT) calculations on H-passivated NCs of Ge-rich GeSi random alloys, with Ge atomic concentration varied from 50 to 100% and diameters ranging from 1 to 4 nm. As a result of the dominant confinement effect in the DFT computations, a composition invariance of the line shape of the bandgap diameter dependence was found for the entire computation range, the curves being shifted for different Ge concentrations by ΔE(eV) = 0.651(1 − x). The shape of the dependence of NCs bandgap on the diameter is well described by a power function 4.58/d 1.25 for 2–4 nm diameter range, while for smaller diameters, there is a tendency to limit the bandgap to a finite value. By H-passivation of the NC surface, the effect of surface states near the band edges is excluded aiming to accurately determine the NC bandgap. The number of H atoms necessary to fully passivate the spherical Ge x Si1−x NC surface reaches the total number atoms of the Ge + Si core for smallest NCs and still remains about 25% from total number of atoms for bigger NC diameters of 4 nm. The findings are in line with existing theoretical and experimental published data on pure Ge NCs and allow the evaluation of the GeSi NCs behavior required by desired optical sensor applications for which there is a lack of DFT simulation data in literature.
format	article
author	Ovidiu Cojocaru Ana-Maria Lepadatu George Alexandru Nemnes Toma Stoica Magdalena Lidia Ciurea
author_facet	Ovidiu Cojocaru Ana-Maria Lepadatu George Alexandru Nemnes Toma Stoica Magdalena Lidia Ciurea
author_sort	Ovidiu Cojocaru
title	Bandgap atomistic calculations on hydrogen-passivated GeSi nanocrystals
title_short	Bandgap atomistic calculations on hydrogen-passivated GeSi nanocrystals
title_full	Bandgap atomistic calculations on hydrogen-passivated GeSi nanocrystals
title_fullStr	Bandgap atomistic calculations on hydrogen-passivated GeSi nanocrystals
title_full_unstemmed	Bandgap atomistic calculations on hydrogen-passivated GeSi nanocrystals
title_sort	bandgap atomistic calculations on hydrogen-passivated gesi nanocrystals
publisher	Nature Portfolio
publishDate	2021
url	https://doaj.org/article/c3f5e3877bb3438fa7f5827470cbc551
work_keys_str_mv	AT ovidiucojocaru bandgapatomisticcalculationsonhydrogenpassivatedgesinanocrystals AT anamarialepadatu bandgapatomisticcalculationsonhydrogenpassivatedgesinanocrystals AT georgealexandrunemnes bandgapatomisticcalculationsonhydrogenpassivatedgesinanocrystals AT tomastoica bandgapatomisticcalculationsonhydrogenpassivatedgesinanocrystals AT magdalenalidiaciurea bandgapatomisticcalculationsonhydrogenpassivatedgesinanocrystals
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Bandgap atomistic calculations on hydrogen-passivated GeSi nanocrystals

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