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Ge/Al and Ge/Si3N4/Al Core/Shell Quantum Dot Lattices in Alumina: Boosting the Spectral Response by Tensile Strain

Periša, Ivana; Tkalčević, Marija; Isaković, Senad; Basioli, Lovro; Ivanda, Mile; Bernstorff, Siegrid; Mičetić, Maja (2022) Ge/Al and Ge/Si3N4/Al Core/Shell Quantum Dot Lattices in Alumina: Boosting the Spectral Response by Tensile Strain. Materials . ISSN 1996-1944

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We investigated the production conditions and optoelectrical properties of thin film material consisting of regularly ordered core/shell Ge/Al and Ge/Si3N4/Al quantum dots (QDs) in an alumina matrix. The materials were produced by self– assembled growth achieved by means of multilayer magnetron sputtering deposition. We demonstrated the successful fabrication of well-ordered 3D lattices of Ge/Al and Ge/Si3N4/Al core/shell quantum dots with a body-centred tetragonal arrangement within the Al2O3 matrix. The addition of shells to the Ge core enables a strong tuning of the optical and electrical properties of the material. An Al shell induces a bandgap shift toward smaller energies, and, in addition, it prevents Ge oxidation. The addition of a thin Si3N4 shell induces huge changes in the material spectral response, i.e., in the number of extracted excitons produced by a single photon. It increases both the absolute value and the width of the spectral response. For the best sample, we achieved an enhancement of over 250% of the produced number of excitons in the measured energy range. The observed changes are, as it seems, the consequence of the large tensile strain in Ge QDs which is induced by the Si3N4 shell addition and which is measured to be about 3% for the most strained QDs. The tensile strain causes activation of the direct bandgap of germanium, which has a very strong effect on the spectral response of the material.

Item Type: Article
Uncontrolled Keywords: core/shell QDs; germanium QDs; tensile strain; GISAXS; thin films
Subjects: NATURAL SCIENCES > Physics
TECHNICAL SCIENCES > Chemical Engineering
TECHNICAL SCIENCES > Chemical Engineering > Chemical Engineering in Material Development
TECHNICAL SCIENCES > Interdisciplinary Technical Sciences > Micro and Nano Technologies
Divisions: Division of Materials Physics
Project titleProject leaderProject codeProject type
3D mreže kompleksnih Ge-baziranih nanostruktura u staklima: svojstva i primjene-NetNanoMaja MičetićIP-2018-01-3633HRZZ
Depositing User: Marija Tkalčević
Date Deposited: 06 Dec 2022 12:46

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