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de Weerd C, Shin Y, Marino E, Kim J, Lee H, Saeed S, Gregorkiewicz T. Comparison of the Optical Properties of Graphene and Alkyl-terminated Si and Ge Quantum Dots. Sci Rep 2017; 7:14463. [PMID: 29089509 PMCID: PMC5663913 DOI: 10.1038/s41598-017-12872-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2016] [Accepted: 09/14/2017] [Indexed: 11/30/2022] Open
Abstract
Semiconductor quantum dots are widely investigated due to their size dependent energy structure. In particular, colloidal quantum dots represent a promising nanomaterial for optoelectronic devices, such as photodetectors and solar cells, but also luminescent markers for biotechnology, among other applications. Ideal materials for these applications should feature efficient radiative recombination and absorption transitions, altogether with spectral tunability over a wide range. Group IV semiconductor quantum dots can fulfill these requirements and serve as an alternative to the commonly used direct bandgap materials containing toxic and/or rare elements. Here, we present optical properties of butyl-terminated Si and Ge quantum dots and compare them to those of graphene quantum dots, finding them remarkably similar. We investigate their time-resolved photoluminescence emission as well as the photoluminescence excitation and linear absorption spectra. We contemplate that their emission characteristics indicate a (semi-) resonant activation of the emitting channel; the photoluminescence excitation shows characteristics similar to those of a molecule. The optical density is consistent with band-to-band absorption processes originating from core-related states. Hence, these observations strongly indicate a different microscopic origin for absorption and radiative recombination in the three investigated quantum dot systems.
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Affiliation(s)
- Chris de Weerd
- Institute of Physics, University of Amsterdam, Science Park 904, 1098 XH, Amsterdam, The Netherlands.
| | - Yonghun Shin
- Centre for Integrated Nanostructure Physics, Institute of Basic Science, Department of Chemistry, Sungkyunkwan University, 2066 Seoburo, Jangan-gu, Suwon, Gyeonggi-do, 16419, Republic of Korea
| | - Emanuele Marino
- Institute of Physics, University of Amsterdam, Science Park 904, 1098 XH, Amsterdam, The Netherlands
| | - Joosung Kim
- Centre for Integrated Nanostructure Physics, Institute of Basic Science, Department of Energy Science, Sungkyunkwan University, 2066 Seoburo, Jangan-gu, Suwon, Gyeonggi-do, 16419, Republic of Korea
| | - Hyoyoung Lee
- Centre for Integrated Nanostructure Physics, Institute of Basic Science, Department of Chemistry, Sungkyunkwan University, 2066 Seoburo, Jangan-gu, Suwon, Gyeonggi-do, 16419, Republic of Korea.,Centre for Integrated Nanostructure Physics, Institute of Basic Science, Department of Energy Science, Sungkyunkwan University, 2066 Seoburo, Jangan-gu, Suwon, Gyeonggi-do, 16419, Republic of Korea
| | - Saba Saeed
- Institute of Physics, University of Amsterdam, Science Park 904, 1098 XH, Amsterdam, The Netherlands.,Department of Physics, The Women University, Kutchery Campus, L.M.Q. Road, Multan, Pakistan
| | - Tom Gregorkiewicz
- Institute of Physics, University of Amsterdam, Science Park 904, 1098 XH, Amsterdam, The Netherlands.
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Grydlik M, Hackl F, Groiss H, Glaser M, Halilovic A, Fromherz T, Jantsch W, Schäffler F, Brehm M. Lasing from Glassy Ge Quantum Dots in Crystalline Si. ACS PHOTONICS 2016; 3:298-303. [PMID: 26937421 PMCID: PMC4759615 DOI: 10.1021/acsphotonics.5b00671] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Indexed: 05/25/2023]
Abstract
Semiconductor light-emitters compatible with standard Si integration technology (SIT) are of particular interest for overcoming limitations in the operating speed of microelectronic devices. Light sources based on group IV elements would be SIT-compatible, but suffer from the poor optoelectronic properties of bulk Si and Ge. Here we demonstrate that epitaxially grown Ge quantum dots (QDs) in a defect-free Si matrix show extraordinary optical properties if partially amorphized by Ge-ion bombardment (GIB). In contrast to conventional SiGe nanostructures, these QDs exhibit dramatically shortened carrier lifetimes and negligible thermal quenching of the photoluminescence (PL) up to room temperature. Microdisk resonators with embedded GIB-QDs exhibit threshold behavior as well as a superlinear increase of the integrated PL intensity with concomitant line width narrowing as the pump power increases. These findings demonstrate light amplification by stimulated emission in a fully SIT-compatible group IV nanosystem.
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Affiliation(s)
| | - Florian Hackl
- Institute of Semiconductor
and Solid State Physics, Johannes Kepler
University Linz, Altenbergerstrasse
69, A-4040 Linz, Austria
| | - Heiko Groiss
- Institute of Semiconductor
and Solid State Physics, Johannes Kepler
University Linz, Altenbergerstrasse
69, A-4040 Linz, Austria
| | - Martin Glaser
- Institute of Semiconductor
and Solid State Physics, Johannes Kepler
University Linz, Altenbergerstrasse
69, A-4040 Linz, Austria
| | - Alma Halilovic
- Institute of Semiconductor
and Solid State Physics, Johannes Kepler
University Linz, Altenbergerstrasse
69, A-4040 Linz, Austria
| | - Thomas Fromherz
- Institute of Semiconductor
and Solid State Physics, Johannes Kepler
University Linz, Altenbergerstrasse
69, A-4040 Linz, Austria
| | - Wolfgang Jantsch
- Institute of Semiconductor
and Solid State Physics, Johannes Kepler
University Linz, Altenbergerstrasse
69, A-4040 Linz, Austria
| | - Friedrich Schäffler
- Institute of Semiconductor
and Solid State Physics, Johannes Kepler
University Linz, Altenbergerstrasse
69, A-4040 Linz, Austria
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Ha NN, Giang NT, Thuy TTT, Trung NN, Dung ND, Saeed S, Gregorkiewicz T. Single phase Si1-xGex nanocrystals and the shifting of the E1 direct energy transition. NANOTECHNOLOGY 2015; 26:375701. [PMID: 26303286 DOI: 10.1088/0957-4484/26/37/375701] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We report preparation and characterization of Si1-xGex alloys with varied composition x of a large range from 0-1. The materials have been obtained by co-sputtering, followed by a heat treatment process at 600, 800, and 1000 °C for 30 min in a nitrogen gas atmosphere. X-ray diffraction data have revealed the formation of single-phase nanoparticles in the face-centered cubic (FCC) structure of Si1-xGex alloys. We found that lattice constant a of the Si1-xGex alloys increased linearly with the composition parameter x. Average diameters of the single-phase nanoparticles were estimated to be between 3-10 nm. Further evidence of FCC single-phase [Formula: see text] nanoparticles has been obtained by high resolution transmission electron microscopy. From absorption spectra, the gradual shift of the direct phononless transition identified for the E1 point in the Brillouin zone of bulk Ge is observed in single-phase Si1-xGex nanoparticles as a function of the composition parameter x.
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Affiliation(s)
- Ngo Ngoc Ha
- International Training Institute for Materials Science (ITIMS), Hanoi University of Science and Technology (HUST), No.1 Dai Co Viet, Hanoi, Vietnam
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