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Optical Properties and Application Prospects of Novel Epitaxial Nanostructures

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A special issue of Materials (ISSN 1996-1944). This special issue belongs to the section "Advanced Nanomaterials and Nanotechnology".

Deadline for manuscript submissions: closed (30 April 2022) | Viewed by 15418

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Prof. Dr. Grzegorz Sęk

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Guest Editor

Department of Experimental Physics, Wrocław University of Science and Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland
Interests: physics and applications of novel epitaxial nanostructures; optical spectroscopy of semiconductors and nanomaterials; materials and low-dimensional structures for mid-infrared photonics; quantum electrodynamics in solid-state systems; non-classical light sources; nanophotonics

Special Issue Information

Dear Colleagues,

Epitaxial nanostructures cover a wide family of usually semiconducting nanomaterials, which have continuously developed from the mid-1980s. Their scientific importance and, in particular, their application relevance have further increased in the recent years, mainly due to tremendous progress in the development of various optoelectronic and photonic devices exploiting both a minimized size of active elements and the quantum nature of nanostructured light emitters. In this context, alongside improvements of material quality and inventions of novel compositional or morphological solutions, the exploration of the optical properties of nanostructures has become a core area of research and a necessary step in the feedback loop between epitaxial growth optimization and device performance improvement. Therefore, this Special Issue of Materials journal will be dedicated (but not limited) to the following subjects:

Development of novel epitaxial nanostructures;
Development of optical characterization methods;
Experimental determination of optical and band structure properties;
Modeling nanostructures’ electronic and optical properties;
Exploring the light–matter coupling in the nanoscale;
Nanostructures and nanomaterials as the active parts of modern devices, e.g., lasers and detectors, non-classical light sources, and photonic integrated circuits;
Novel optoelectronic and photonic applications of nanostructures.

I kindly invite all colleagues to submit regular papers, short communications or reviews addressing these exciting subjects.

Prof. Dr. Grzegorz Sęk
Guest Editor

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Keywords

epitaxial nanostructures
optical properties
optical spectroscopy
quantum dots
micro- and nanocavities
nanostructure-based optoelectronic devices
nanophotonics
non-classical light sources
photonic integrated circuits
quantum communication

Published Papers (6 papers)

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Research

15 pages, 3291 KiB

Open AccessEditor’s ChoiceArticle

Electronic and Optical Properties of InAs QDs Grown by MBE on InGaAs Metamorphic Buffer

by Paweł Wyborski, Paweł Podemski, Piotr Andrzej Wroński, Fauzia Jabeen, Sven Höfling and Grzegorz Sęk

Materials 2022, 15(3), 1071; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15031071 - 29 Jan 2022

Cited by 3 | Viewed by 2569

Abstract

We present the optical characterization of GaAs-based InAs quantum dots (QDs) grown by molecular beam epitaxy on a digitally alloyed InGaAs metamorphic buffer layer (MBL) with gradual composition ensuring a redshift of the QD emission up to the second telecom window. Based on the photoluminescence (PL) measurements and numerical calculations, we analyzed the factors influencing the energies of optical transitions in QDs, among which the QD height seems to be dominating. In addition, polarization anisotropy of the QD emission was observed, which is a fingerprint of significant valence states mixing enhanced by the QD confinement potential asymmetry, driven by the decreased strain with increasing In content in the MBL. The barrier-related transitions were probed by photoreflectance, which combined with photoluminescence data and the PL temperature dependence, allowed for the determination of the carrier activation energies and the main channels of carrier loss, identified as the carrier escape to the MBL barrier. Eventually, the zero-dimensional character of the emission was confirmed by detecting the photoluminescence from single QDs with identified features of the confined neutral exciton and biexciton complexes via the excitation power and polarization dependences. Full article

(This article belongs to the Special Issue Optical Properties and Application Prospects of Novel Epitaxial Nanostructures)

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22 pages, 3754 KiB

Open AccessArticle

Optical Quality of InAs/InP Quantum Dots on Distributed Bragg Reflector Emitting at 3rd Telecom Window Grown by Molecular Beam Epitaxy

by Tristan Smołka, Katarzyna Posmyk, Maja Wasiluk, Paweł Wyborski, Michał Gawełczyk, Paweł Mrowiński, Monika Mikulicz, Agata Zielińska, Johann Peter Reithmaier, Anna Musiał and Mohamed Benyoucef

Materials 2021, 14(21), 6270; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14216270 - 21 Oct 2021

Cited by 5 | Viewed by 2712

Abstract

We present an experimental study on the optical quality of InAs/InP quantum dots (QDs). Investigated structures have application relevance due to emission in the 3rd telecommunication window. The nanostructures are grown by ripening-assisted molecular beam epitaxy. This leads to their unique properties, i.e., low spatial density and in-plane shape symmetry. These are advantageous for non-classical light generation for quantum technologies applications. As a measure of the internal quantum efficiency, the discrepancy between calculated and experimentally determined photon extraction efficiency is used. The investigated nanostructures exhibit close to ideal emission efficiency proving their high structural quality. The thermal stability of emission is investigated by means of microphotoluminescence. This allows to determine the maximal operation temperature of the device and reveal the main emission quenching channels. Emission quenching is predominantly caused by the transition of holes and electrons to higher QD’s levels. Additionally, these carriers could further leave the confinement potential via the dense ladder of QD states. Single QD emission is observed up to temperatures of about 100 K, comparable to the best results obtained for epitaxial QDs in this spectral range. The fundamental limit for the emission rate is the excitation radiative lifetime, which spreads from below 0.5 to almost 1.9 ns (GHz operation) without any clear spectral dispersion. Furthermore, carrier dynamics is also determined using time-correlated single-photon counting. Full article

(This article belongs to the Special Issue Optical Properties and Application Prospects of Novel Epitaxial Nanostructures)

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9 pages, 3116 KiB

Open AccessArticle

Metamorphic Buffer Layer Platform for 1550 nm Single-Photon Sources Grown by MBE on (100) GaAs Substrate

by Piotr Andrzej Wroński, Paweł Wyborski, Anna Musiał, Paweł Podemski, Grzegorz Sęk, Sven Höfling and Fauzia Jabeen

Materials 2021, 14(18), 5221; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14185221 - 10 Sep 2021

Cited by 8 | Viewed by 2111

Abstract

We demonstrate single-photon emission with a low probability of multiphoton events of 5% in the C-band of telecommunication spectral range of standard silica fibers from molecular beam epitaxy grown (100)-GaAs-based structure with InAs quantum dots (QDs) on a metamorphic buffer layer. For this purpose, we propose and implement graded In content digitally alloyed InGaAs metamorphic buffer layer with maximal In content of 42% and GaAs/AlAs distributed Bragg reflector underneath to enhance the extraction efficiency of QD emission. The fundamental limit of the emission rate for the investigated structures is 0.5 GHz based on an emission lifetime of 1.95 ns determined from time-resolved photoluminescence. We prove the relevance of a proposed technology platform for the realization of non-classical light sources in the context of fiber-based quantum communication applications. Full article

(This article belongs to the Special Issue Optical Properties and Application Prospects of Novel Epitaxial Nanostructures)

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Graphical abstract

15 pages, 4758 KiB

Open AccessArticle

Magneto-Optical Characterization of Trions in Symmetric InP-Based Quantum Dots for Quantum Communication Applications

by Wojciech Rudno-Rudziński, Marek Burakowski, Johann P. Reithmaier, Anna Musiał and Mohamed Benyoucef

Materials 2021, 14(4), 942; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14040942 - 17 Feb 2021

Cited by 10 | Viewed by 2114

Abstract

Magneto-optical parameters of trions in novel large and symmetric InP-based quantum dots, uncommon for molecular beam epitaxy-grown nanostructures, with emission in the third telecom window, are measured in Voigt and Faraday configurations of an external magnetic field. The diamagnetic coefficients are found to be in the range of 1.5–4 μeV/T², and 8–15 μeV/T², respectively out-of-plane and in-plane of the dots. The determined values of diamagnetic shifts are related to the anisotropy of dot sizes. Trion g-factors are measured to be relatively small, in the range of 0.3–0.7 and 0.5–1.3, in both configurations, respectively. Analysis of single carrier g-factors, based on the formalism of spin-correlated orbital currents, leads to similar values for hole and electron of ~0.25 for Voigt and g_e ≈ −5; g_h ≈ +6 for Faraday configuration of the magnetic field. Values of g-factors close to zero measured in Voigt configuration make the investigated dots promising for electrical tuning of the g-factor sign, required for schemes of single spin control in qubit applications. Full article

(This article belongs to the Special Issue Optical Properties and Application Prospects of Novel Epitaxial Nanostructures)

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12 pages, 2577 KiB

Open AccessArticle

InP-Substrate-Based Quantum Dashes on a DBR as Single-Photon Emitters at the Third Telecommunication Window

by Paweł Wyborski, Anna Musiał, Paweł Mrowiński, Paweł Podemski, Vasilij Baumann, Piotr Wroński, Fauzia Jabeen, Sven Höfling and Grzegorz Sęk

Materials 2021, 14(4), 759; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14040759 - 05 Feb 2021

Cited by 5 | Viewed by 2520

Abstract

We investigated emission properties of photonic structures with InAs/InGaAlAs/InP quantum dashes grown by molecular beam epitaxy on a distributed Bragg reflector. In high-spatial-resolution photoluminescence experiment, well-resolved sharp spectral lines are observed and single-photon emission is detected in the third telecommunication window characterized by very low multiphoton events probabilities. The photoluminescence spectra measured on simple photonic structures in the form of cylindrical mesas reveal significant intensity enhancement by a factor of 4 when compared to a planar sample. These results are supported by simulations of the electromagnetic field distribution, which show emission extraction efficiencies even above 18% for optimized designs. When combined with relatively simple and undemanding fabrication approach, it makes this kind of structures competitive with the existing solutions in that spectral range and prospective in the context of efficient and practical single-photon sources for fiber-based quantum networks applications. Full article

(This article belongs to the Special Issue Optical Properties and Application Prospects of Novel Epitaxial Nanostructures)

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17 pages, 948 KiB

Open AccessArticle

Optical Properties of Site-Selectively Grown InAs/InP Quantum Dots with Predefined Positioning by Block Copolymer Lithography

by Paweł Holewa, Jakub Jasiński, Artem Shikin, Elizaveta Lebedkina, Aleksander Maryński, Marcin Syperek and Elizaveta Semenova

Materials 2021, 14(2), 391; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14020391 - 14 Jan 2021

Cited by 3 | Viewed by 2203

Abstract

The InAs/InP quantum dots (QDs) are investigated by time-integrated (PL) and time-resolved photoluminescence (TRPL) experiments. The QDs are fabricated site-selectively by droplet epitaxy technique using block copolymer lithography. The estimated QDs surface density is ∼1.5 × 10¹⁰ cm⁻². The PL [...] Read more.

T = 300 K

is centered at 1.5 μm. Below

T = 250 K

, the PL spectrum shows a fine structure consisting of emission modes attributed to the multimodal QDs size distribution. Temperature-dependent PL reveals negligible carrier transfer among QDs, suggesting good carrier confinement confirmed by theoretical calculations and the TRPL experiment. The PL intensity quench and related energies imply the presence of carrier losses among InP barrier states before carrier capture by QD states. The TRPL experiment highlighted the role of the carrier reservoir in InP. The elongation of PL rise time with temperature imply inefficient carrier capture from the reservoir to QDs. The TRPL experiment at

T = 15 K

reveals the existence of two PL decay components with strong dispersion across the emission spectrum. The decay times dispersion is attributed to different electron-hole confinement regimes for the studied QDs within their broad distribution affected by the size and chemical content inhomogeneities. Full article

(This article belongs to the Special Issue Optical Properties and Application Prospects of Novel Epitaxial Nanostructures)

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