Submit to Nanomaterials Review for Nanomaterials Propose a Special Issue

Journal Browser

Quantum Nanostructures by Droplet Epitaxy for Optoelectronics and Quantum Information Technologies II

Special Issue Editors
Special Issue Information
Keywords
Published Papers

A special issue of Nanomaterials (ISSN 2079-4991). This special issue belongs to the section "Synthesis, Interfaces and Nanostructures".

Deadline for manuscript submissions: closed (30 August 2023) | Viewed by 7573

Share This Special Issue

Special Issue Editors

Prof. Dr. Stefano Sanguinetti

E-Mail Website
Guest Editor

Department of Materials Science, University of Milano-Bicocca, Via Roberto Cozzi, 55, 20125 Milano, Italy
Interests: III-V semiconductor heterostructures and nanostructures for optoelectronics and quantum photonic applications, including various aspects related to the growth, the optical characterization and the modeling; development of growth methods for the fabrication of III-V quantum nanostructures by droplet epitaxy thus including fundamental studies on kinetic limited growth modes and surface physics
Special Issues, Collections and Topics in MDPI journals

Dr. Stefano Vichi

E-Mail Website
Assistant Guest Editor

INFN, Section of Milano-Bicocca, Milano, Italy
Interests: quantum dots; semiconductor growth; optoelectronic devices; infrared photodetectors; III/V semiconductors; quantum simulations
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Quantum materials represent the novel frontier of physics, chemistry, and engineering, aiming to tailor the electronic and optical properties of materials via the artificial nano-synthesis of quantum nanostructures (QNs), thus controlling the electronic states at the single-atom level. QNs have been systematically explored to improve “classical” optoelectronic devices such as low-threshold and thermally stable semiconductor lasers, amplifiers, detectors, solar cells, etc. Even more relevant is their application as solid-state building blocks for emerging quantum technologies, allowing the fabrication of deterministic sources of single photons and quantum-entangled photon pairs for quantum communication, quantum simulation, and computing.

The droplet epitaxy (DE) and local droplet etching (LDE) growth protocols exploit the controlled crystallization of metal nano-droplets into compound semiconductor QNs of high crystalline and optical quality. The two epitaxy methods make it possible to obtain QNs by controlling the process kinetics with an extended chart of materials and to tailor shape and topology, thus making it possible to engineer electronic, spin, and optical properties for targeted applications.

The distance to be covered from lab achievements to device commercialization requires a huge effort that can be obtained only if the peculiarity and advantages of DE and LDE are disseminated in the semiconductor communities. For this reason, we are reiterating last year’s Special Issue on DE and LDE. The focus is again on recent advances in QN self-assembly, non-classical photon emitters (optimizing entangled photon cascade devices, tuning the emission in the telecom range, etc.), and advanced optoelectronic devices (photodetectors, quantum dot photovoltaics, etc.)

Prof. Dr. Stefano Sanguinetti
Guest Editors

Dr. Stefano Vichi
Assistant Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Nanomaterials is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2900 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

nanostructure self-assembly
quantum dots
single-photon emitters
photodetectors
photovoltaics
semiconductor lasers
quantum photonics
quantum information
semiconductor epitaxy
growth kinetics
island nucleation dynamics

Published Papers (5 papers)

Download All Papers

Research

11 pages, 612 KiB

Open AccessArticle

Strong Electric Polarizability of Cone–Shell Quantum Structures for a Large Stark Shift, Tunable Long Exciton Lifetimes, and a Dot-to-Ring Transformation

by Christian Heyn, Leonardo Ranasinghe, Kristian Deneke, Ahmed Alshaikh, Carlos A. Duque and Wolfgang Hansen

Nanomaterials 2023, 13(5), 857; https://doi.org/10.3390/nano13050857 - 25 Feb 2023

Cited by 3 | Viewed by 860

Abstract

Strain-free GaAs cone–shell quantum structures (CSQS) with widely tunable wave functions (WF) are fabricated using local droplet etching (LDE) during molecular beam epitaxy (MBE). During MBE, Al droplets are deposited on an AlGaAs surface, which then drill low-density (about 1 × 10

^{7}

[...] Read more.

^{7}

cm⁻²) nanoholes with adjustable shape and size. Subsequently, the holes are filled with GaAs to form CSQS, where the size can be adjusted by the amount of GaAs deposited for hole filling. An electric field is applied in growth direction to tune the WF in a CSQS. The resulting highly asymmetric exciton Stark shift is measured using micro-photoluminescence. Here, the unique shape of the CSQS allows a large charge–carrier separation and, thus, a strong Stark shift of up to more than 16 meV at a moderate field of 65 kV/cm. This corresponds to a very large polarizability of 8.6 × 10

^{- 6}

eVkV

^{- 2}

cm². In combination with simulations of the exciton energy, the Stark shift data allow the determination of the CSQS size and shape. Simulations of the exciton–recombination lifetime predict an elongation up to factor of 69 for the present CSQSs, tunable by the electric field. In addition, the simulations indicate the field-induced transformation of the hole WF from a disk into a quantum ring with a tunable radius from about 10 nm up to 22.5 nm. Full article

(This article belongs to the Special Issue Quantum Nanostructures by Droplet Epitaxy for Optoelectronics and Quantum Information Technologies II)

► Show Figures

Figure 1

15 pages, 3255 KiB

Open AccessArticle

MoS₂ Nanoplatelets on Hybrid Core-Shell (HyCoS) AuPd NPs for Hybrid SERS Platform for Detection of R6G

by Shusen Lin, Rutuja Mandavkar, Shalmali Burse, Md Ahasan Habib, Tasmia Khalid, Mehedi Hasan Joni, Young-Uk Chung, Sundar Kunwar and Jihoon Lee

Nanomaterials 2023, 13(4), 769; https://doi.org/10.3390/nano13040769 - 18 Feb 2023

Cited by 2 | Viewed by 1767

Abstract

In this work, a novel hybrid SERS platform incorporating hybrid core-shell (HyCoS) AuPd nanoparticles (NPs) and MoS₂ nanoplatelets has been successfully demonstrated for strong surface-enhanced Raman spectroscopy (SERS) enhancement of Rhodamine 6G (R6G). A significantly improved SERS signal of R6G is observed on the hybrid SERS platform by adapting both electromagnetic mechanism (EM) and chemical mechanism (CM) in a single platform. The EM enhancement originates from the unique plasmonic HyCoS AuPd NP template fabricated by the modified droplet epitaxy, which exhibits strong plasmon excitation of hotspots at the nanogaps of metallic NPs and abundant generation of electric fields by localized surface plasmon resonance (LSPR). Superior LSPR results from the coupling of distinctive AuPd core-shell NP and high-density background Au NPs. The CM enhancement is associated with the charge transfer from the MoS₂ nanoplatelets to the R6G. The direct contact via mixing approach with optimal mixing ratio can effectively facilitate the charges transfer to the HOMO and LUMO of R6G, leading to the orders of Raman signal amplification. The enhancement factor (EF) for the proposed hybrid platform reaches ~10¹⁰ for R6G on the hybrid SERS platform. Full article

(This article belongs to the Special Issue Quantum Nanostructures by Droplet Epitaxy for Optoelectronics and Quantum Information Technologies II)

► Show Figures

Graphical abstract

11 pages, 478 KiB

Open AccessArticle

Modeling of Masked Droplet Deposition for Site-Controlled Ga Droplets

by Stefan Feddersen, Viktoryia Zolatanosha, Ahmed Alshaikh, Dirk Reuter and Christian Heyn

Nanomaterials 2023, 13(3), 466; https://doi.org/10.3390/nano13030466 - 23 Jan 2023

Viewed by 1307

Abstract

Site-controlled Ga droplets on AlGaAs substrates are fabricated using area-selective deposition of Ga through apertures in a mask during molecular beam epitaxy (MBE). The Ga droplets can be crystallized into GaAs quantum dots using a crystallization step under As flux. In order to model the complex process, including the masked deposition of the droplets and a reduction of their number during a thermal annealing step, a multiscale kinetic Monte Carlo (mkMC) simulation of self-assembled Ga droplet formation on AlGaAs is expanded for area-selective deposition. The simulation has only two free model parameters: the activation energy for surface diffusion and the activation energy for thermal escape of adatoms from a droplet. Simulated droplet numbers within the opening of the aperture agree quantitatively with the experimental results down to the perfect site-control, with one droplet per aperture. However, the model parameters are different compared to those of the self-assembled droplet growth. We attribute this to the presence of the mask in close proximity to the surface, which modifies the local process temperature and the As background. This approach also explains the dependence of the model parameters on the size of the aperture. Full article

(This article belongs to the Special Issue Quantum Nanostructures by Droplet Epitaxy for Optoelectronics and Quantum Information Technologies II)

► Show Figures

Figure 1

15 pages, 4990 KiB

Open AccessFeature PaperArticle

Strain Relaxation of InAs Quantum Dots on Misoriented InAlAs(111) Metamorphic Substrates

by Artur Tuktamyshev, Stefano Vichi, Federico Guido Cesura, Alexey Fedorov, Giuseppe Carminati, Davide Lambardi, Jacopo Pedrini, Elisa Vitiello, Fabio Pezzoli, Sergio Bietti and Stefano Sanguinetti

Nanomaterials 2022, 12(20), 3571; https://doi.org/10.3390/nano12203571 - 12 Oct 2022

Cited by 1 | Viewed by 1450

Abstract

We investigate in detail the role of strain relaxation and capping overgrowth in the self-assembly of InAs quantum dots by droplet epitaxy. InAs quantum dots were realized on an In

_{0.6}

_{0.4}

As metamorphic buffer layer grown on a GaAs(111)A misoriented substrate. [...] Read more.

We investigate in detail the role of strain relaxation and capping overgrowth in the self-assembly of InAs quantum dots by droplet epitaxy. InAs quantum dots were realized on an In

_{0.6}

_{0.4}

As metamorphic buffer layer grown on a GaAs(111)A misoriented substrate. The comparison between the quantum electronic calculations of the optical transitions and the emission properties of the quantum dots highlights the presence of a strong quenching of the emission from larger quantum dots. Detailed analysis of the surface morphology during the capping procedure show the presence of a critical size over which the quantum dots are plastically relaxed. Full article

(This article belongs to the Special Issue Quantum Nanostructures by Droplet Epitaxy for Optoelectronics and Quantum Information Technologies II)

► Show Figures

Graphical abstract

9 pages, 428 KiB

Open AccessEditor’s ChoiceArticle

Dot-Size Dependent Excitons in Droplet-Etched Cone-Shell GaAs Quantum Dots

by Christian Heyn, Andreas Gräfenstein, Geoffrey Pirard, Leonardo Ranasinghe, Kristian Deneke, Ahmed Alshaikh, Gabriel Bester and Wolfgang Hansen

Nanomaterials 2022, 12(17), 2981; https://doi.org/10.3390/nano12172981 - 28 Aug 2022

Cited by 6 | Viewed by 1534

Abstract

Strain-free GaAs quantum dots (QDs) are fabricated by filling droplet-etched nanoholes in AlGaAs. Using a template of nominally identical nanoholes, the QD size is precisely controlled by the thickness of the GaAs filling layer. Atomic force microscopy indicates that the QDs have a cone-shell shape. From single-dot photoluminescence measurements, values of the exciton emission energy (1.58...1.82 eV), the exciton–biexciton splitting (1.8...2.5 meV), the exciton radiative lifetime of bright (0.37...0.58 ns) and dark (3.2...6.7 ns) states, the quantum efficiency (0.89...0.92), and the oscillator strength (11.2...17.1) are determined as a function of the dot size. The experimental data are interpreted by comparison with an atomistic model. Full article

(This article belongs to the Special Issue Quantum Nanostructures by Droplet Epitaxy for Optoelectronics and Quantum Information Technologies II)

► Show Figures

Figure 1

Journal Menu

Journal Browser

Quantum Nanostructures by Droplet Epitaxy for Optoelectronics and Quantum Information Technologies II

Share This Special Issue

Special Issue Editors

Special Issue Information

Keywords

Published Papers (5 papers)

Research

Further Information

Guidelines

MDPI Initiatives

Follow MDPI