Structural and Optoelectronic Properties of Self-Assembled Semiconductor Nanostructures

A special issue of Nanomaterials (ISSN 2079-4991). This special issue belongs to the section "Nanoelectronics, Nanosensors and Devices".

Deadline for manuscript submissions: closed (30 September 2021) | Viewed by 11731

Special Issue Editor


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Guest Editor
Center for Hybrid Nanostructures (CHyN), University of Hamburg, Hamburg, Germany
Interests: Molecular beam epitaxy (MBE) of semiconductor nanostructures; Structural characterization with atomic force microscopy (AFM) and x-ray diffration (XRD); Modeling of epitaxial self-assembly mechanisms; Optical characterization with photoluminescence (PL) spectroscopy; Modeling of optical properties; Applications for self-assembled nanoholes that are formed by local droplet etching during semiconductor epitaxy

Special Issue Information

Dear Colleagues,

The self-assembled ordering of matter is a fascinating physical phenomenon and opens powerful opportunities for the creation of nanometer-sized structures. Semiconductor nanostructures substantially benefit from a size reduction down to the wavelength of de Broglie matter-waves where quantum effects become significant. This Special Issue focusses on epitaxial nanostructures where ensembles are generated on planar substrates. One crucial aspect is the control of the quantized energy states and optoelectronic properties by tuning the size, shape, and composition of the nanostructures. This requires advanced fabrication techniques like molecular beam epitaxy, where self-assembly is obtained, for example, by utilizing the strain-energy between epitaxial layers or by using droplet-epitaxy-based techniques. Advanced spectroscopy enlightens the optoelectronic features of the realized structures, like quantum dots, disks, and rings as well as coupled quantum systems, and theory provides support for an understanding of the spectroscopic findings, optimization strategies, and development of device concepts.

Dr. Christian Heyn
Guest Editor

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Keywords

  • semiconductor nanostructures
  • self-assembly
  • Stranski–Krastanov growth
  • Volmer–Weber growth
  • quantum dots
  • quantum rings
  • hybrid quantum systems
  • spectroscopy
  • photoluminescence
  • theory

Published Papers (4 papers)

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Research

23 pages, 5505 KiB  
Article
Self-Consistent Schrödinger-Poisson Study of Electronic Properties of GaAs Quantum Well Wires with Various Cross-Sectional Shapes
by John A. Gil-Corrales, Juan A. Vinasco, Adrian Radu, Ricardo L. Restrepo, Alvaro L. Morales, Miguel E. Mora-Ramos and Carlos A. Duque
Nanomaterials 2021, 11(5), 1219; https://doi.org/10.3390/nano11051219 - 05 May 2021
Cited by 9 | Viewed by 3116
Abstract
Quantum wires continue to be a subject of novel applications in the fields of electronics and optoelectronics. In this work, we revisit the problem of determining the electron states in semiconductor quantum wires in a self-consistent way. For that purpose, we numerically solve [...] Read more.
Quantum wires continue to be a subject of novel applications in the fields of electronics and optoelectronics. In this work, we revisit the problem of determining the electron states in semiconductor quantum wires in a self-consistent way. For that purpose, we numerically solve the 2D system of coupled Schrödinger and Poisson equations within the envelope function and effective mass approximations. The calculation method uses the finite-element approach. Circle, square, triangle and pentagon geometries are considered for the wire cross-sectional shape. The features of self-consistent band profiles and confined electron state spectra are discussed, in the latter case, as functions of the transverse wire size and temperature. Particular attention is paid to elucidate the origin of Friedel-like oscillations in the density of carriers at low temperatures. Full article
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10 pages, 2213 KiB  
Article
Wafer-Scale Epitaxial Low Density InAs/GaAs Quantum Dot for Single Photon Emitter in Three-Inch Substrate
by Xiaoying Huang, Rongbin Su, Jiawei Yang, Mujie Rao, Jin Liu, Ying Yu and Siyuan Yu
Nanomaterials 2021, 11(4), 930; https://doi.org/10.3390/nano11040930 - 06 Apr 2021
Cited by 9 | Viewed by 2891
Abstract
In this work, we successfully achieved wafer-scale low density InAs/GaAs quantum dots (QDs) for single photon emitter on three-inch wafer by precisely controlling the growth parameters. The highly uniform InAs/GaAs QDs show low density of μ0.96/μm2 within the [...] Read more.
In this work, we successfully achieved wafer-scale low density InAs/GaAs quantum dots (QDs) for single photon emitter on three-inch wafer by precisely controlling the growth parameters. The highly uniform InAs/GaAs QDs show low density of μ0.96/μm2 within the radius of 2 cm. When embedding into a circular Bragg grating cavity on highly efficient broadband reflector (CBR-HBR), the single QDs show excellent optoelectronic properties with the linewidth of 3± 0.08 GHz, the second-order correlation factor g2(τ)=0.0322 ±0.0023, and an exciton life time of 323 ps under two-photon resonant excitation. Full article
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10 pages, 7188 KiB  
Article
Solid-State Dewetting Dynamics of Amorphous Ge Thin Films on Silicon Dioxide Substrates
by Dimosthenis Toliopoulos, Alexey Fedorov, Sergio Bietti, Monica Bollani, Emiliano Bonera, Andrea Ballabio, Giovanni Isella, Mohammed Bouabdellaoui, Marco Abbarchi, Shiro Tsukamoto and Stefano Sanguinetti
Nanomaterials 2020, 10(12), 2542; https://doi.org/10.3390/nano10122542 - 17 Dec 2020
Cited by 7 | Viewed by 2180
Abstract
We report on the dewetting process, in a high vacuum environment, of amorphous Ge thin films on SiO2/Si (001). A detailed insight of the dewetting is obtained by in situ reflection high-energy electron diffraction and ex situ scanning electron microscopy. These [...] Read more.
We report on the dewetting process, in a high vacuum environment, of amorphous Ge thin films on SiO2/Si (001). A detailed insight of the dewetting is obtained by in situ reflection high-energy electron diffraction and ex situ scanning electron microscopy. These characterizations show that the amorphous Ge films dewet into Ge crystalline nano-islands with dynamics dominated by crystallization of the amorphous material into crystalline nano-seeds and material transport at Ge islands. Surface energy minimization determines the dewetting process of crystalline Ge and controls the final stages of the process. At very high temperatures, coarsening of the island size distribution is observed. Full article
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12 pages, 8052 KiB  
Article
Combining Spin-Seebeck and Nernst Effects in Aligned MnBi/Bi Composites
by Brandi L. Wooten, Koen Vandaele, Stephen R. Boona and Joseph P. Heremans
Nanomaterials 2020, 10(10), 2083; https://doi.org/10.3390/nano10102083 - 21 Oct 2020
Cited by 5 | Viewed by 2864
Abstract
The spin-Seebeck effect (SSE) is an advective transport process traditionally studied in bilayers composed of a ferromagnet (FM) and a non-magnetic metal (NM) with strong spin-orbit coupling. In a temperature gradient, the flux of magnons in the FM transfers spin-angular momentum to electrons [...] Read more.
The spin-Seebeck effect (SSE) is an advective transport process traditionally studied in bilayers composed of a ferromagnet (FM) and a non-magnetic metal (NM) with strong spin-orbit coupling. In a temperature gradient, the flux of magnons in the FM transfers spin-angular momentum to electrons in the NM, which by the inverse spin-Hall effect generates an SSE voltage. In contrast, the Nernst effect is a bulk transport phenomenon in homogeneous NMs or FMs. These effects share the same geometry, and we show here that they can be added to each other in a new combination of FM/NM composites where synthesis via in-field annealing results in the FM material (MnBi) forming aligned needles inside an NM matrix with strong spin-orbit coupling (SOC) (Bi). Through examination of the materials’ microstructural, magnetic, and transport properties, we searched for signs of enhanced transverse thermopower facilitated by an SSE contribution from MnBi adding to the Nernst effect in Bi. Our results indicate that these two signals are additive in samples with lower MnBi concentrations, suggesting a new way forward in the study of SSE composite materials. Full article
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