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Advances in Light-Emitting Structures and Materials

A special issue of Materials (ISSN 1996-1944). This special issue belongs to the section "Optical and Photonic Materials".

Deadline for manuscript submissions: closed (30 November 2021) | Viewed by 10403

Special Issue Editors

Engineered Nanosystems Group, School of Science, Aalto University, Aalto, Finland
Interests: semiconductor/optoelectronic (nano-)devices; nanophotonics; materials/device physical models
Department of Electronics and Nanoengineering, Aalto University, Aalto, Finland
Interests: nanophotonics; optoelectronic devices; semiconductor nanowires; optics modeling

Special Issue Information

Dear Colleagues,

We invite you to contribute your original research to the Special Issue “Advances in Light-Emitting Structures and Materials” of the journal Materials. The issue summarizes recent progress in experimental and theoretical research on emission of light, including device design and fabrication, material processing, as well as the physics, modeling, characterization, tuning, and optimization of the emission properties of relevant materials and structures.

 Topics include but are not limited to:

  • Emission of light from inorganic and organic semiconductors, (nano-)structures and 2D materials;
  • Photoluminescence, electroluminescence, and optical cooling;
  • Plasmonics, gratings, photonic crystals and nanophotonics;
  • Light-emitting diodes (LEDs), lasers, novel emitter devices and on-chip optical communication;
  • Optical modeling techniques based on classical Maxwell’s equations or quantum optics;
  • Study of emission enhancement and directionality;
  • Electrical modeling, including drift–diffusion modeling, Monte Carlo simulations, and first-principle approaches;
  • Emerging/novel simulation methods based, e.g., on machine learning.

Dr. Toufik Sadi
Dr. Nicklas Anttu
Guest Editors

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. Materials 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 2600 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

  • Light-emitting materials and devices
  • Light emission characterization
  • Electrical and optical transport modeling
  • LEDs and lasers
  • Plasmonics, gratings, photonic crystals, and nanophotonics
  • Optical cooling
  • Optoelectronics, optical engineering, and photonics

Published Papers (4 papers)

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Research

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17 pages, 746 KiB  
Article
Effect of Inhomogeneous Broadening in Ultraviolet III-Nitride Light-Emitting Diodes
by Friedhard Römer, Martin Guttmann, Tim Wernicke, Michael Kneissl and Bernd Witzigmann
Materials 2021, 14(24), 7890; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14247890 - 20 Dec 2021
Cited by 10 | Viewed by 1697
Abstract
In the past years, light-emitting diodes (LED) made of GaN and its related ternary compounds with indium and aluminium have become an enabling technology in all areas of lighting. Visible LEDs have yet matured, but research on deep ultraviolet (UV) LEDs is still [...] Read more.
In the past years, light-emitting diodes (LED) made of GaN and its related ternary compounds with indium and aluminium have become an enabling technology in all areas of lighting. Visible LEDs have yet matured, but research on deep ultraviolet (UV) LEDs is still in progress. The polarisation in the anisotropic wurtzite lattice and the low free hole density in p-doped III-nitride compounds with high aluminium content make the design for high efficiency a critical step. The growth kinetics of the rather thin active quantum wells in III-nitride LEDs makes them prone to inhomogeneous broadening (IHB). Physical modelling of the active region of III-nitride LEDs supports the optimisation by revealing the opaque active region physics. In this work, we analyse the impact of the IHB on the luminescence and carrier transport III-nitride LEDs with multi-quantum well (MQW) active regions by numerical simulations comparing them to experimental results. The IHB is modelled with a statistical model that enables efficient and deterministic simulations. We analyse how the lumped electronic characteristics including the quantum efficiency and the diode ideality factor are related to the IHB and discuss how they can be used in the optimisation process. Full article
(This article belongs to the Special Issue Advances in Light-Emitting Structures and Materials)
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21 pages, 1466 KiB  
Article
Nanowire Oligomer Waveguide Modes towards Reduced Lasing Threshold
by Henrik Mäntynen, Nicklas Anttu and Harri Lipsanen
Materials 2020, 13(23), 5510; https://0-doi-org.brum.beds.ac.uk/10.3390/ma13235510 - 03 Dec 2020
Cited by 2 | Viewed by 1464
Abstract
Semiconductor nanowires offer a promising route of realizing nanolasers for the next generation of chip-scale optoelectronics and photonics applications. Established fabrication methods can produce vertical semiconductor nanowires which can themselves act both as a gain medium and as a Fabry–Pérot cavity for feedback. [...] Read more.
Semiconductor nanowires offer a promising route of realizing nanolasers for the next generation of chip-scale optoelectronics and photonics applications. Established fabrication methods can produce vertical semiconductor nanowires which can themselves act both as a gain medium and as a Fabry–Pérot cavity for feedback. The lasing threshold in such nanowire lasers is affected by the modal confinement factor and end facet reflectivities, of which the substrate end reflectivity tends to be limited due to small refractive index contrast between the nanowire and substrate. These modal properties, however, also depend strongly on the modal field profiles. In this work, we use numerical simulations to investigate waveguide modes in vertical nanowire oligomers (that is, arrangements of few vertical nanowires close to each other) and their modal properties compared to single nanowire monomers. We solve for the oligomer waveguide eigenmodes which are understood as arising from interaction of monomer modes and further compute the reflectivity of these modes at the end facets of the nanowires. We consider either the nanowires or an additional coating layer as the gain medium. We show that both types of oligomers can exhibit modes with modal properties leading to reduced lasing threshold and also give directions for further research on the topic. Full article
(This article belongs to the Special Issue Advances in Light-Emitting Structures and Materials)
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Review

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20 pages, 4604 KiB  
Review
Review of Low-Frequency Noise Properties of High-Power White LEDs during Long-Term Aging
by Vilius Palenskis, Jonas Matukas, Justinas Glemža and Sandra Pralgauskaitė
Materials 2022, 15(1), 13; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15010013 - 21 Dec 2021
Cited by 1 | Viewed by 2204
Abstract
Low-frequency noise investigation is a highly sensitive and very informative method for characterization of white nitride-based light-emitting diodes (LEDs) as well as for the evaluation of their degradation. We present a review of quality and reliability investigations of high-power (1 W and 3 [...] Read more.
Low-frequency noise investigation is a highly sensitive and very informative method for characterization of white nitride-based light-emitting diodes (LEDs) as well as for the evaluation of their degradation. We present a review of quality and reliability investigations of high-power (1 W and 3 W) white light-emitting diodes during long-term aging at the maximum permissible forward current at room temperature. The research was centered on the investigation of blue InGaN and AlInGaN quantum wells (QWs) LEDs covered by a YAG:Ce3+ phosphor layer for white light emission. The current-voltage, light output power, and low-frequency noise characteristics were measured. A broadband silicon photodetector and two-color (blue and red) selective silicon photodetectors were used for the LED output power detection, which makes it possible to separate physical processes related to the initial blue light radiation and the phosphor luminescence. Particular attention was paid to the measurement and interpretation of the simultaneous cross-correlation coefficient between electrical and optical fluctuations. The presented method enables to determine which part of fluctuations originates in the quantum well layer of the LED. The technique using the two-color selective photodetector enables investigation of changes in the noise properties of the main blue light source and the phosphor layer during the long-term aging. Full article
(This article belongs to the Special Issue Advances in Light-Emitting Structures and Materials)
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18 pages, 5510 KiB  
Review
Efficiency Models for GaN-Based Light-Emitting Diodes: Status and Challenges
by Joachim Piprek
Materials 2020, 13(22), 5174; https://0-doi-org.brum.beds.ac.uk/10.3390/ma13225174 - 17 Nov 2020
Cited by 27 | Viewed by 4439
Abstract
Light-emitting diodes (LEDs) based on Gallium Nitride (GaN) have been revolutionizing various applications in lighting, displays, biotechnology, and other fields. However, their energy efficiency is still below expectations in many cases. An unprecedented diversity of theoretical models has been developed for efficiency analysis [...] Read more.
Light-emitting diodes (LEDs) based on Gallium Nitride (GaN) have been revolutionizing various applications in lighting, displays, biotechnology, and other fields. However, their energy efficiency is still below expectations in many cases. An unprecedented diversity of theoretical models has been developed for efficiency analysis and GaN-LED design optimization, including carrier transport models, quantum well recombination models, and light extraction models. This invited review paper provides an overview of the modeling landscape and pays special attention to the influence of III-nitride material properties. It thereby identifies some key challenges and directions for future improvements. Full article
(This article belongs to the Special Issue Advances in Light-Emitting Structures and Materials)
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