Ultraviolet Devices and Ultraviolet Germicidal Irradiation

A special issue of Micromachines (ISSN 2072-666X). This special issue belongs to the section "A:Physics".

Deadline for manuscript submissions: closed (31 October 2024) | Viewed by 2247

Special Issue Editor


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Guest Editor
RIKEN Cluster for Pioneering Research (CPR), 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
Interests: epitaxial growth of environmentally safe semiconducting materials for solar cells (group II–IV materials, BaSi2-based heterojunction solar cells); III–V materials and nano-scale materials, i.e., silicon nanowire (Si–NWs), indium nano-particles (In NPs) and quantum dots (QDs) for efficient photovoltaic devices (solar cells) and nanotechnology application; III-nitride-based (AlGaN) (220–340 nm) band ultraviolet light-emitting diodes (UV LEDs) and UV laser diodes (UV LDs); new far-UVC class metal organic frameworks

Special Issue Information

Dear Colleagues,

In the last two decades, clean and safe wide-bandgap nitride materials have reached an outstanding stage of development, now representing the second largest semiconductor market after silicon. In particular, GaN-based blue light-emitting diodes (LEDs) are now widely used in a broad range of applications (e.g., domestic lighting, backlit smartphones, liquid crystal display screens, etc.). To further increase the application potential of nitride LEDs, use of other regions of the electromagnetic spectrum is highly desirable and current research activity is particularly focused on several topics: (1) green and red LEDs in the visible range and (2) UVA, UVB and UVC LEDs in the ultraviolet (UV) range, including far ultraviolet-C (Far-UVC) LEDs. In these cases, the improvement of LED efficiency is based on the development of innovative routes from material growth to the device fabrication process. Indeed, UV LEDs with high external quantum and wall plug efficiencies require epitaxial layers with low defect densities (dislocations, point defects, unintentional impurities, etc.); a highly radiative active region; doped layers with high carrier concentrations, low resistivities for efficient carrier injection and low power consumption; and a high light extraction efficiency (LEE). Optimizing all these parameters via epitaxial techniques involves structural, optical and electrical engineering in terms of strain management (alloying control and defect control), quantum confinement (localization effect and wavelength emission), polarization discontinuity (radiative efficiency and doping efficiency), device design (injection, extraction, and wall plug efficiency), etc.

The present Special Issue intends to highlight the results of experimental and theoretical investigations (full-length articles or reviews) on emerging UV LEDs, UV laser diodes (LDs) and UV modules including green–red LEDs. Research into both the safety and efficacy of AlGaN-based UV LEDs should continue, as well as the research into material choices and device designs. Combining these approaches, which have been pushed forward by disruptive technologies, will then lead to the emergence of high-efficiency green–red and UV LEDs, and enable the development of new applications and key technologies.

Dr. M. Ajmal Khan
Guest Editor

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Keywords

  • nitride materials
  • semiconductor devices
  • UV modules
  • AlGaN-based UV LEDs
  • 17 sustainable development goals (17-SDGs);
  • severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2);
  • virus inactivation;
  • bacteria inactivation;
  • fungus inactivation;
  • far UVC LEDs;
  • heat sink model for LED;
  • UV LED module or panel;
  • LED device simulation;
  • UV plant lightning;
  • safety standard of UV light;
  • threshold limit values (TLVs)

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Published Papers (1 paper)

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Research

10 pages, 3219 KiB  
Article
Evaluation of Phototoxicity of Short-Wavelength Laser Light Utilizing PCNA Accumulation
by Tetsuya Matsuyama, Noboru Osaka, Mikiya Yamaguchi, Naohiro Kanamaru, Kenji Wada, Ai Kawakita, Kaori Murata, Kenji Sugimoto and Koichi Okamoto
Micromachines 2024, 15(5), 646; https://doi.org/10.3390/mi15050646 - 13 May 2024
Viewed by 930
Abstract
In recent years, diseases such as age-related macular degeneration and retinal pigment degeneration caused by excessive exposure to short-wavelength visible light have become significant concerns. With the aim of quantitatively evaluating the toxicity of short-wavelength light, proliferating cell nuclear antigen (PCNA) accumulation at [...] Read more.
In recent years, diseases such as age-related macular degeneration and retinal pigment degeneration caused by excessive exposure to short-wavelength visible light have become significant concerns. With the aim of quantitatively evaluating the toxicity of short-wavelength light, proliferating cell nuclear antigen (PCNA) accumulation at the irradiation site was investigated using live cell imaging techniques to irradiate individual living cells with short-wavelength laser light. By examining the dependency of PCNA accumulation on the irradiation site within the cells and their cell cycle, it was observed that PCNA accumulation occurred only when the cell nucleus of cells in the S phase of the cell cycle was irradiated. We investigated the accumulation of PCNA at the laser irradiation site using laser light at wavelengths of 405 nm and 375 nm, with intensities ranging from 0.5 μW to 9.0 μW. The results confirmed an increase in PCNA accumulation with increasing intensity, and a higher accumulation was observed with laser light irradiation at a wavelength of 375 nm compared to 405 nm. By comparing the PCNA accumulation and 24 h cell viability, we demonstrated the feasibility of quantitatively assessing laser light toxicity through the measurement of PCNA accumulation. Full article
(This article belongs to the Special Issue Ultraviolet Devices and Ultraviolet Germicidal Irradiation)
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