ABSTRACT
This paper reports an improved deep ultraviolet LED (DUV-LED) packaging based on Si Micro-Electro-Mechanical Systems (MEMS) process technology. The Si package (Si-PKG) consists of a cavity formed by Si crystalline anisotropic wet etching and through-silicon vias (TSVs) filled with electroplated Cu. The Si-PKG is hermetically sealed by laser local heating of screen-printed glass frit. This technology allows for the use of a DUV-transparent glass substrate, which has an unmatched coefficient of thermal expansion (CTE). Using a high-density array of TSV capped with AuSn solder bumps, the cooling performance of the DUV-LED has been greatly improved. And the contribution by the Si (111) side reflection of Si-PKG to the total light output was confirmed 13 %. As a result, an optical output of 114 % (50 mW) and a volumetric light power density of 380 % (14 mW/mm3) were recorded compared with the conventional AlN-packaged device. The developed compact low-cost Si-PKG is promising for wider applications of the DUV-LED including the disinfection of the new coronaviruses. © 2022 Elsevier B.V.
ABSTRACT
A novel Multi-Quantum-Well Deep Ultra Violet Light Emitting Diode (DUV-LED) device with a near-pole hole insertion layer and far-pole hole insertion layer was proposed and carefully studied. It was found that remarkable enhancements both in the light output power (LOP) and the internal quantum efficiency (IQE) could be realized by using the far-electrode hole insertion layer and near-electrode hole insertion layer compared to the conventional DUV-LED device. Inserting the near-polar hole insertion layer can increase the electric field in the hole injection layer, which will promote the ionization of the acceptor, increase the hole concentration, and enhance the light-emitting performance of the device. In addition, inserting the far-pole hole insertion layer can suppress electron leakage and promote the hole injection. At the same time, the updated electron barrier height of P-AlGaN/GaN will indirectly weaken the electrostatic field in the hole injection layer, which remains inconducive to the ionization of the acceptor, implying that the electrostatic field between the P-AGaN/GaN layer can optimize the efficiency droop of the device.
ABSTRACT
Although, Low-pressure (LP) mercury lamps that emit wavelengths of around 254 nm have been widely applied as ultraviolet (UV) light devices for decontamination of microorganisms, they have raised environmental concerns due to their mercury content. Therefore, UV-LED lamps have high potential for practical use as a replacement for LP mercury lamps. In this study, we evaluated the efficacy of 265-nm UV irradiation in comparison to 254-nm and 280-nm UV irradiation for inactivating infectious severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Irradiation from a 265-nm deep UV light-emitting diode (DUV-LED) lamp efficiently inactivated SARS-CoV-2 at a similar level as a 254-nm UV cold cathode lamp, and at a higher level than a 280-nm DUV-LED lamp.
ABSTRACT
The world is combating the emergence of Coronavirus disease 2019 (COVID-19) caused by novel coronavirus; severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Further, due to the presence of SARS-CoV-2 in sewage and stool samples, its transmission through water routes cannot be neglected. Thus, the efficient treatment of wastewater is a matter of utmost importance. The conventional wastewater treatment processes demonstrate a wide variability in absolute removal of viruses from wastewater, thereby posing a severe threat to human health and environment. The fate of SARS-CoV-2 in the wastewater treatment plants and its removal during various treatment stages remains unexplored and demands immediate attention; particularly, where treated effluent is utilised as reclaimed water. Consequently, understanding the prevalence of pathogenic viruses in untreated/treated waters and their removal techniques has become the topical issue of the scientific community. The key objective of the present study is to provide an insight into the distribution of viruses in wastewater, as well as the prevalence of SARS-CoV-2, and its possible transmission by the faecal-oral route. The review also gives a detailed account of the major waterborne and non-waterborne viruses, and environmental factors governing the survival of viruses. Furthermore, a comprehensive description of the potential methods (physical, chemical, and biological) for removal of viruses from wastewater has been presented. The present study also intends to analyse the research trends in microalgae-mediated virus removal and, inactivation. The review also addresses the UN SDG 'Clean Water and Sanitation' as it is aimed at providing pathogenically safe water for recycling purposes.