UV-C LEDs for Sterilization Applications

2014 ◽  
Vol 2014 (DPC) ◽  
pp. 002132-002166
Author(s):  
Joe Grzyb
Keyword(s):  
High Voltage ◽  
High Efficiency ◽  
Lattice Mismatch ◽  
Uv Light ◽  
High Reliability ◽  
Ultra Violet ◽  
Device Fabrication ◽  
Light Sources ◽  
Wafer Processing ◽  
Uv C

HexaTech has developed a proprietary, patented process for manufacturing bulk aluminum nitride (AlN) crystals and semiconductor wafers. HexaTech is leveraging this unique capability to develop and commercialize high-performance, long-lifetime Ultra Violet Light Emitting Diodes (UV-C LEDs) for disinfection applications (particularly clean water) and high-voltage, high-efficiency power semiconductors for power conversion applications (particularly smart grid). Deep-ultraviolet light with wavelength in the range of 250 to 280nm (UV-C) has been used to sterilize liquids, air and surfaces for over a century. UV-C light is absorbed by and damages the DNA of harmful bacteria, either outright killing the bacteria or preventing their ability to replicate. Traditionally, high voltage mercury tubes have been used to generate such UV light. While mercury tubes have enabled UV-C use bulk disinfection applications such as drinking water and waste water, they have proven impractical in point-of-use applications where small size, elimination of harmful mercury, and high reliability under intermittent use conditions are required. The solution is to generate UV-C light using LEDs. In spite of numerous efforts, the power output and reliability of UV-C LEDs is still not sufficient for their adoption as practical and reliable UV-C light sources. Traditionally, AlGaN-based UV-C LEDs have been fabricated on sapphire substrates. Because of huge number of defects caused by the lattice mismatch between the AlGaN active layers and the sapphire substrate, these sapphire-based UV-C LEDs show performance and reliability of limited interest to sterilization system manufacturers. HexaTech's AlN crystal growth and wafer processing technology results in single crystal wafers with extremely high quality. HexaTech and its development partners have fabricated UV-C LEDs that have shown performance dramatically superior to other devices in the market in terms of output power, power density and lifetime. In this presentation, we will discuss the market requirements for UV-C LEDs, the challenges of UV-C device fabrication, package and test, and the solutions that are being pursued.

Photo-Electron Emission Microscopy of Semiconductor Surfaces

1998 ◽  
Vol 4 (S2) ◽  
pp. 606-607
Author(s):  
R.J. Nemanich ◽  
S.L. English ◽  
J.D. Hartman ◽  
W. Yang ◽  
H. Ade ◽  
...  
Keyword(s):  
Electron Emission ◽  
Imaging System ◽  
Uv Light ◽  
Ultra Violet ◽  
Objective Lens ◽  
Electron Optics ◽  
Light Sources ◽  
Emission Microscopy ◽  
Electron Imaging ◽  
Crucial Part

The technique of photo-electron emission microscopy (PEEM) is based on imaging of photo excited electrons from a surface. Typically ultra violet (UV) light above the work function of a metal will cause electrons to be emitted from a surface. Since photo excited electrons originate very near to the surface, they essentially reflect the electronic structure of the surface. These electrons may be accelerated and imaged, and the image will reflect the properties of the surface.While the PEEM technique has been understood in a basic sense for many years, it has been limited by the lack of high intensity UV light sources. The most crucial part of the electron imaging system for PEEM, the objective lens, is essentially the same as for the sister technique of low energy electron microscopy (LEEM), and advances in electron optics capabilities have been exploited both for LEEM and for PEEM.

scholarly journals Effect of UV-Light Treatment on Efficiency of Perovskite Solar Cells (PSCs)

Energies ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1069 ◽  
Author(s):  
Sangmo Kim ◽  
Hoang Van Quy ◽  
Hyung Wook Choi ◽  
Chung Wung Bark
Keyword(s):  
Solar Cells ◽  
Conversion Efficiency ◽  
Uv Light ◽  
Perovskite Solar Cells ◽  
Ultra Violet ◽  
Light Treatment ◽  
Light Sources ◽  
Perovskite Layer ◽  
Solar Conversion ◽  
Solar Conversion Efficiency

We employed ultra-violet (UV) light treatment on the TiO2 layer prior to coating the perovskite layer to improve the solar conversion efficiency of perovskite solar cells (PSCs). A laboratory-made UV treatment system was equipped with various UV light sources (8 W power; maximum wavelengths of 254, 302, and 365 nm). The UV light treatment improved the power conversion efficiency (PCE) while coating the uniformity layer and removing impurities from the surface of cells. After the PSCs were exposed to UV light, their PCE developed approximately 10% efficiency; PBI2 decreased without changing the structure.

scholarly journals ALTERNATIVE UV LIGHT SOURCES FOR SURFACE DISINFECTION

2021 ◽  
Vol 1 ◽  
pp. 218-222
Author(s):  
Atis Skudra ◽  
Linda Mezule ◽  
Karina Spunde ◽  
Gita Revalde ◽  
Anna Zajakina ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Contact Time ◽  
Uv Light ◽  
Microbial Inactivation ◽  
Light Sources ◽  
The Novel ◽  
Surface Disinfection ◽  
E Coli ◽  
Uv C ◽  
Harmful Effects

Mercury UV-C light sources are long known to be efficient for microbial inactivation and have been widely used. At the same time, the radiation, if used in inappropriate doses and spectral regimes, can also cause harmful effects to human tissue. The aim of the study was to evaluate the applicability of the novel UV light sources from thallium – antimony at different UV-C. For the research specially made light sources were produced. The influence of UV-C radiation in the range of 200 - 280 nm was tested on Gramnegative bacterium Escherichia coli, both with mercury and thallium. More than 99.99 % inactivation of E. coli cells was obtained after 10 min contact time for thallium – antimony UV-C light source, demonstrating the potential of the produced lamps.

Highly Integrated and Isolated Universal Half-Bridge Power Gate Driver and Associated Flyback Power Supply for High Temperature and High Reliability Applications

2014 ◽  
Vol 2014 (HITEC) ◽  
pp. 000206-000213
Author(s):  
David Gras ◽  
Christophe Pautrel ◽  
Amir Fanaei ◽  
Gregory Thepaut ◽  
Maxime Chabert ◽  
...  
Keyword(s):  
High Temperature ◽  
High Voltage ◽  
Power Supply ◽  
High Efficiency ◽  
High Reliability ◽  
System Level ◽  
Switching Frequency ◽  
Solder Paste ◽  
High Side ◽  
Gate Driver

In this paper we present a highly integrated, high-temperature isolated, half-bridge power gate driver demo board, based on turnkey X-REL chipset: XTR26010 (High-Temperature Intelligent Gate Driver), XTR40010 (High-Temperature Isolated Two Channel Transceiver), XTR30010 (High-Temperature PWM Controller), and XTR2N0825 (High-Temperature 80V N-Channel Power MOSFET). The XTR26010 is the key circuit in this chipset for power gate drive application. The XTR26010 circuit has been designed with a high focus in offering a robust, reliable and efficient solution for driving a large variety of high-temperature, high-voltage, and high-efficiency power transistors (SiC, GaN, Si) existing in the market. Furthermore, the XTR26010 circuit implements an unprecedented functionality for high-temperature drivers allowing safe operation at system level by preventing any cross-conduction between high-side and low-side switches, through isolated communication between high-side and low-side drivers. The XTR40010 is used for isolated data communication between a microcontroller or a PWM controller with the power driver (XTR26010). For supplying the half-bridge gate driver, a compact isolated flyback power supply has been developed thanks to the versatile voltage mode PWM controller XTR30010 and the XT2N0825 N-Channel MOSFET. The full system has been successfully tested while driving different brands of SiC MOSFETs up to Ta=200°C, 600kHz of switching frequency and 600V high-voltage bus (limited by isolation transformers used). The demo board presented can be easily modified to drive other SiC and GaN transistors available in the market. The 200°C limitation of the demo board is due to passives, PCB material, and the solder paste used. However, all X-REL active circuits have been qualified within specifications well above 230°C.

Navigation of Lutzomyia longipalpis (Diptera: Psychodidae) under dusk or starlight conditions

2003 ◽  
Vol 93 (4) ◽  
pp. 315-322 ◽  
Author(s):  
H.E. Mellor ◽  
J.G.C. Hamilton
Keyword(s):  
Uv Light ◽  
Ultra Violet ◽  
Lutzomyia Longipalpis ◽  
Light Sources ◽  
Trap Design ◽  
Low Intensity ◽  
Violet Light ◽  
Males And Females ◽  
The Difference ◽  
And Control

AbstractThe responses of male and female Lutzomyia longipalpis (Lutz & Neiva) to different wavelengths of light was tested by presenting the sandflies with two light sources simultaneously, a series of test wavelengths between 350–670 nm and a 400 nm control. To test whether L. longipalpis could discriminate between the test and control, three sets of experiments were carried out in which the test wavelengths were presented at higher, equivalent or lower intensity than the control. In all three experiments, ultra-violet (350 nm) and blue-green-yellow (490–546 nm) light was more attractive to L. longipalpis than the control wavelength. However, at low intensity, UV was less attractive, than equivalent or higher intensity UV light. At intensities equivalent to or higher than the control wavelength, ultra-violet light was more attractive than blue-green. Furthermore, at low intensity, green-yellow (546 nm) light was more attractive to males whereas blue-green (490 nm) was more attractive to females. Blue-violet (400 nm) and orange-red (600–670 nm) light were least attractive in all three sets of experiments. Response function experiments indicated that the responses were dependent on both intensity and wavelength and that therefore more than one photoreceptor must be involved in the response. The results indicated that L. longipalpis can discriminate between different wavelengths at different intensities and thus have true colour vision. It also suggests that L. longipalpis may be able to navigate at dusk or under moonlight or starlight conditions using light in the blue-green-yellow part of the spectrum. The difference in response of males and females to light in this region is interesting and may indicate the different ecology of the sexes at night. Overall, these results may have important implications for sandfly trap design.

Cathodoluminescence of a 2 inch ultraviolet-light-source tube based on the integration of AlGaN materials and carbon nanotube field emitters

2019 ◽  
Vol 7 (37) ◽  
pp. 11540-11548 ◽  
Author(s):  
Wael Z. Tawfik ◽  
C. M. Manoj Kumar ◽  
Joonmo Park ◽  
Sang Kyun Shim ◽  
Hansung Lee ◽  
...  
Keyword(s):  
Carbon Nanotube ◽  
High Efficiency ◽  
Uv Light ◽  
Mass Scale ◽  
Light Sources ◽  
Scale Production ◽  
Basic Requirement ◽  
Field Emitters ◽  
Mass Scale Production ◽  
Technological Interest

High efficiency and mass-scale production ultraviolet (UV) light sources have become a basic requirement for various applications, and as such have attracted considerable technological interest.

scholarly journals Comparison on the Effect of different Light Sources on the Fate of 1,2,3,6-tetrahydro-N-(trichloromethylthio) phthalimide Using LCMS

2017 ◽  
Vol 1 (1) ◽  
pp. 28-33
Author(s):  
J. E. Ukpebor ◽  
E. E. Ukpebor
Keyword(s):  
Uv Radiation ◽  
Uv Light ◽  
Light Exposure ◽  
Uv Spectra ◽  
Light Sources ◽  
Photochemical Degradation ◽  
Experimental Conditions ◽  
Test Chemical ◽  
Uv C ◽  
Homolytic Dissociation

The photodegradation of 1,2,3,6-tetrahydro-N-(trichloromethylthio) phthalimide [captan -(CPT)] on apple surfaces by different UV radiation (UV-C -254 nm and full UV spectra – 250 – 750 nm) was investigated. Results obtained demonstrate the UV – light irradiance on apple surfaces has the capability of markedly reducing the concentration of surface sorbed levels of CPT (which is frequently detected on fruit surfaces) through direct and possibly indirect photochemical degradation. The loss of CPT was found to be significant for the experimental conditions described here, with >80% loss of initial concentrations of the test chemical under UV-B & C light within 30 minutes of light exposure. In general, CPT decayed more quickly under the UV A-B compared to UV –C. The rate of degradation (kCPT) was found to be 2.0 x 10-3 and 3.1 x 10-3 min -1 for the Xenon “750 W/m2” and UV-C lamps respectively with corresponding half-lives of 346.5 min and 22.57 min. Photolysis of CPT is usually as a result of the homolytic dissociation of a C-Cl bond.

Influence of MBE Growth Conditions on Dislocation Densities of GaAs/Ge Epilayers Grown on Silicon Substrates

1985 ◽  
Vol 43 ◽  
pp. 364-365
Author(s):  
K.M. Hones ◽  
P. Sheldon ◽  
B.G. Yacobi ◽  
A. Mason
Keyword(s):  
High Efficiency ◽  
Lattice Mismatch ◽  
Low Cost ◽  
Growth Conditions ◽  
Nonradiative Recombination ◽  
Device Structure ◽  
Si Substrates ◽  
Transmission Electron ◽  
Dislocation Densities ◽  
Dislocation Type

There is increasing interest in growing epitaxial GaAs on Si substrates. Such a device structure would allow low-cost substrates to be used for high-efficiency cascade- junction solar cells. However, high-defect densities may result from the large lattice mismatch (∼4%) between the GaAs epilayer and the silicon substrate. These defects can act as nonradiative recombination centers that can degrade the optical and electrical properties of the epitaxially grown GaAs. For this reason, it is important to optimize epilayer growth conditions in order to minimize resulting dislocation densities. The purpose of this paper is to provide an indication of the quality of the epitaxially grown GaAs layers by using transmission electron microscopy (TEM) to examine dislocation type and density as a function of various growth conditions. In this study an intermediate Ge layer was used to avoid nucleation difficulties observed for GaAs growth directly on Si substrates. GaAs/Ge epilayers were grown by molecular beam epitaxy (MBE) on Si substrates in a manner similar to that described previously.

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