Mung bean has been reported to have antioxidant, antidiabetic, anti-inflammatory, and antitumor activities. Various factors have important effects on the types and contents of plant chemical components. In order to study quality of mung bean from different light sources, mung bean seedlings were exposed to red light-emitting diodes (LEDs) and ultraviolet-B (UV-B). Changes in the growth paramete...

In this study, we investigated the improvement in the light output power of indium gallium nitride (InGaN)-based ultraviolet (UV), blue, and green light-emitting diodes (LEDs) by fabricating shallow periodic hole patterns (PHPs) on the LED surface through laser interference lithography and inductively coupled plasma etching. Noticeably, different enhancements were observed in the light output p...

This paper presents a UV lithography method that utilizes a UV-LED (ultraviolet light-emitting diode) array as a micropatterning light source for high aspect ratio polymer microstructure fabrication. The sidewalls of commercial 5-mm-diamater UV-LEDs were coated with an opaque polymer to suppress the side propagation of UV light and to enhance UV collimation, resulting in a maximum flare angle o...

Light extraction efficiency (LEE) of AlGaN-based nanorod deep ultraviolet (UV) light-emitting diodes (LEDs) is numerically investigated using three-dimensional finite-difference time-domain simulations. LEE of deep UV LEDs is limited by strong light absorption in the p-GaN contact layer and total internal reflection. The nanorod structure is found to be quite effective in increasing LEE of deep...

Low-pressure mercury UV (LP-UV) lamps have long been used for bacterial inactivation, but due to certain disadvantages, such as the possibility of mercury leakage, deep-UV-C light-emitting diodes (DUV-LEDs) for disinfection have recently been of great interest as an alternative. Therefore, in this study, we examined the basic spectral properties of DUV-LEDs and the effects of UV-C irradiation f...

Ultraviolet (UV) fluorescent lamps are widely used in the manufacturing process of biomaterials. The possibility of replacing these lamps with ultraviolet light emitting diodes (UV-LEDs) was investigated and the results are presented here. A number of emission characteristics, including the spectral output and intensity of both light sources were measured and compared. The warm up time of the U...

The best approach when tackling any new topic is to begin with a study of relevant terminology within the context of the defined subject matter. Without a firm grasp of the common language, key concepts often appear disconnected, and it can be difficult to achieve full comprehension or communicate effectively within the marketplace. With emerging technologies such as UV Light Emitting Diodes (L...

Te ch ni ca l P ap er UV-LED Overview Part II — Curing Systems By Jennifer Heathcote This article is the second installment in a three-part series designed to consolidate key principles and technical information regarding the science and engineering behind ultraviolet light-emitting diodes (UV-LEDs). If you have not yet read “Part I— Operation and Measurement” in the July/August 2010 issue, you...

We report on the effect of GaN buffer threading dislocation (TD) optimization and InGaN/GaN quantum well (QW) hydrogen ðH2Þ treatment on the efficiency of GaN light emitting diodes (LEDs) operating in the spectral range from 400 to 500 nm. A tenfold reduction of the TD density in the GaN buffer increased the efficiency of blue LEDs operating at high current density, while in green LEDs it had v...

We present results on enhancement of 460 nm blue and 340 nm UV optical power output in III-nitride light emitting diodes ~LEDs! using photonic crystals ~PCs! under current injection. Triangular arrays of the PCs with diameter/periodicity of 300/700 nm were patterned using electron-beam lithography and inductively coupled plasma dry etching. The total power at 20 mA of 3003300 mm unpackaged LED ...