A moisture- electrical - temperature (MET) test is proposed to evaluate the outdoor reliability of high power blue LEDs, with and without phosphor, and to understand the degradation physics of LEDs under the environment of combined humidity, temperature and electrical stresses. The blue LEDs with phosphor will be the high power white LEDs. Scanning acoustic microscopy is used to examine the res...

The effect of strongly-imbalanced carrier concentration and mobility on efficiency droop is studied by comparing the onset voltage of high injection, the onset current density of the droop, and the magnitude of the droop, as well as their temperature dependence, of GaInN-based blue and green light-emitting diodes (LEDs). An n-to-p asymmetry factor is defined as σn/σp, and was found to be 17.1 f...

With the recent development of ultraviolet light emitting diodes (UV-LEDs), it is now possible to apply UV disinfection, previously used only for medium-to-large sized sewage treatment plants, Johkasou wastewater, a household wastewater system. However, known that coliforms have been inactivated by irradiation regain their activity after sunlight irradiation, etc. Therefore, in small Johkasou, ...

We demonstrate the feasibility of polycrystalline nitride semiconductor light-emitting diodes ~LEDs!. Here, polycrystalline LEDs were deposited on quartz substrates, incorporating a layer structure identical to that used for epitaxially grown LEDs. The deposition exhibits a tendency to produce c-oriented crystallites. Violet-blue ~430 nm! operation of a polycrystalline LED is demonstrated, with...

by Michael Keene, Design Engineer Endicott Research Group, Inc. Abstract As LED backlights continue to displace CCFLs in LCDs, display manufacturers have to deal with several important decisions regarding the choice and arrangement of these LEDs and how best to drive them. One major decision is whether to use a large number of low-power LEDs, or a smaller number of mediumto high-power LEDs. The...

In recent years, LED (light-emitting diode) has been the subject of research within the field of plant growth and development. However, there has been little discussion about using LED in vitro cultures of Panax vietnamensis, one of the important medicinal plants belonging to the Panax genus. This study examines the influence of various LED lamps on callus growth and plant formation of P. vietn...

The commonly observed absorption around 265 nm in AlN is hampering the outcoupling efficiency of light-emitting diodes (LEDs) emitting UV-C regime. Carbon impurities nitrogen sublattice (CN) are believed to be origin this absorption. A specially tailored experiment using a combination ion implantation boron, carbon, and neon with subsequent high-temperature annealing allows separate influence i...

Catalyst-free p-n homojunction ZnO nanowire (NW) arrays in which the phosphorus (P) and zinc (Zn) served as p- and n-type dopants, respectively, have been synthesized for the first time by a controlled in situ doping process for fabricating efficient ultraviolet light-emitting devices. The doping transition region defined as the width for P atoms gradually occupying Zn sites along the growth di...

In the exposure process of photolithography, a free-form lens is designed and fabricated for UV-LED (Ultraviolet Light-Emitting Diode). Thin film metallic glasses (TFMG) are adopted as UV reflection layers to enhance the irradiance and uniformity. The Polydimethylsiloxane (PDMS) with high transmittance is used as the lens material. The 3-D fast printing is attempted to make the mold of the lens...