The contribution of sidewall light extraction to efficiencies of polygonal light-emitting diodes shaped with laser micromachining

The light extraction efficiencies of InGaN/GaN blue light-emitting diodes (LEDs) of different geometries ranging from a triangle to a decagon have been simulated by ray-tracing. The conventional rectangular LED was found to be the most inefficient among the investigated polygons, and light extraction through the device sidewalls was the key factor. The results were experimentally verified by fabricating LEDs shaped into polygons by nanosecond-pulsed laser micromachining, which proved the simulated results. The mechanism of light extrac-tion in polygonal LEDs is discussed in detail. © 2010 American Institute of Physics.published_or_final_versio

Laser micro-machining of three-dimensional microstructures in optical materials

We demostrate an advanced precision cutting tool using a 349 nm nanosecond pulsed UV laser micromachining setup. After expansion and collimation, the laser beam is directed vertically and focused with a high performance triplet lens. With an Al mirror inserted in the path of the convergent beam, the beam can be focused on a horizontal machining plane at any desired tilting angles. Microstructures of a wide range of geometries on hard materials can be formed using this custom machining method. Conventional linear and rotary machining on sapphire materials have been demonstrated.published_or_final_versionThe 2009 Spring Meeting of the Materials Research Society (MRS), San Francisco, CA., 13-17 April 2009. In Materials Research Society Symposium Proceedings, 2009, v. 1179, p. 99-10

Laser micromachining of optical microstructures with inclined sidewall profile

Laser micromachining has been proved to be a useful tool for the formation of microstructures in semiconductor and optical materials. It is also widely adopted for dicing of light-emitting diode chips. The authors propose a modified laser micromachining setup which enables three-dimensional structures to be formed. A mirror is inserted in the optical path between the focusing optics and the machining plane so that the beam strikes the sample at an oblique angle. By translating and/or rotating the sample as micromachining is carried out, various three-dimensional structures such as a pyramid or a conic section can be obtained. Trenches as small as 10 μm on sapphire have been realized with nanosecond ultraviolet laser pulses. Laser-induced damage, due to resolidification of the ablation melt, accumulates with increasing scans of the beam; it can be removed by chemical and mechanical treatment. © 2009 American Vacuum Society.published_or_final_versio

Hodgkin's lymphoma as a second cancer in multiple myeloma never exposed to lenalidomide.

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Laser micro-machining of three-dimensional microstructures in optical materials

We demostrate an advanced precision cutting tool using a 349 nm nanosecond pulsed UV laser micromachining setup. After expansion and collimation, the laser beam is directed vertically and focused with a high performance triplet lens. With an Al mirror inserted in the path of the convergent beam, the beam can be focused on a horizontal machining plane at any desired tilting angles. Microstructures of a wide range of geometries on hard materials can be formed using this custom machining method. Conventional linear and rotary machining on sapphire materials have been demonstrated.published_or_final_versionThe 2009 Spring Meeting of the Materials Research Society (MRS), San Francisco, CA., 13-17 April 2009. In Materials Research Society Symposium Proceedings, 2009, v. 1179, p. 99-10

Microlens array on flip-chip LED patterned with an ultraviolet micro-pixelated emitter

A direct-write lithographic technique for the fabrication of micro-lens arrays with an ultraviolet (UV) micro-light-emitting diode (LED) array serving as an exposure source is reported. Polymer microlens arrays of high optical quality have been fabricated on the sapphire side of a flip-chip truncated-conic (TC) LED. The properties of the lenses are evaluated by optical microscopy and atomic force microscopy. The determined focal length is close to the predicted value. The effects of microlens integration on the optical properties of the LED are investigated. © 2011 IEEE.published_or_final_versio

A reliability study on green InGaN-GaN light-emitting diodes

In this letter, the reliability of green InGaN-GaN light-emitting diodes (LEDs) has been analyzed by correlating the defect density of wafers with various device parameters, including leakage current, 1/f noise, and degradation rate. It was found that as the wavelength of green LEDs increases from 520 to 550 nm by increasing the indium content in the quantum wells, the defect density also increases, thus leading to larger leakage current, enhanced noise magnitude, and shortened device lifetime. © 2009 IEEE.published_or_final_versio

A study on InGaN/GaN multiple quantum-well hydrogen sensor with HfTiO as gate dielectric

A hydrogen sensor based on InGaN/GaN multiple quantum wells (MQWs) was fabricated. A gate dielectric HfTiO was added to stabilize its performance at high temperature. Its hydrogen-sensing properties were studied at high temperatures from 100°C to 500°C. The sensor showed promising hydrogen-sensing properties over a wide temperature range, and could still function beyond 500°C. ©2009 IEEE.published_or_final_versionThe IEEE International Conference of Electron Devices and Solid-State Circuits (EDSSC 2009), Xi'an, China, 25-27 December 2009. In Proceedings of EDSSC, 2009, p. 127-13

The Fabry disease-associated lipid Lyso-Gb3 enhances voltage-gated calcium currents in sensory neurons and causes pain

Fabry disease is an X-linked lysosomal storage disorder characterised by accumulation of glycosphingolipids, and accompanied by clinical manifestations, such as cardiac disorders, renal failure, pain and peripheral neuropathy. Globotriaosylsphingosine (lyso-Gb3), a deacylated form of globotriaosylceramide (Gb3), has emerged as a marker of Fabry disease. We investigated the link between Gb3, lyso-Gb3 and pain. Plantar administration of lyso-Gb3 or Gb3 caused mechanical allodynia in healthy mice. In vitro application of 100nM lyso-Gb3 caused uptake of extracellular calcium in 10% of sensory neurons expressing nociceptor markers, rising to 40% of neurons at 1μM, a concentration that may occur in Fabry disease patients. Peak current densities of voltage-dependent Ca(2+) channels were substantially enhanced by application of 1μM lyso-Gb3. These studies suggest a direct role for lyso-Gb3 in the sensitisation of peripheral nociceptive neurons that may provide an opportunity for therapeutic intervention in the treatment of Fabry disease-associated pain

Passivation of Oxide Traps and Interface States in GaAs Metal-Oxide-Semiconductor Capacitor by LaTaON Passivation Layer and Fluorine Incorporation

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