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but they do get in the way of the electrons, making them slower.


Such a direct understanding of electric friction will be useful in the future for designing more efficient and faster electronics, and perhaps for finding new tricks to reduce electrical resistance.


Further details of this work has been published in the paper,”High-Field Transport in an Electron-Hole Plasma: Transition from Ballistic to Drift Motion”, by Bowlan et al, Phys. Rev. Lett. 107, 256602 (2011).


Epistar’s high voltage chipset breaks efficacy records


With its higher CRI, and competitive lm/$, the direct red platform is suited for use in warm white applications in retrofit, professional lighting, and luminaires


Epistar Lab has successfully developed a warm white efficacy of 216 lm/W at an operating current of 5 mA and CRI of 87 Ra at CCT of 2700K. Under a typical driving current of 15mA (or about 1 W operational equivalent), the luminous efficacy of 197 lm/W was achieved.


technologies in high voltage chips. These include a novel substrate transfer process, lower MQW light absorption and a structure for increasing the photon extraction efficiency. Improvements have also been made on current spreading uniformity, the MQW structure and IQE and lower forward voltage.


Prevaled Light Engines up to 70 percent more efficient


Osram has expanded its portfolio of LED light engines


Osram’s latest Prevaled LED Light Engine range now offers up to 70 percent more efficiency. The products of the Prevaled Core Eco Z2 line attain a module efficiency of up to 108 lumen/watt (lm/W).


With its LED Light Engines, Osram offers planning security whilst continually improving LED performance. The firm believes the dimensions, luminous flux and light distribution are the equivalent to the Edison socket in the analogue world of light.


The new Prevaled products are equipped with “Chip-on-Board technology”. In other words, individual LEDs are no longer mounted on the printed circuit board, but are placed to create a surface made of LED chips. This ensures homogenous light, as one no longer perceives the light of every single LED chip.


Osram says the Prevaled Core Eco Z2 can replace high pressure discharge lamps of up to 70W, energy saving lamps with up to 2 x 42W and halogen lamps, each with up to 100W power consumption, and therefore the traditional technologies in the majority of the spotlight and downlight applications.


Epistar Lab’s new record adopts several


What’s more, it is up to 70 percent more efficient than the previous Prevaled generation. The prerequisite for this, however, is the large portfolio ranging between 800 lm and 5,000


January / February 2012 www.compoundsemiconductor.net 79


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