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High-power truncated-inverted-pyramid (AlxGa1-x)0.5In0.5P/GaP light-emitting diodes exhibiting ≫50% external quantum efficiency

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20 Author(s)
Krames, M.R. ; Hewlett-Packard Optoelectronics Division, Materials R&D Department, San Jose, California 95131 ; Ochiai-Holcomb, M. ; Hofler, G.E. ; Carter-Coman, C.
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A truncated-inverted-pyramid (TIP) chip geometry provides substantial improvement in light extraction efficiency over conventional AlGaInP/GaP chips of the same active junction area (∼0.25 mm2). The TIP geometry decreases the mean photon path-length within the crystal, and thus reduces the effects of internal loss mechanisms. By combining this improved device geometry with high-efficiency multiwell active layers, record-level performance for visible-spectrum light-emitting diodes is achieved. Peak efficiencies exceeding 100 lm/W are demonstrated (100 mA dc, 300 K) for orange-emitting p∼610 nm) devices, with a peak luminous flux of 60 lumens (350 mA dc, 300 K). In the red wavelength regime p∼650 nm), peak external quantum efficiencies of 55% and 60.9% are measured under direct current and pulsed operation, respectively (100 mA, 300 K). © 1999 American Institute of Physics.

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Applied Physics Letters  (Volume:75 ,  Issue: 16 )