Recent Developments in InGaN-Based Blue Leds and Lds

Abstract

UV/blue/green/amber InGaN quantum-well structure light-emitting diodes with an external quantum efficiency of 7.5%, 11.2%, 11.6%, and 3.3% were developed. The localization in the InGaN well layer induced by the In composition fluctuations seems to be a key role of the high efficiency of those InGaN-based light-emitting diodes. When the electrons and holes are injected into the InGaN active layer of the light-emitting diodes, these carriers are captured by the localized energy states before they are cap- tured by the nonradiative recombination centers caused by the large number of threading dislocations. InGaN multi-quantum-well structure laser diodes ' with modulation doped strained-layer superlattice cladding layers grown on the epitaxially lateral overgrown GaN substrate were demonstrated to have an estimated lifetime of more than 10000 hours under-room temperature con- tinuous-wave operation. When the laser diode was formed on the GaN layer above the SiO2 mask region without any threading dislocations, the thresh- old current density was as low as 2.7 kA cm -2 . When the laser diode was formed on the window region with the high threading dislocation density, the threshold current density was as high as 4.5 to 9 kA cm -2 . A leakage current