In Ga N ∕ Ga N multiple-quantum-well (MQW) light-emitting diodes with varied InGaN quantum well thicknesses are fabricated and characterized. The investigation of luminous efficiency versus current density reveals a variety of efficiency droop behaviors. It is found that the efficiency droop can be drastically reduced by increasing the quantum well thickness of the MQW structures. On the other hand, relative internal quantum efficiency (IQE) measurements indicate that a thinner well results to higher IQEs owing to the greater spatial overlap of electron and hole distribution functions.
We produced an anodic aluminum oxide (AAO) structure with periodic nanopores on the surface of flip-chip blue light-emitting diodes (FC-BLEDs). The nanopores had diameters ranging from 73 to 85 nm and were separated by distances ranging from approximately 10 to 15 nm. The light extraction efficiency enhancement of the FC-BLEDs subjected to different durations of the second pore-widening process was approximately 1.6–2.9%. The efficiency enhancement may be attributed to the following mechanism: periodic nanopores on the surface of FC-BLEDs reduce the critical angle of total reflection and effective energy transfer from a light emitter into a surface plasmon mode produced by AAO.
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