Abstract
Although the high efficiency above 300 lm/W is achieved for white LED in laboratory, the commercial LED approaches half of the maximum. Efficiency droop (ED) is still a serious problem for high-power applications. In this chapter, some techniques to achieve high internal quantum efficiency (IQE) for GaN-based LEDs are presented. The effects of defects and polarization are discussed in detail. The IQE of green and deep ultraviolet-LEDs are particularly concerned. In the IQE measurement, the general temperature-dependent photoluminescence method is analyzed, and some significant developments are introduced to obtain a more accurate value. The exact origins of ED are still on debates. We tend to attribute the droop to various origins for different situations. At last, we give some remedies to alleviate the droop. Radiative recombination rate enhancement may be more important for low-droop LEDs. Localized surface plasmon and nanocavity may be the potential candidates for novel low-droop devices.
Published Version
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