Efficiency Improvement Progress in Green, Yellow and Red III Nitride LEDs
- Lumileds Lighting U.S., LLC, San Jose, CA (United States); Lumileds
- Lumileds Lighting U.S., LLC, San Jose, CA (United States)
- University of New Mexico
Large improvements in the efficiencies of visible light emitting diodes (LEDs) have been realized over the last decade. Extending the range of wavelengths over which efficient emission can be realized continues to be a goal of active research. Efficiency droop refers to a non-thermal decrease in internal quantum efficiency with increasing current density that affects III-nitride LEDs in general, but more severely those with longer emission wavelengths. The so-called green gap is mainly related to the wavelength dependence of efficiency droop. The peak EQE in commercial green LEDs exceeds 60% but corresponds to a current density that is an order of magnitude lower than required for applications.
In this presentation, we will review some of the underlying physics that contribute to the wavelength dependence of droop. We will discuss some challenges in the development of long wavelength III-nitride LEDs and possible strategies to mitigate efficiency droop based on the understanding that nonradiative Auger recombination is the root cause. One general strategy is to engineer the multi-quantum well active region to minimize the average carrier density. Another approach is to design wells with a more favorable balance between the radiative and Auger coefficients. Finally, we will present the current status of the performance of green, yellow and red III-Nitride LEDs.
- Research Organization:
- Lumileds LLC
- Sponsoring Organization:
- USDOE Office of Energy Efficiency and Renewable Energy (EERE), Energy Efficiency Office. Building Technologies Office
- DOE Contract Number:
- EE0009163
- OSTI ID:
- 1855312
- Report Number(s):
- DOE-Lumileds-0009163-1
- Country of Publication:
- United States
- Language:
- English
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