Efficiency of True-Green Light Emitting Diodes: Non-Uniformity and Temperature Effects

Materials (Basel). 2017 Nov 18;10(11):1323. doi: 10.3390/ma10111323.


External quantum efficiency of industrial-grade green InGaN light-emitting diodes (LEDs) has been measured in a wide range of operating currents at various temperatures from 13 K to 300 K. Unlike blue LEDs, the efficiency as a function of current is found to have a multi-peak character, which could not be fitted by a simple ABC-model. This observation correlated with splitting of LED emission spectra into two peaks at certain currents. The characterization data are interpreted in terms of non-uniformity of the LED active region, which is tentatively attributed to extended defects like V-pits. We suggest a new approach to evaluation of temperature-dependent light extraction and internal quantum efficiencies taking into account the active region non-uniformity. As a result, the temperature dependence of light extraction and internal quantum efficiencies have been evaluated in the temperature range mentioned above and compared with those of blue LEDs.

Keywords: InGaN green LEDs; active region non-uniformity; extended defects; internal quantum efficiency; light extraction efficiency; modeling; temperature-dependent electroluminescence.