Micro-EL studying of high power blue LEDs

The micro electro-luminescence (EL) investigation of high-power blue flip-chip LEDs at high currents has been performed. The studied distribution of the spectral EL characteristics over the LED emitted area allowed evaluating the current crowding effect and revealed the local overheating of the p-n junction. The current crowding effect lead to the two times higher local EL intensity. The local p-n junction temperature distribution was calculated from FWHM map using obtained value a FWHM temperature coefficient. Maximum local junction temperature was by 50 K higher than average value over the LED area. The high local temperature and high local current density can lead to device failure or drastically decreases the LED lifetime. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)