Differential Charge Carrier Lifetime Investigated In A Blue Ingan Led At Operational Conditions

Investigation to reveal the discrepancy appeared between the current-dependent differential charge carrier lifetime in the InGaN/GaN light emitting diodes (LEDs) active region at low current working conditions and that predicted by the ABC-model was conducted. Photoluminescence frequency-domain lifetime measurement technique using resonant small-signal optical excitation and detection from the LED active region -the quantum wells, was applied to investigate InGaN/GaN LED emitting light in the blue spectra region. When analyzing the dependencies of the differential lifetime tDLT vs. normalized optical output power p and obtaining the best fit, charge carrier escape time from the quantum well in the range of 100 - 150 ns was encountered. Finally, it turned out that the escape rate is rather influential and exceeding even the Shockley-Read-Hall recombination rate at low current condition. The consequences for the ABC-model and for the evaluation of the related recombination coefficients are discussed.