Wavelength-dependent determination of the recombination rate coefficients in single-quantum-well GaInN/GaN light emitting diodes

The recombination rate coefficients (RRCs) A, B, and C in MOVPE-grown single-quantum-well light emitting diodes spanning the entire blue-green spectral range are determined by fitting efficiency curves and differential carrier lifetimes. The results show definite trends for each of the RRCs: A tendentially decreases with increasing wavelength, B definitely decreases, and C remains approximately constant. Therefore, the increase of the droop with increasing wavelength (the green gap problem) is rather due to the decrease of B than an increase of C. The determined values of C are shown to be similar to what has been predicted by others with first-principles computer simulations accounting for phonon-assisted Auger recombination. Samples grown on sapphire and silicon substrates are compared and show significant differences only for the RRC A, presumably due to the difference in threading dislocation density.