Correlation between optical and electrical performance of mid‐ultraviolet light‐emitting diodes on AlN substrates

Mid-ultraviolet LEDs grown on AlN substrates with a range of quantum efficiencies and wavelengths spanning 250 to 280 nm have been investigated by time-resolved photoluminescence and electroluminescence. Through scaling of room temperature internal quantum efficiencies across all devices, radiative and nonradiative lifetimes are also estimated. General trends observed include an increase in PL lifetime for longer wavelength and higher external quantum efficiency devices, consistent with the increase in the estimated nonradiative life-time with increasing wavelength. Despite these trends, the external quantum efficiency of the devices increases only weakly with increasing wavelength from 258 to 279 nm, suggesting that optimization of radiative lifetime and injection efficiency also play an important role. (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)