Nonradiative Recombination, Carrier Localization, and Emission Efficiency of AlGaN Epilayers with Different Al Content

The interplay between nonradiative recombination and carrier localization in Al x Ga 1− x N epilayers (0.11 < x < 0.78) was studied using the photoluminescence (PL) and light-induced transient grating (LITG) techniques. The carrier localization conditions were estimated from the temperature dependence of the PL band peak position. The room-temperature carrier lifetimes estimated by LITG were limited by the competition between the carrier localization and nonradiative recombination. Strong carrier localization was shown to be insufficient to achieve high internal quantum efficiency in AlGaN epilayers.