ABSTRACT
Carrier localization is a phenomenon substantially affecting the carrier dynamics in AlGaN epitaxial layers and quantum well structures. In this chapter, the origins of the carrier localization in AlGaN are discussed, the key experimental techniques for the study of this phenomenon and its influence on the efficiency of the radiative and nonradiative recombination of nonequilibrium carriers are presented, and the features important for practical applications of AlGaN are studied. The current status in the study of the peak photoluminescence efficiency and the efficiency droop at elevated excitation intensities in AlGaN and AlGaN-based heterostructures is presented. The importance of stimulated emission on carrier dynamics at high densities of nonequilibrium carriers is revealed. From the application point of view, the review is focused on the influence of carrier localization on the luminescence efficiency droop, which is of especial importance for the development of efficient deep UV LEDs, and on the peculiarities of the stimulated emission in high-aluminum-content AlGaN, which is prospective for the development of deep UV laser diodes still encountering substantial problems.
