Study of gain mechanisms in AlGaN in the temperature range of 30–300 K

We report the results of an experimental study of the stimulated emission (SE) properties of AlGaN epilayers grown by metalorganic chemical vapor deposition under high optical excitation conditions in the temperature range of 30–300 K. The band gap and energy position of spontaneous and SE peaks were measured over the entire temperature range studied. Through an analysis of the temperature dependence of the relative energy positions and the SE threshold, combined with absorption and time-resolved photoluminescence measurements, we estimated the carrier density at threshold to be ∼1019 cm−3 throughout the temperature range studied. Such a high carrier density indicates that an electron-hole plasma is responsible for the generation of gain in this material system from 30 to 300 K. Issues related to the development of short-wavelength AlGaN-based light emitting devices are discussed.