Characteristics of high Al content AlGaN grown by pulsed atomic layer epitaxy

► 3.7 μm Al0.91Ga0.09N epilayers was grown on sapphire (0 0 0 1) substrates by PALE. ► The crystalline quality of sample is better. ► The sample's Raman spectrum supports the results that asymmetric photoluminescence peak is caused by the exciton-phonon coupling. ► Deep ultraviolet photoluminescence spectroscopy and Raman scattering spectroscopy analysis show that there possibly exists a high density of deeper localized state (∼90 meV) as the center of radiative recombination.