Collateral evidence for an excellent radiative performance of AlxGa1−xN alloy films of high AlN mole fractions

Recombination dynamics for the deep-ultraviolet (DUV) near-band-edge emission of AlxGa1−xN epilayers of high AlN mole fractions (x) are studied using time-resolved spectroscopy. Their low-temperature radiative lifetime (τR) is longer than that for the epilayers of low-x AlxGa1−xN, AlN, or GaN due to the contribution of bound and localized tail-states. However, τR shows little change with temperature rise, and the value is a few ns at 300 K. The results essentially indicate an excellent radiative performance of AlxGa1−xN alloys of high x, although the luminescence efficiency of AlxGa1−xN DUV light-emitting-diodes reported so far is limited by the short nonradiative lifetime.