Photoluminescence of GaN Quantum Wells with AlGaN Barriers of High Aluminium Content

Abstract

We report photoluminescence and time-resolved photoluminescence measurements of GaN multiple quantum wells (QWs) with AlxGa1–xN barriers of high aluminium content. GaN/Al0.8Ga0.2N samples were grown with well widths as low as one monolayer, giving photoluminescence of peak energy 5.03 eV (247 nm) at room temperature. A study of lifetimes in GaN/Al0.5Ga0.5N samples shows low temperature recombination to be dominated by radiative processes with lifetimes ≈︂0.5 ns in 1 to 2 nm wells. Dependence of lifetime on emission energy is very small compared to InGaN QWs, indicating that carrier localization is very slight and interface quality is high. In 4 nm wells, PL emission at an energy below the bulk GaN band gap and long recombination lifetimes result from the polarization field across the wells.