Time-resolved photoluminescence of GaN/Al0.5Ga0.5N quantum wells

We report photoluminescence (PL) and time-resolved PL measurements of ${\mathrm{GaN/Al}}_x{\mathrm{Ga}}_{\text{1−x}}\mathrm{N}$ multiple quantum wells with barriers of high aluminum content, $\text{x=0.5.}$ In wells of width 1–2 nm, low temperature recombination appears to be dominated by radiative processes with lifetimes ∼0.5 ns. Dependence of lifetime on emission energy is very small compared to InGaN quantum wells, 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.