Recombination dynamics of localized excitons in Al1−xInxN epitaxial films on GaN templates grown by metalorganic vapor phase epitaxy

Recombination dynamics of excitons in nearly strain-free ${\mathrm{Al}}_{\text{1−x}}{\mathrm{In}}_x\mathrm{N}$ alloys on the GaN template were studied. Their band-gap energy showed a nonlinear dependence on the InN molar fraction $\mathrm{x,}$ and the bowing parameter was determined to be approximately $\text{−3.1\hspace{0.17em}}\mathrm{eV}.$ Most of the alloys exhibited an extremely diffused band-edge, and consequently exhibited huge Stokes-type shifts up to 1–2 eV and full width at half maximum of the luminescence peaks up to 0.5 eV. The results suggested enhanced material inhomogeneity in AlInN compared to InGaN alloys. Since the time-resolved photoluminescence signal showed a pronounced stretched exponential decay, the spontaneous emission was assigned as being due to the radiative recombination of excitons localized in disordered quantum nanostructures. The integrated PL intensity at 300 K was as strong as 29% of that at low temperature, showing a potential use of AlInN alloys as infrared-to-UV light emitters.