Indium incorporation effects on luminescence mechanisms in quaternary AlInGaN layers

The optical and structural properties of quaternary AlInGaN layers grown by a pulsed metalorganic chemical vapor deposition (PMOCVD) have been investigated by means of photoluminescence (PL) and time-resolved PL (TRPL) measurements and X-ray diffraction. The AlInGaN layers show strong blueshift and linewidth broadening of the PL emission band with increasing excitation power. With increasing indium mole fraction, the AlInGaN layer exhibited a stronger PL intensity, a faster PL decay, and a smaller lattice mismatch between the AlInGaN layer and the GaN buffer layer. Based on both the PL and TRPL data, we suggest that the incorporation of indium creates more band-tail states and enhances the luminescence efficiency, indicating that the PMOCVD-grown AlInGaN is better suited as the active region material for ultraviolet light-emitting diodes than conventional MOCVD-grown AlInGaN.