Investigation of defect-related optical properties in AlxInyGa1−x−yN quaternary alloys with different Al/In ratios

AlxInyGa1−x−yN quaternary alloys with different ratios of Al/In were grown by metal-organic chemical vapor deposition on GaN/Al2O3 substrates. The structural and emission properties of the as-grown samples were investigated, respectively, by high-resolution X-ray diffraction and photoluminescence (PL) measurements. The PL emission character is related to the two prominent quenching bands, which have been determined to be located at around 1.1 eV and 1.7 eV above the valence band, respectively, by the method of optical quenching of photoconductivity. PL emission is most intense when the Al/In ratio is 7.5 for the AlxInyGa1−x−yN layer. In addition, a stronger quenching phenomenon with Al/In ratio of 5.0 in AlxInyGa1−x−yN is observed in accordance with a reduction of the intensity of AlxInyGa1−x−yN-related emission peak.