Marked enhancement of 320–360 nm ultraviolet emission in quaternary InxAlyGa1−x−yN with In-segregation effect

We demonstrated room-temperature (RT) intense ultraviolet (UV) emission in the wavelength range of 315–370 nm from quaternary InxAlyGa1−x−yN alloys grown by metalorganic vapor-phase epitaxy. We found that the UV emission is considerably enhanced by the In-segregation effect upon introducing 2%–5% of In into AlGaN. The In incorporation in quaternary InxAlyGa1−x−yN is markedly enhanced with the increase of Al content when using a relatively high growth temperature (830–850 °C), resulting in efficient RT UV emission. Maximally efficient emission was obtained at around 330–360 nm from the fabricated quaternary InxAlyGa1−x−yN (x=2.0%–4.8%,y=12%–34%). The intensity of the 330 nm emission from quaternary In0.034Al0.12Ga0.85N was as strong as that of the 430 nm emission from In0.22Ga0.78N at RT. We clearly observed In segregation of submicron size from cathode luminescence images of quaternary InAlGaN films.