Ga Desorption Kinetics in the Molecular Beam Epitaxy of AlGaN Nanowires for Ultrashort Wavelength Light-Emitting Diodes

In this work, we show that by growing AlGaN nanowires with molecular beam epitaxy (MBE) in a Ga highly desorbing regime, light-emitting diodes that can emit light at 209 nm are obtained. Detailed light emission characteristics and transmission electron microscopy studies indicate that such a light emission is due to the formation of AlN. The correlation between Ga desorption and electroluminescence (EL) is further investigated by using a unique approach with two different Al sources. It is found that the Ga desorption related to the surface-migrated Ga adatoms along the nanowire sidewall drastically affects the device EL properties, rather than the impinged Ga adatoms on the nanowire top surface. The unveiled correlation between the Ga desorption kinetics and EL properties could advance the development of technically important, ultrashort, wavelength-tunable semiconductor ultraviolet light-emitting diodes using AlGaN nanowires.