Cubic GaN films on GaAs (001) substrates without deep-level luminescence grown by metalorganic vapor phase epitaxy

Cubic GaN films on GaAs (001) substrates which show a low-temperature photo luminescence (PL) without the deep-level orange (2.0 to 2.1 eV) band were g rown by metalorganic vapor phase epitaxy (MOVPE). The orange luminescence r ecovers its relative intensity at room temperature, though the dominance of band-edge free exciton is still significant. The surface morphology was mu ch smoother and the inclusion of hexagonal phase was much reduced for the s amples with the suppressed orange band. It is suggested that the role of th e GaN buffer layer is very essential in the optimized growth for high optic al quality films, providing a flat cubic structure template as well as avoi ding thermal damage of GaAs surface at high temperatures.