Reduction of gallium vacancy concentration in gallium nitride grown with preheated ammonia

The use of ammonia preheater reduces the Ga vacancy (V-Ga) concentration in GaN. The epilayers grown with or without preheated ammonia had little differences in structural properties from X-ray diffraction and transmission electron microscopy. It was found, however, that the GaN epilayers grown with unheated ammonia had more charge compensation centers. The intensities of yellow luminescence (YL) in GaN epilayers grown with preheated ammonia decreased with Si doping, whereas those grown with unheated ammonia increased with Si doping. It is suggested that the use of preheated ammonia reduced the VGa concentration in GaN without altering structural properties.