In this work, we have investigated the compensation effect of defects in lightly Si-doped GaN layer. It is found that the compensation of defects can be enhanced by increasing Si doping concentration and dislocation density in GaN layer. Subsequently, through theoretical analysis it is found that a more effective compensation is activated by increasing Si doping, which is mainly due to the enhanced effect of deep defects in the compensation role rather than by the increase of density of deep defects. Meanwhile, it is found that the yellow luminescence (YL) intensity of lightly Si-doped GaN samples increases with the increasing Si doping concentration, which can also be caused by the enhancement of compensation of deep level defects, while the increase of peak intensity of band edge luminescence with increasing Si doping is mainly caused by the increase of free carriers.
