Comparative analysis of structure and electronic properties of doped g-GaN/Al0.5Ga0.5N heterostructure

In this paper, the structure and electronic properties of Be-, Mg-, C-, N-, O- and S- doped g-GaN/Al0.5Ga0.5N heterostructures under N-rich and Ga-rich conditions are investigated based on DFT calculations. Computational results show that all dopants are more stable when doped at Ga site. Due to difference in electronegativity, the atomic structure and charge distribution in vicinity of dopants are significantly changed. The existence of built-in electric field at interface allows Al0.5Ga0.5N layer to transfer electrons into g-GaN layer. The results of band gap reveal that g-GaN/Al0.5Ga0.5N heterostructure before and after doping is direct band gap. Due to the introduction of dopants, impurity levels are created between conduction band and valence band to facilitate electron transfer. Meanwhile, doping under Ga-rich is more favorable for electron transfer and emission due to the lower band gap and work function.