Band engineering in Al_(0.5)Ga_(0.5)N/GaN superlattice by modulating Mg dopant

摘要

The electronic structures of Mg modulation-doped and undoped Al_(0.5)Ga_(0.5)N/GaN superlattices (SLs) are investigated by using first-principles density function theory. The layer-projected densities of states indicate that the band alignment is changed from type I to type II and the band bending due to polarization is reduced significantly by modulating Mg dopant in AlGaN layer. It is further confirmed by the calculations of the partial charge density profiles and the valence band offsets where the valence-band maximum of AlGaN in Mg modulation-doped SL is located above that of GaN. The strong hybridization between N and Mg orbitals plays an important role on the upward shifts of the valence band edges.