Theoretical studies of low strain n-type GaN co-doped by Si and Sn

Abstract

Electronic properties of Si- and Sn-doped GaN were studied by the first-principles calculations. According to the calculated density of states (DOS and PDOS), it is found that both the substitutional Si and Sn act as shallow donors in GaN. Results from charge density difference contour maps and Milliken population analysis are in good agreement with the results from DOS. Formation energy, ionization energy, and bond length results show that co-doping of Si and Sn in GaN can reduce the strain, and thus increases the carrier mobility due to smaller distortion of the lattice. Finally, the optimum Si/Sn ratio in GaN is proposed.