Band-Gap Bowing Parameters of the Zincblende Ternary III–Nitrides Derived from Theoretical Simulation

The band-gap bowing parameters of unstrained zincblende ternary III–nitride alloys are investigated numerically with the CASTEP simulation program. Direct and indirect band-gap bowing parameters of 1.379 eV and 1.672 eV for In x Ga 1- x N, 0.755 eV and 0.296 eV for Al x Ga 1- x N, and 2.729 eV and 3.624 eV for Al x In 1- x N are obtained. Simulation results show that the direct band-gap energy is always smaller than its indirect counterpart for In x Ga 1- x N, indicating that the zincblende In x Ga 1- x N is a direct band-gap semiconductor. There is a direct-indirect crossover near x =0.571 for Al x Ga 1- x N, and x =0.244 for Al x In 1- x N. The relationship between band-gap energy and lattice constant for zincblende In x Ga 1- x N, Al x Ga 1- x N, and Al x In 1- x N is also provided.