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 InxGa1-xN, 0.755 eV and 0.296 eV for AlxGa1-xN, and 2.729 eV and 3.624 eV for AlxIn1-xN are obtained. Simulation results show that the direct band-gap energy is always smaller than its indirect counterpart for InxGa1-xN, indicating that the zincblende InxGa1-xN is a direct band-gap semiconductor. There is a direct-indirect crossover near x=0.571 for AlxGa1-xN, and x=0.244 for AlxIn1-xN. The relationship between band-gap energy and lattice constant for zincblende InxGa1-xN, AlxGa1-xN, and AlxIn1-xN is also provided.