Band-Gap Bowing Parameter of the Al x Ga 1- x N Derived from Theoretical Simulation

The band-gap energy and band-gap bowing parameter of the wurtzite AlGaN alloys are investigated numerically with the CASTEP simulation program. The simulation results suggest that the unstrained band-gap bowing parameter of the wurtzite AlGaN alloys is b = 0.353 ±0.024 eV. The simulation results also show that the width of the Al x Ga 1- x N top valence band at the Γ point decreases when the aluminum composition increases and has a value of 7.331 eV for the GaN ( x =0) and 6.132 eV for the AlN ( x =1).