Wurtzite結構之Al(下標 x)Ga(下標 1-x)N的結構特性及帶性質的模擬分析

Abstract

Ⅲ-nitride semiconductors have attracted both academic and technological extensive research in recent years because they have many outstanding optical properties such as lower dielectric permittivity, wide range band-gap energy from the visible region to the near ultraviolet, and direct band-gap properties that give rise to high emitting performance. This article applies numerical simulation based on ab initio to calculate the structural characteristics and the band-energy properties for wurtzite Al(subscript x)Ga(subscript 1-x) N. From this research we find that the lattice constant of the Al(subscript x)Ga(subscript 1-x) in the ground state obtained from the minimizer energy is larger than that obtained from the Vegard's law. The deviation parameter δ is -0.056±0.004 A for lattice constant a and is -0.128±0.025 A for lattice constant c. In addition, we also calculate the direct band-gap energy based on those lattice constants obtained by this research. We find that the direct band-gap energy obtained with the lattice constant obtained from the minimizer energy is smaller than that obtained from the Vegard's law. The bowing parameter b is 0.957±0.026 eV under the situation of the minimizer energy, which is very close to b=1.0 eV obtained from experimental data. On the other hand, the bowing parameter is 0.298±0.040 eV under the situation of applying the Vegard's law, which is also close to b=0.353±0.024 eV obtained from Kuo et al. by numerical simulation.