Electronic and optical properties of strained wurtzite GaN

Band structures of wurtzite GaN (alpha-GaN) under strains in the region -5%-5% are calculated in a tight-binding framework. The empirical scaling rule has been used for considering the effects of hydrostatic strains. The scaling indexes are determined by fitting the deformation-potential constants with other theoretical values. The band gap at Gamma point increases with the absolute value of strains. GaN turns to be of indirect band gap when strains reach 5%. The density of stales and the imaginary part of dielectric function (epsilon(2)(omega)) are studied. Both the shape and energy position of the highest peak in the epsilon(2)(omega) spectrum successively change with the strains. The real part of dielectric function, refractive index and the effects of the strains on them are also shown.