Abstract
The effect of tensile and compressive biaxial strain on the valence band structures around the valence band edge, for both cubic and hexagonal GaN, were analyzed using a tight-binding method, which took the spin-orbit interaction into account. Biaxial strain was induced in the (001) and (0001) plane for cubic and hexagonal GaN, respectively. The strain induced change in the band structures was qualitatively the same for two types of GaN, however, it was remarkably different compared with GaAs, due to the very small split-off energy in GaN. The advantages of tensile strained GaN semiconductor lasers were discussed.