Nonlinear optical properties of double asymmetric Al_xGa_1−xN/GaN quantum wells considering strain effects

A theoretical study has been carried out to investigate the optical absorption coefficient and the relative change in the refraction index in asymmetric double zinc-blende Al_xGa_1−xN/GaN quantum wells. Highlighting the effect of lattice strain on these properties.
The electronic energy structure is determined in the scheme of the effective mass and parabolic band approximations while the strain effects are incorporated with the use of the model solid theory. Optical coefficients are calculated through the expressions obtained within the compact matrix density formulation. In general we conclude that the strain effects are of paramount importance for the cubic phase of the considered heterostructure, because this contribution considerably affect the band offset of the system and, despite the ground, and the first excited, state are not modified significantly, the studied optical properties becomes slightly affected, particularly for narrow well widths.