Theory of non-polar and semi-polar nitride semiconductor quantum-well structures

Abstract

We investigate the electronic and optical properties of non-polar a- and m-planes and semi-polar InGaN–GaN quantum-well structures using the multiband effective-mass theory taking into account the many-body effects. These results are compared with those of (0 0 0 1) oriented c-plane wurtzite InGaN–GaN quantum wells. We derive explicitly the valence-band Hamiltonian and interband optical matrix elements with polarization dependence for an arbitrary crystal polar angle θ and an azimuthal angle φ. The average hole effective masses of the topmost valence band along the wave vector perpendicular to the crystal orientation for the non-polar and semi-polar cases are substantially lower than that of the c-plane case. It is found that the azimuthal angle φ does not change the shape of the band structure but shifts the sub-band position. Thus the transition energy will be dependent on both the polar angle θ and the azimuthal angle φ. It is expected that the optical matrix elements are strongly anisotropic and optical gain would be larger for the non-polar and semi-polar cases because of the vanishing of the internal electric fields.