Theoretical optical gain in InGaN quantum wells

The compositional fluctuations of In was found in InGaN/GaN quantum wells, and the localised states caused by the potential fluctuation might help the laser oscillation of the InGaN/GaN quantum well lasers. We have evaluated the optical gain of GaN based quantum well structures with localised states, taking into account the Coulomb interaction. The localised states are introduced in the well as quantum dot-like sub-band states. We have used the temperature Green’s function formalism to treat the many-body effects and have found a new excitonic enhancement of the optical gain involved the localised states. This enhancement is stronger than the conventional Coulomb enhancement. It might play an important role to reduce the threshold carrier density.