Many-body effects on optical gain in strained hexagonal and cubic GaN/AlGaN quantum well lasers

Abstract

Theoretical results on the optical gain of strained hexagonal and cubic GaN/AlGaN quantum well (QW) lasers taking into account of many-body effects are presented. These results are also compared with those of the free-carrier theory without the many-body effects. The band structure is calculated by using the Hamiltonian based on the Rashba–Sheka–Pikus 6×6 Hamiltonian. It is found that the peak gain for cubic and hexagonal QW lasers is increased by about 45% and 37%, respectively, near the transparency carrier density due to the Coulomb enhancement. Also, the gain peaks with many-body effects are redshifted relative to those without many-body effects by ∼130 meV at higher carrier densities. These results indicate the importance of the many-body effects for both cubic and hexagonal GaN/AlGaN QW lasers.