Tensile strain effects on GaN-based quantum well lasers

The strain effects on optical gain and threshold current density in cubic G aN-based quantum well (QW) lasers are studied theoretically using the k.p m ethod with 6 x 6 Luttinger-Kohn Hamiltonian and the density matrix formalis m with intraband relaxation. Compared with compressive strained GaN-based Q W lasers, tensile strained QW lasers show improvements in optical gain, dif ferential gain, and threshold current density. This is mainly because tensi le strain in GaN-base QW laser increases dipole matrix element due to the v ery narrow spin-orbit (SO) split-off energy. In this study, tensile straine d GaN-based QWs are realized by introducing In-x(Ga1-yAly)(1-x)N for barrie r layers. Therefore, we can achieve cubic GaN-based QW lasers with better p erformance by using tensile strain rather than compressive strain.