Effect of conduction band nonprabolicity on the Rashba spin splitting of AlGaN/GaN QWs

By using the perturbation expansion method and self-consistent iterative method, we evaluate the effect of the conduction band nonprabolicity on the wave vector (kt) dependent Rashba coefficient (α) and nonlinear Rashba spin splitting (ΔE) in the Al0.5Ga0.5N/GaN quantum well (QW). The effective mass (energy) under the first order approximation mt1 (Ek1) is in proximity to the iterative result mtp (Ekp) and mt1>mtp, Ek1Ekp>Ek1, so α0<αp<α1, ΔE0<ΔEp<ΔE1. With increasing kt, α decreases, and ΔE increases slowly. For small kt, α0 (ΔE0), α1 (ΔE1) and αp (ΔEp) are nearly the same. While for large kt, the difference between α0 and α1 (αp) increases rapidly, but the difference between ΔE0 and ΔE1 (ΔEp) increases slowly.