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 ( k t ) dependent Rashba coefficient ( α ) and nonlinear Rashba spin splitting (Δ E ) in the Al 0.5 Ga 0.5 N/GaN quantum well (QW). The effective mass (energy) under the first order approximation m t1 ( E k1 ) is in proximity to the iterative result m tp ( E kp ) and m t1 > m tp , E k1 E kp , showing the higher order contributions to m t ( E k ) are small. The sign of the nonparabolic correction to E k is just opposite to that of the correction to m t . The increase of α and Δ E due to the conduction band nonparabolicity reaches about 3% at k t =1 nm −1 . Around the left heterointerface, the probability density is high and E k0 > E kp > E k1 , so α 0 α p α 1 , Δ E 0 E p E 1 . With increasing k t , α decreases, and Δ E increases slowly. For small k t , α 0 (Δ E 0 ), α 1 (Δ E 1 ) and α p (Δ E p ) are nearly the same. While for large k t , the difference between α 0 and α 1 ( α p ) increases rapidly, but the difference between Δ E 0 and Δ E 1 (Δ E p ) increases slowly.