The Rashba coefficient and Rashba spin splitting for the first subband of the Alo.5Gao.5N/GaN/ Alo.5Gao.5N quantum well （QW） with various sheet carrier densities （Ns） are calculated by solving Schr6dinger and Poisson equations self-consistently. The Rashba spin splitting for the first subband at the Fermi level is considerable and increases evidently with Ns, since the Rashba coefficient, especially the Fermi wave vector increase rapidly. With increasing Ns, the peak of the wave function for the first subband moves towards the left heterointerface, and the average electric field in the well increases, so the two dominant contributions coming from the well and the heterointerface increase. Therefore, the strong polarization electric field and high density of 2DEG in III-nitrides heterostructures are of great importance to a and make the Rashba spin splitting in A1GaN/GaN QWs comparable to that of narrow-gap III-V materials. The results indicate that the sheet carrier density is an important parameter affecting the Rashba coefficient and Rashba spin splitting in A1GaN/GaN QWs, showing the possible application of this material system in spintronic devices.
