Weak antilocalization and zero-field electron spin splitting in Al x Ga 1 − x N ∕ AlN ∕ GaN heterostructures with a polarization-induced two-dimensional electron gas

Spin-orbit coupling is studied using the quantum interference corrections to conductance in AlxGa1�xN / AlN/ GaN two-dimensional electron systems where the carrier density is controlled by the persistent photoconductivity effect. All the samples studied exhibit a weak antilocalization feature with a spin-orbit field of around 1.8 mT. The zero-field electron spin splitting energies extracted from the weak antilocalization measurements are found to scale linearly with the Fermi wave vector ESS =2 kf with an effective linear spin-orbit coupling parameter = 5.5 10 �13 eV m. The spin-orbit times extracted from our measurements varied from 0.74 to 8.24 ps within the carrier density range of this experiment.