Rashba and Dresselhaus spin-orbit coupling in GaN-based heterostructures probed by the circular photogalvanic effect under uniaxial strain

Abstract

The spin splitting in GaN-based heterostructures has been investigated by means of circular photogalvanic effect experiments under uniaxial strain. The ratios of Rashba and Dresselhaus spin-orbit coupling coefficients (R/D ratios) have been measured in AlxGa1−xN/GaN heterostructures with various Al compositions. It is found that the R/D ratio increases from 4.1 to 19.8 with the Al composition of the AlxGa1−xN barrier varied from 15% to 36%. The Dresselhaus coefficient of bulk GaN is experimentally obtained to be 0.4 eV Å3. The results indicate that the spin splitting in GaN-based heterostructures can be modulated effectively by the polarization-induced electric fields.