Quantum well thickness dependence of Rashba spin-orbit coupling in the InAs/InGaAs heterostructure

We have investigated the quantum well thickness dependence of spin-orbit coupling in InAs/InGaAs heterostructures. The beat patterns of the oscillatory magnetoresistance were measured to determine the magnitude of the parameter of an inverted type InAs quantum well structures with the thicknesses ranging from 2 to 7 nm. The band energies, electronic charge distribution, and Rashba spin-orbit coupling parameter of the structure were calculated using a self-consistent field method and a kP perturbation scheme. The magnitude of the parameter increases with decreasing the InAs quantum well thickness. Comparison with the calculated data revealed that the increase in the spin-orbit interaction parameter is due to the stronger penetration of the wave function envelope into the barriers where more pronounced band bending and barrier asymmetry occur in both the conduction and valence bands.