Enhancement of Rashba coupling in vertical In0.05Ga0.95As/GaAs quantum dots

We study the spin-splitting energies in low-potential-barrier quantum dots, finding splitting energies that are orbital state dependent. The theoretical analysis is done with a generalization of the Fock-Darwin states in the presence of spin-orbit interactions. We discuss experimental evidence indicating that the Rashba interaction strength in vertical In${}_x$Ga${}_{1-x}$As/GaAs quantum dots is in the range 80 meV Å $⩽{\lambda }_R⩽$ 120 meV Å. This enhanced spin-orbit interaction can be understood from the high penetration of the electron wave function into the quantum well with low-potential barrier.