Enhancement of spin-orbit interaction and the effect of interface diffusion in quaternary InGaAsP/InGaAs heterostructures

The enhancement of spin-orbit interaction due to simultaneous control of both valence-band offset and electron probability density of the conduction band in a quaternary InGaAsP/InGaAs heterointerface is demonstrated. Weak antilocalization is measured to determine the strength of the Rashba spin-orbit interaction with different gate bias voltages and analyzed by quantum correction of the conductance developed by L. E. Golub [Phys. Rev. B 71, 235310 (2005)]. The Rashba spin-orbit interaction parameter is increased up to α=10.4× 10^-12 eVm with sheet carrier density N _s=2×10¹¹ cm^-2. To confirm such a strong effective magnetic field by comparison with the Zeeman energy, we also measure weak antilocalization in the presence of the in-plane magnetic field. A weak antilocalization signal remains up to B₁ = 3.0 T, resulting in direct evidence of strong spin-orbit interaction in the InGaAsP/InGaAs heterostructure. By taking the interface diffusion at the InGaAsP/InGaAs into account, the obtained Rashba spin-orbit interaction parameter α is found to be quantitatively consistent with theoretical calculation derived from the k·p theory.