Quantum well thickness dependence of spin orbit interaction in gated InP/In_0.8Ga_0.2As/In_0.52Al_0.48As asymmetric quantum wells

We have investigated the influence of the quantum well (QW) thickness for the gate controlled Rashba spin orbit interaction (SOI) in InP/In_0.8Ga_0.2As/In_0.52Al_0.48As asymmetric QWs from the analysis of the weak antilocalization. We prepared two different samples with 5 and 10 nm In_0.8Ga_0.2As QWs. Gate bias dependence of the Rashba SOI parameter α shows inverse dependence between 5 and 10 nm QWs, where the α for 5 nm QW increases while that for 10 nm QW decreases with increasing the gate bias voltage. By comparing the obtained α with the interface and the field contributions of Rashba SOI calculated by the k·p formalism, the opposite dependence of the α is resulted in the enhancement of the interface contribution in 5 nm QW due to the large electron probability at the InP/In_0.8Ga_0.2As interface, whereas the dominant contribution for the α is originated from the In_0.8Ga_0.2As field contribution in 10 nm QW.