Gate-controlled spin-orbit coupling in InAs/InGaAs quantum well structures.

: We have investigated gate electric field controlled Rashba spin-orbit coupling (SOC) constant (alpha) in In0.53Ga0.47As and InAs-inserted quantum well (QW) structures. More than three times larger gate controllability of a in the InAs-inserted QW has been observed compared to the In0.53Ga0.47As QW. The enhanced gate controllability of alpha directly results from the larger zero-field SOC in narrow band gap InAs QW. Furthermore, the lower contact resistance and higher electron mobility imply that the InAs QW is a more promising channel for spintronic device applications.