Voltage control of the quantum scattering time in InAs/GaSb/InAs trilayer quantum wells

We study the evolution of the quantum scattering time by gate voltage training in the topological insulator based on InAs/GaSb/InAs trilayer quantum wells. Depending on the minimal gate voltage applied during a gate voltage sweep cycle, the quantum scattering time can be improved by 50 % from 0.08 ps to 0.12 ps albeit the transport scattering time is rather constant around 1.0 ps. The ratio of the quantum scattering time versus transport scattering time scales linearly with the charge carrier density and varies from 10 to 30, indicating Coulombic scattering as the dominant scattering mechanism. Our findings may enable to improve the residual bulk conductivity issue and help in observing helical edge channels in topological insulators based on InAs/GaSb quantum well heterostructures even for macroscopic devices.