Localized States and Quantum Spin Hall Effect in Si-Doped InAs/GaSb Quantum Wells

Dong-Hui Xu, Jin-Hua Gao, Chao-Xing Liu, Jin-Hua Sun, Fu-Chun Zhang, Yi Zhou

Published 2013-10-15, updated 2014-01-19Version 2

We study localized in-gap states and quantum spin Hall effect in Si-doped InAs/GaSb quantum wells. We propose a model describing donor and/or acceptor impurities to describe Si dopants. This model shows in-gap bound states and wide conductance plateau with the quantized value $2e^2/h$ in light dopant concentration, consistent with recent experiments by Du et al. We predict a conductance dip structure due to backward scattering in the region where the localization length $\xi$ is comparable with the sample width $L_y$ but much smaller than the sample length $L_x$.