Du, Rui-Rui2011-07-252011-07-252010Knez, Ivan. "Quantum transport in inverted indium arsenide/gallium antimonide composite quantum wells." (2010) Master’s Thesis, Rice University. <a href="https://hdl.handle.net/1911/62155">https://hdl.handle.net/1911/62155</a>.https://hdl.handle.net/1911/62155We present a comprehensive study of low temperature quantum transport in double gated InAs/GaSb composite quantum wells. Recently, it has been proposed that this system in inverted regime should exhibit the topologically insulating (TI) phase, characterized by an energy gap in the bulk and gapless edge modes, protected from backscattering by time reversal symmetry. We sweep the Fermi level through the bulk mini-gap, observing resistance peaks and finding strong evidence for the existence of the mini-gap; however, the mini-gap does not show insulating behavior, with a residual bulk conductivity which is a few times larger then the expected contribution from the edge. Our data indicate, that bulk conductivity is not an issue of "dirt", which can be improved by simply reducing the amount of disorder, but a fundamental property of strongly coupled electron-hole systems in realistic materials, which must be considered in studies of proposed TI edge modes.application/pdfengCopyright is held by the author, unless otherwise indicated. Permission to reuse, publish, or reproduce the work beyond the bounds of fair use or other exemptions to copyright law must be obtained from the copyright holder.Condensed matter physicsThesisTHESIS PHYS. 2010 KNEZ