%0 Journal Article
%T Suppression of bulk conductivity in InAs/GaSb broken gap composite quantum wells
%A Christophe Charpentier
%A Stefan F£żlt
%A Christian Reichl
%A Fabrizio Nichele
%A Atindra Nath Pal
%A Patrick Pietsch
%A Thomas Ihn
%A Klaus Ensslin
%A Werner Wegscheider
%J Physics
%D 2013
%I arXiv
%R 10.1063/1.4821037
%X The two-dimensional topological insulator state in InAs/GaSb quantum wells manifests itself by topologically protected helical edge channel transport relying on an insulating bulk. This work investigates a way of suppressing bulk conductivity by using gallium source materials of different degrees of impurity concentrations. While highest-purity gallium is accompanied by clear conduction through the sample bulk, intentional impurity incorporation lead to a bulk resistance over 1 M\Omega. This resistance was found to be independent of applied magnetic fields. Ultra high electron mobilities for GaAs/AlGaAs structures fabricated in a molecular beam epitaxy system used for the growth of Sb-based samples are reported.
%U http://arxiv.org/abs/1308.3375v2