Transport in InAs/GaSb Composite Quantum Wells with an Oxide Top Barrier

InAs/GaSb composite quantum wells (CQWs) have now attracted much attentions with the exciting prospect that a variety of topological phases could be hosted in this material. Typical CQWs incorporate AlGaSb as top and bottom barriers by molecular epitaxy, providing nearly lattice - matched interfaces. On the other hand it may be desirable to replace AlGaSb barriers by oxide/ high - k* dielectrics for the purpose of enhancing gating functionality and device reliability. Here we report preliminary results of low temperature quantum transport on devices with an oxide top barrier, where the MBE grown AlGaSb barrier was removed by selective etching and an oxide layer was subsequently deposited by ALD. We will show the transport results of devices with ALD dielectrics including HfO₂/ZrO₂/Al₂O₃.