Quantized conductance of ballistic constrictions in InAs/AlSb quantum wells

Split-gate ballistic constrictions have been fabricated on InAs/AlSb quantum-well heterostructures. Sharp conductance steps of 2e2/h are observed at 4.2 K, while conductance plateaus persist up to 30 K. The sharp features and high temperature operation are made possible by the low effective mass (m*Γ= 0.023me) of InAs, and the closeness of the quantum well (20 nm) to the wafer surface.