Tunable transport properties of dual-gated InAs/GaSb core/shell nanowires

Dual-gate structures were fabricated on a single high-quality InAs/GaSb core/shell nanowire, enabling control of the band structure and Fermi level in the crossed bandgap heterostructure. The nanowire was grown using the molecular-beam-epitaxy method in a pure crystal phase for both the core and the shell. We demonstrated clear ambipolar transport characteristics derived separately from n-type InAs and p-type GaSb. A relatively high resistance region was found between n- and p-type conduction regions; the entrance to an energy gap was thus indicated. The gap's size varied with the electric fields of dual gates and could even be closed; after closure, a weak and non-vanishing energy gap appeared. The reopened energy gap was considerably suppressed in an in-plane magnetic field only when the field was perpendicular to the axis of the nanowire (i.e., the current direction) and was identified as an electron–hole interaction induced hybridization gap.