ONE-DIMENSIONAL TRANSPORT AND GATING OF INAS GASB STRUCTURES/

Semimetallic InAs/GaSb structures are known to contain simultaneously both two dimensional electrons in the InAs and two dimensional holes i n the GaSb layers. Following successful anodisation of undoped GaSb, w e describe transport measurements performed on a wide area gated sampl e and also a single quantum point contact. In the large area gated sam ple, the electron density increases and the hole density decreases whe n a positive gate voltage is applied. Under negative bias, an addition al layer of holes is created at the interface between the insulating a nd GaSb capping layers, which is confirmed by self-consistent modellin g of the band profile under external bias. The conductance of the poin t contact is found to exhibit quantised values.