Multi-terminal ballistic transport in one-dimensional wires

Recent experiments (Yacoby et al., Phys, Rev. Lett. 77 (1996) 4612; Solid State Commun. 101 (1997) 77; M. Rother et al., ICPS-24, Th-P137) have shown non-universal conductance quantization in one-dimensional wires that are fabricated using the cleaved edge overgrowth technique (L.N. Pfeiffer ct al., Microelectronics J. 28 (1997) 817). In one of the papers (Yacoby ct al., Phys, Rev. Lett. 77 (1996) 4612), it was speculated that the origin of the reduced conductance lies in the interface between the one-dimensional wire and the two-dimensional electron gas regions, which serve as ohmic contacts and thermal reservoirs. Here we report the results of a systematic study of such 2D-1D interfaces. By embedding a 2D-1D interaction section region of controllable length inside an otherwise isolated wire, we were able to study the properties of the coupling between these two subsystems. Our results show that 2D-1D interface is in fact the origin of the non-universal conductance. (C) 2000 Elsevier Science B.V. All rights reserved.