Electron transport in mis-like gaAs/Al_xGa_1-xAs heterostructures with nanostructured gates

A novel approach to realize quasi-one-dimensional electron gases with high electron densities using an undoped GaAs/Al_xGa_1-xAs heterostructure is studied. The quasi-one-dimensional electron gas is field effect induced via a narrow top gate and the electrons are extracted from ion-implanted ohmic regions. The wires are characterized by low temperature magnetotransport experiments. The quasi-one-dimensional nature of the transport manifests itself in the observed depopulation of the one-dimensional subbands in a magnetic field perpendicular to the heterointerface and a model is presented to obtain a realistic estimation of the density distribution underneath the narrow gate and to determine the effective wire width. The effective width is found to be comparable to the gate width. Finally, the applicability of this approach to design electron-electron coupling structures is demonstrated by studying samples containing a narrow split across the gate.