Imaging electrostatic microconstrictions in long 1D wires

We present scanned gate microscopy (SGM) images of a 4 mum long one-dimensional (1D) wire, The wire was defined by split-gate surface electrodes over a GaAs/AlGaAs heterostructure incorporating a subsurface 2D electron system. To generate SGM images, a charged tip scans a rectangular region over the wire. The wire conductance is recorded to determine the image contrast. A chain of circular features are seen along the length of the wire, caused by electrostatic microconstrictions. The microconstrictions were studied by changing either the tip voltage or the wire lateral position. (C) 2002 Elsevier Science B.V. All rights reserved.