BALLISTIC-ELECTRON-EMISSION MICROSCOPY IN LIQUID-HELIUM USING LOW-DIMENSIONAL COLLECTOR ELECTRODES

We report ballistic electron emission microscopy (BEEM) studies which show that a GaAs/AlGaAs heterostructure provides a very efficient coll ector electrode at 4.2 K. The enhanced thermal resolution at low tempe rature is utilized to determine the BEEM current threshold behavior ve ry accurately. We find that diffusive scattering processes dominate th e carrier transport across the Au/GaAs interface. Quantum wire regions on laterally structured samples are clearly identified with BEEM. The BEEM current is strongly enhanced on top of the quantum wires. (C) 19 96 American Institute of Physics.