LOCAL BARRIER HEIGHTS ON QUANTUM WIRES DETERMINED BY BALLISTIC-ELECTRON-EMISSION MICROSCOPY

In this letter, ballistic electron emission microscopy (BEEM) studies on quantum wire structures are reported. GaAs/AlGaAs heterostructures were laterally patterned with a period of 800 nm by laser holography a nd wet chemical etching. After evaporation of a 70 Angstrom Au film, w ires are directly observed both in sample topography and BEEM current image. The BEEM current is found to be enhanced if the ballistic elect rons are injected directly into the wire region. Measurements of local effective barrier heights yield increased values between thr wires. I n this case, the effective threshold for BEEM current detection is det ermined by thr underlying AlGaAs layer, Thus, the quantum wires are al so resolved in a barrier height profile. (C) 1996 American Institute o f Physics.