Local barrier heights on quantum wires determined by ballistic electron emission microscopy

Abstract

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 and wet chemical etching. After evaporation of a 70 Å Au film, wires are directly observed both in sample topography and BEEM current image. The BEEM current is found to be enhanced if the ballistic electrons are injected directly into the wire region. Measurements of local effective barrier heights yield increased values between the wires. In this case, the effective threshold for BEEM current detection is determined by the underlying AlGaAs layer. Thus, the quantum wires are also resolved in a barrier height profile.