Spatial resolution of ballistic electron emission microscopy measured on metal/quantum-well Schottky contacts

摘要

Au Schottky contacts on cleaved AlGaAs/GaAs/AlGaAs quantum wells (QWs) were used as precise nanometer-scale apertures to quantify the spatial resolution of ballistic electron emission microscopy (BEEM). Both the amplitude and width of the measured average BEEM current profiles showed systematic dependencies on the QW width and Au film thickness, indicating surprisingly large BEEM resolutions of ～12, ～16, and ～22 nm for Au film thicknesses of 4, 7, and 15 nm, respectively, but roughly independent of Au grain size. These measurements are consistent with theoretical models that include multiple hot-electron scattering at interfaces and in the bulk of the metal film.