ELECTRON FOCUSING WITH MULTI-PARALLEL 1D CHANNELS

Electron focusing is observed in samples with simple multi-parallel quasi one-dimensional (1D) channels fabricated by two different processes: the damage creation technique using a focused ion beam (FIB) implantation and wet-chemical etching following electron beam (EB) lithography. The focusing peak intensity, normalized by zero field resistance, is only 11% for the implanted sample, whereas it reaches 35% for the wet-etched sample. This enhancement of the focusing peak intensity for the wet-etched sample seems due to the collimation of injected electrons. Utilizing the focusing peak intensity, specularity coefficients p for electrons reflected at the boundaries, defined by the FIB implantation and by the wet-chemical etching, are deduced as being 0.35 and ≅ 1, respectively. The ballistic mean free path for both samples is also evaluated to be the same value of about 2 μm. From the temperature dependence of the ballistic mean free path, it is proved that the focusing electrons are mainly scattered by the ionized remote impurities. © 1991.