BALLISTIC ELECTRON-TRANSPORT IN MACROSCOPIC 4-TERMINAL SQUARE STRUCTURES WITH HIGH MOBILITY

Ballistic electron transport characteristics are studied using macroscopic four-terminal square structures formed in high-mobility wafers (mu = 7.8 X 10(6) cm2/V s at 1.5 K). Ballistic transport over 200-mu-m can be detected as a negative peak in resistance around B = O T when four-terminal resistance is measured as a function of magnetic field. The ballistic mean free path (l(b)) of electrons is evaluated from the size dependence of the negative peak height. The estimated l(b) becomes 86-mu-m, which is approximately equal to a conventional mean free path calculated from carrier density and mobility of the wafer.