BALLISTIC ELECTRON-TRANSPORT BEYOND 100-MU-M IN 2D ELECTRON-SYSTEMS

We have observed ballistic electron transport beyond 100 microm in the 2D electron system of an ultra-high mobility GaAs(AlGa)As heterostructure employing a magnetic electron focusing technique through wide point contacts. The amplitude of the characteristic magneto-oscillations is found to depend exponentially on electron propagation distance with a decay length λa = 15 microm. λa differs by about a factor of 2 from the mobility mean free path of 28 microm. This may indicate the determination of a different angular average of scattering events in focusing experiments as compared to standard mobility measurements. © 1990.