Ballistic transport at room temperature in deeply etched cross-junctions

We measured the transmission through manoscopic cross-junctions at variable temperature and bias. The devices were prepared by deep etching through a two-dimensional electron gas in InGaAs/InP samples. Our experiments show th at the transmission characteristic is partly ballistic even at room tempera ture. The measurements are analysed in terms of an equivalent network, and the involved resistances are related to the electrons' mean free path. Diff erent scattering mechanisms are considered to account for the transition fr om ballistic to diffusive transport.