Large conductance anisotropy in a novel two-dimensional electron system grown on vicinal (111)B GaAs with multiatomic steps

A novel selectively doped AlGaAs/GaAs heterojunction was successfully formed on a vicinal (111)B substrate, in which both quasiperiodic and aperiodic multiatomic steps with the average spacings of similar to 20 nm are introduced. It is found that the electrical conductance G(perpendicular to) of two-dimensional electrons across the steps is far lower than that of G(parallel to) along the steps and the ratio G(parallel to)/G(perpendicular to) exceeds 100 at 18 K. While G(parallel to) is almost independent of temperature T below similar to 70 K, G(perpendicular to) increases exponentially with 1/T with the activation energy of similar to 5 meV, indicating the presence of potential barriers for the electron motion across the aperiodic steps. (C) 1996 American Institute of Physics.