Conductance oscillations periodic in the density of one-dimensional electron gases

Abstract

Results are reported of a detailed study of the conductance oscillations in one-dimensional (1D) Si inversion layers. A comparison is made with results for GaAs accumulation layers. The conductance oscillates by as much as a factor of 100 and is accurately periodic in the number of electrons per unit length. The period varies randomly from sample to sample, and changes when a single sample is warmed to room temperature and remeasured at low temperature. Multiple periods are often observed, and the amplitude of the individual frequency components can be altered by moving the electron gas from side to side with a transverse electric field. These observations suggest that the period is determined by the distance between charged defects near the 1D channel. Measurements of the temperature dependence indicate that the oscillatory conductance reflects a periodic energy for a thermally activated conductance mechanism as well as a parallel oscillatory tunneling mechanism. The period of the conductance oscillations is found to be surprisingly independent of magnetic field B. However, the random modulation of the amplitude of the oscillations is reduced by a B field normal to the semiconductor surface, as it is by increasing temperature. © 1990 The American Physical Society.