Carrier transport and localization in a one-dimensional electronic system over liquid helium

Abstract

The carrier mobility in a nearly one-dimensional electronic system over liquid helium is measured. One-dimensional conducting channels are created by using the curvature of the surface of liquid helium covering a profiled dielectric substrate and applying a clamping electric field, which holds the electrons on the bottom of the liquid troughs. Measurements are made in a temperature interval of 0.5–1.6 K at linear densities in the range (0.5–2.5)×104 cm−1 at a generator voltage of 2–200 mV. It is shown that for a clean substrate the mobility of the electrons is governed by their interaction with helium atoms in the vapor and with ripplons; the results of the measurements are in satisfactory agreement with a theoretical calculation that assumes no localization. It is found that for substrates carrying a charge or having defects on the surface, the electron mobility decreases in comparison with the value for a clean substrate, and at temperatures T<1 K is either practically independent of temperature or decreases slightly as the temperature is lowered. It is observed that the frequency of the plasma waves propagating in the system of conducting channels decreases as the electron mobility decreases. The observed effects can be explained by localization in the one-dimensional electronic system in a random potential and the diffusive motion of the carriers in hops from one localized state to another.