Acoustoelectric charge transport in quasi-one-dimensional systems
type: CreativeWork
description: The study of electron transport in mesoscopic systems has recently turned to the observation of time dependent single electron e ects, where the electron transport is frequency locked to an external potential. Such devices are expected to form the basis of a standard of electric current, long sought after by the metrological community, to provide a representation of the ampere and to be compared with existing quantum standards of the volt and ohm. This thesis details new experimental investigations of one such system. The piezoelectric interaction between an acoustic wave travelling on the surface of a GaAs heterostructure and electrons in a quasi-1D sys- tem de ned therein generates a current which, under certain conditions, can be quantized in units of $\textit{e f}$ where $\textit{e}$ is the electron charge and $\textit{f}$ the surface acoustic wave frequency. The general conditions under which this $\textit{single electron acoustoelectric effect}$ is observable are studied, and experimental results presented which demonstrate that the e ffect represents a possible route towards a current standard. The precision of the e ffect is assessed in a variety of experimental situations and device geometries. Several ways to enhance the precision of the eff ect are presented. Firstly a weak counterpropagating SAW beam produces a dynamic tuning of the SAW potential. Observations of a quantized acoustoelectric current are then presented in novel etched-channel SAW devices which aff ord a more precise current by allowing better control over the channel geometry. The presently attainable precision of the technique is at the level of 10's of ppm. Detailed measurements are presented of the single electron acoustoelectric e ffect in a magnetic fi eld applied perpendicular to the two-dimensional electron gas. Commensurability oscillations are observed for the interval of current between acoustoelectric current plateaux when the cyclotron diameter and SAW wavelength are comparable…
abstract: The study of electron transport in mesoscopic systems has recently turned to the observation of time dependent single electron e ects, where the electron transport is frequency locked to an external potential. Such devices are expected to form the basis of a standard of electric current, long sought after by the metrological community, to provide a representation of the ampere and to be compared with existing quantum standards of the volt and ohm. This thesis details new experimental investigations of one such system. The piezoelectric interaction between an acoustic wave travelling on the surface of a GaAs heterostructure and electrons in a quasi-1D sys- tem de ned therein generates a current which, under certain conditions, can be quantized in units of $\textit{e f}$ where $\textit{e}$ is the electron charge and $\textit{f}$ the surface acoustic wave frequency. The general conditions under which this $\textit{single electron acoustoelectric effect}$ is observable are studied, and experimental results presented which demonstrate that the e ffect represents a possible route towards a current standard. The precision of the e ffect is assessed in a variety of experimental situations and device geometries. Several ways to enhance the precision of the eff ect are presented. Firstly a weak counterpropagating SAW beam produces a dynamic tuning of the SAW potential. Observations of a quantized acoustoelectric current are then presented in novel etched-channel SAW devices which aff ord a more precise current by allowing better control over the channel geometry. The presently attainable precision of the technique is at the level of 10's of ppm. Detailed measurements are presented of the single electron acoustoelectric e ffect in a magnetic fi eld applied perpendicular to the two-dimensional electron gas. Commensurability oscillations are observed for the interval of current between acoustoelectric current plateaux when the cyclotron diameter and SAW wavelength are comparable…
author: Cunningham, John
language: en
keywords: Physics
license: https://apollo8-f-pro.lib.cam.ac.uk/bitstreams/e8bb1f71-613f-477e-a00b-0fd1a38217fb/download
license: https://www.rioxx.net/licenses/all-rights-reserved/
license: https://apollo8-f-pro.lib.cam.ac.uk/bitstreams/1e52249a-3ff0-469a-89ba-9391262893c6/download
date published: 2000-05-09
date modified: 2026-07-22T22:24:30Z
provider: Cambridge University
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of Cambridge

PropertyValue
property ID: DOI
value: 10.17863/CAM.7051