The Effects of Selective Doping on Electron Transport in Two-Dimensional Electron Gases

Author: Olsen, Ben Andrew

Year: 2006

Degree: Senior thesis (Major)

Advisor: Eisenstein, James P.

Committee Member: None, None

Option: Physics

DOI: 10.7907/2k1t-3g27

Abstract

Recent research on bilayer two-dimensional electron gasses (2DEG) indicates the possibility of excitonic superfluidity, though experiments have measured small dissipation due to motion of unpaired vortices. In regular superconductors, carriers flow without dissipation beacuse vortices are "pinned" by impurities. This research investigates the effects of C and Si dopants within the quantum well of a single quantum well 2DEG. These dopants are candidates for improving vortex pinning in bilayer 2DEG systems. Four C-doped samples, with dopant density ranging from 3.5 x 1014cm-3 to 2.5 x 1016 cm-3 , and one Si-doped sample, with 2.3 x 1015m-3 Si ions are studied by electron transport measurements as functions of magnetic field strength. We find that minima in longitudinal resistance as a function of filling factor 11 are wider and offset toward'S lower v in samples with higher doping. This widening and shift is shown by mimina up to a v that decreases with increasing C dopant density, but is not observed at all for minima in the Si-doped sample.

Files