Dissertations, Theses, and Capstone Projects
Date of Degree
2-2015
Document Type
Dissertation
Degree Name
Ph.D.
Program
Physics
Advisor
Myriam P. Sarachik
Subject Categories
Physics
Keywords
2D electron system, strongly-correlated, thermopower, Wigner crystal
Abstract
Si-MOSFETs are basic building blocks of present-day integrated circuits. Above a threshold gate voltage, a layer of two-dimensional electrons is induced near the silicon-silicon dioxide interface of a Si-MOSFET. According to theory for noninteracting and weakly interacting electrons, no metallic state can exist in two dimensions in zero magnetic field in the limit of zero temperature. However, in strongly interacting electron systems the observation of a resistivity that changes from metallic to insulating temperature dependence has fueled a debate over whether this signals a quantum phase transition to a metallic phase in two dimensions.
In this thesis I will present the results of two detailed experimental studies performed on high mobility Si-MOSFET samples. In the first study, we find the thermopower of this low-disorder, strongly interacting 2D electron system in silicon diverges at a finite disorder-independent density, providing evidence that this IS a transition to a new phase at low densities. For the second study, we conducted measurements on I-V characteristics as well as the AC voltage generated by the sample in the insulating phase. Nonlinear I-V characteristics observed in the insulating phase have been attributed to the presence of an additional conduction channel due to a sliding electron solid (Wigner crystal). We seek to provide evidence for the presence of a zero-field Wigner solid by detecting the noise generated by the sliding crystallites.
Recommended Citation
Li, Shiqi, "Strongly-correlated 2D Electron Systems in Si-MOSFETs" (2015). CUNY Academic Works.
https://academicworks.cuny.edu/gc_etds/587