Virtual scanning tunneling microscopy : a local spectroscopic probe of two-dimensional electron systems

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Two dimensional electron systems (2DESs) at semiconductor interfaces are a useful medium for studying complex physics due to their very low disorder and relative simplicity. Many interesting effects, such as the quantum Hall effect, have been discovered through transport measurements in such systems. Unfortunately, the interfacial nature of 2DESs and the related surface energy barrier means that directly accessing them from the surface is difficult. This has limited our understanding of theoretically-predicted, spatially-organized effects such Wigner-crystal microemulsions and quantum Hall stripes, which have been probed only indirectly. In this dissertation, we develop a new type of local probe that circumvents the surface barrier by tunneling into a 2DES from a second 2DES grown nearby. The interlayer tunneling happens directly below a scanned metal tip outside the sample, behaving as a virtual tip in a system we call Virtual Scanning Tunneling Microscopy (VSTM). In the first half of the dissertation, we discuss a novel mechanism for tuning tunneling locally between two 2DESs. Its premise is that raising a quantum potential well next to an adjacent barrier is energetically similar to lowering the barrier relative to a fixed well. A lower barrier leads to the quantum well wave function extending into it and to increased tunneling into a second quantum well on the opposite side. We characterize this mechanism in a GaAs-AlGaAs heterostructure as a new type of transistor. In the second half of the dissertation, results from a working VSTM system are presented, with local interlayer tunneling revealing hidden features in the interfaces below the surface.


Type of resource text
Form electronic; electronic resource; remote
Extent 1 online resource.
Publication date 2012
Issuance monographic
Language English


Associated with Sciambi, Adam Richard
Associated with Stanford University, Department of Applied Physics
Primary advisor Goldhaber-Gordon, David, 1972-
Primary advisor Lev, Benjamin
Thesis advisor Goldhaber-Gordon, David, 1972-
Thesis advisor Lev, Benjamin
Thesis advisor Moler, Kathryn A
Advisor Moler, Kathryn A


Genre Theses

Bibliographic information

Statement of responsibility Adam Richard Sciambi.
Note Submitted to the Department of Applied Physics.
Thesis Ph.D. Stanford University 2012
Location electronic resource

Access conditions

© 2012 by Adam Richard Sciambi
This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).

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