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Title:Electrostatic force balance microscopy
Author(s):Bordain, Yemaya Candace
Director of Research:Liu, Gang L
Doctoral Committee Chair(s):Liu, Gang L
Doctoral Committee Member(s):Cangellaris, Andreas C.; Choquette, Kent D.; Lyding, Joseph W.; Sammann, Ernest
Department / Program:Electrical & Computer Eng
Discipline:Electrical & Computer Engr
Degree Granting Institution:University of Illinois at Urbana-Champaign
Degree:Ph.D.
Genre:Dissertation
Subject(s):electrostatic
force
balance
equipotential
null
scanning
imaging
microscopy
electric
Kelvin
heterodyne
Abstract:It is difficult to imagine a more flexible platform for nanoscale instrumentation design than the modern atomic force microscope (AFM). The basic AFM instrument allows studies of localizing phenomena at the nanoscale using an atomically sharp tip with precise positioning control, an exquisitely sensitive scheme for measuring tiny forces using a flexible cantilever with laser deflection sensing, and a system to record and display measurements during a raster or line scan. Forces of electrical, magnetic, or chemical origin can be detected. Moreover, the tip can be used to transfer forces, fields, or matter to a sample at a precise location. Exploiting this versatility has often required the addition of innovative electronics, new types of probes, and new methods for data acquisition and processing. As an application of force sensing for electrical characterization of nanoscale materials, we propose a novel microscopy scheme with the purpose of electrostatically imaging biased conductors buried in insulators below doped semiconductors. This Heterodyne-Electrostatic Force Balance Microscope (H-EFBM) uses a capacitive microcantilever to electrically stimulate thin layers of doped semiconductors, locally depleting the layer to create a “virtual aperture” while simultaneously sensing the electrostatic force exerted on the tip by the electric potential of the conductors buried in the oxide. The operating principles of this tool are described with support of multiphysics and numerical simulations as well as proof-of-concept experimental results. Although the tool described was unsuccessful at controllably depleting semiconductor materials, an intermediate step in detecting metal wires below thin layers of silicon, we demonstrate imaging of the surface potential and the combined dielectric constant and surface topography information of conducting materials. As with so many other AFM extensions, considerable engineering is required to make the new methods possible. Some highlights of that effort are presented.
Issue Date:2015-04-23
Type:Thesis
URI:http://hdl.handle.net/2142/78644
Rights Information:Copyright 2015 Yemaya Candace Bordain
Date Available in IDEALS:2015-07-22
Date Deposited:May 2015


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