Electrostatic force balance microscopy

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.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Electrical & Computer Engr

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2015

Author dc:creator

• Bordain, Yemaya Candace

Contributors dc:contributor

• Liu, Gang L
• Cangellaris, Andreas C.
• Choquette, Kent D.
• Lyding, Joseph W.
• Sammann, Ernest

• electrostatic
• force
• balance
• equipotential
• null
• scanning
• imaging
• microscopy
• electric
• Kelvin
• heterodyne

Statement dc:rights

• Copyright 2015 Yemaya Candace Bordain

Language dc:language

en

Handle dc:identifier

http://hdl.handle.net/2142/78644

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/78644