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Search Publications by: Thomas Mitchell Wallis (Fed)

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Displaying 76 - 100 of 158

Radio-Frequency and DC Electrical Characterization on a Modular MEMS Mechanical Test Platform for Nanomaterials

June 16, 2013
Author(s)
J. J. Brown, Thomas Mitchell (Mitch) Wallis, Pavel Kabos, Kristine A. Bertness, Norman Sanford, Victor Bright
In order to enable radio frequency (RF) data collection from a micromechanical system designed to strain nanomaterials, a coplanar electrical waveguide has been integrated with an actuated microscale stage. RF (100 MHz to 20 GHz) admittance measurements

Spatially-Resolved Dopant Characterization with a Scanning Microwave Microscope

March 25, 2013
Author(s)
Thomas M. Wallis, Atif A. Imtiaz, Alexandra E. Curtin, Pavel Kabos, Matthew D. Brubaker, Norman A. Sanford, Kristine A. Bertness
The scanning microwave microscope (SMM) is a tool for spatially-resolved microwave characterization of nanoelectronic materials and devices. The microscope incorporates a sharp, near-field probe, which measures local changes in reflected microwave signals

Near-Field Scaning Microwave Microscope (NSMM)

December 31, 2012
Author(s)
Atif A. Imtiaz, Thomas M. Wallis, Pavel Kabos
Electromagnetic waves in the microwave frequency range are an essential tool for the investigation of material and device properties across a broad range of applications. Examples of materials of interest include: ferroelectric materials, ferromagnetic

Microwave Measurements and Systematic Circuit-Model Extraction of Nanowire Metal Semiconductor Field Effect Transistors

August 24, 2012
Author(s)
Dazhen Gu, Thomas M. Wallis, Pavel Kabos, Paul T. Blanchard, Kristine A. Bertness, Norman A. Sanford
We present detailed on-wafer scattering parameter measurements and equivalent circuit modeling of metal semiconductor field effect transistor (MESFET) that incorporates a GaN nanowire (NW). A systematic procedure is established to extract intrinsic model

Microwave measurements and systematic circuit-model extraction of nanowire metal semiconductor field-effect transistors

August 24, 2012
Author(s)
Dazhen Gu, Thomas M. Wallis, Pavel Kabos, Paul T. Blanchard, Kristine A. Bertness, Norman A. Sanford
We present detailed on-wafer scattering parameter measurements and equivalent circuit modeling of metal semiconductor field effect transistor (MESFET) that incorporates a GaN nanowire (NW). A systematic procedure is established to extract intrinsic model

A near-field scanning microwave microscope for characterization of inhomogeneous photovoltaics

August 10, 2012
Author(s)
Joel C. Weber, Kristine A. Bertness, John B. Schlager, Norman A. Sanford, Atif A. Imtiaz, Thomas M. Wallis, Pavel Kabos, Kevin J. Coakley, Victor Bright, Lorelle M. Mansfield
We present a near field scanning microwave microscope (NSMM) optimized for imaging photovoltaic samples. Our system incorporates a cut Pt-Ir tip inserted into an open ended coaxial cable to form a weak resonator, allowing the microwave reflection S11

A Direct Comparison System for Power Calibration up to 67 GHz*

July 1, 2012
Author(s)
Thomas M. Wallis, Thomas P. Crowley, Denis X. LeGolvan, Ronald A. Ginley
A direct comparison system for calibration of power sensors with 1.85 mm precision coaxial connectors up to 67 GHz has been developed. The comparison is implemented in two frequency bands. Between 10 MHz and 50 GHz, power sensors with 2.4 mm coaxial

Calibration Techniques for Scanning Microwave Microscopy

July 1, 2012
Author(s)
Thomas M. Wallis, Atif A. Imtiaz, Alexandra Curtin, Pavel Kabos, H. P. Huber, Joseph J. Kopanski, F. Kienberger
Two techniques are described for calibrating a scanning microwave microscope (SMM). The first technique enables spatially-resolved absolute capacitance measurements on the attofarad-to-femtofarad scale. The second technique enables profiling or dopant

A thickness-shear MEMS resonator employing electromechanical transduction through a coplanar waveguide

May 21, 2012
Author(s)
Ward L. Johnson, Thomas M. Wallis, Pavel Kabos, Eduard Rocas, Juan C. Collado Gomez, Li-Anne Liew, Albert Davydov, Alivia Plankis, Paul R. Heyliger
The design, modeling, fabrication, and characterization of a vibrationally trapped thickness-shear MEMS resonator is presented. This device is intended to avoid various limitations of flexural MEMS resonators, including nonlinearity, clamping losses

Frequency-selective contrast on variably doped p-type silicon with a scanning microwave microscope

May 14, 2012
Author(s)
Atif A. Imtiaz, Thomas M. Wallis, SangHyun S. Lim, H. Tanbakuchi, H-P Huber, A. Hornung, P. Hinterdorfer, J. Smoliner, F. Kienberger, Pavel Kabos
We report frequency dependent contrast in d(S11)/dV measurements of a variably doped p-type silicon sample in the frequency range from 2GHz to 18GHz. The measurements were conducted bys use of a scanning microwave microscope. The measurements were done at

Calibrated nanoscale dopant profiling using a scanning microwave microscope.

January 3, 2012
Author(s)
Pavel Kabos, Thomas M. Wallis, H P. Hubner, I. Humer, M. Hochleitner, M. Fenner, M. Moertelmaier, C. Rankl, Atif A. Imtiaz, H. Tanbakuchi, P. Hinterdorfer, J. Smoliner, Joseph J. Kopanski, F. Kienberger
The scanning microwave microscope (SMM) is used for calibrated capacitance spectroscopy and spatially resolved dopant profiling measurements. It consists of an atomic force microscope (AFM) combined with a vector network analyzer operating between 1-20 GHz
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