Anlage Research Group |
| High Frequency Superconductivity, Microscopy, Nanophysics, and Chaos |
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Historically, measurement of microwave properties of materials has involved use of resonant systems in which at least one dimension of the device was comparable to the wavelength of the radiation of interest. Consequently the sample studied is either bathed in a quasi-uniform electromagnetic field, or it is of size comparable to the wavelength. As a result the measurement yields an average of the properties over the sample, weighted by the current or field distribution on/in the sample. This is unsatisfactory, particularly when the sample is not homogeneous, or when the properties near the regions of strong field concentration (i.e. edges and corners of a sample) are not of interest. Our group was the first to recognize this difficulty and develop quantitative measurements of microwave properties at length scales far shorter than the free space wavelength, giving birth to the field of quantitative near-field microwave microscopy.
Our mcroscopes have been developed to quantitatively image metallic sheet resistance, dielectric permittivity, ferroelectric polarization, surface topography, tip-sample capacitance, magnetic permeability, ferromagnetic resonance field/frequency, and superconducting nonlinearities. The microscopes are broad-band and have demonstrated contrast down to the nm length scale. Several comprehensive review articles have been written by the group (see below). More details and discussion about near-field microwave microscopes can be found elsewhere on this site. Also RF current imaging in superconducting microwave devices has been accomplished by means of laser scanning microscopy.
Here is a popular summary of our microwave microscope technology.
Our near-field microwave microscope has been commercialized for quantitative dielectric imaging metrology. Keysight is producing a commercial scanning microwave microscope similar to ours (data sheet).
Links to our other pages on Microwave Microscopy
Nonlinear Properties of Superconductors
nm Resolution Microwave Microscopes
Local Linear and Nonlinear Dielectric Microwave Microscopy
Laser Scanning Microscopy of RF Currents in Superconducting Microwave Devices
Our work is supported by the National Science Foundation and the Maryland Center for Nanophysics and Advanced Materials.
Some relevant Review Articles on Microwave Microscopy : (All papers can be downloaded from the full publication list)
86. Steven M. Anlage, D. E. Steinhauer, B. J. Feenstra, C. P. Vlahacos, and F. C. Wellstood, "Near-Field Microwave Microscopy of Materials Properties," in Microwave Superconductivity, ed. by H. Weinstock and M. Nisenoff, (Kluwer, Amsterdam, 2001), pp.239-269. pdf
114. Steven M. Anlage, Vladimir V. Talanov, Andrew R. Schwartz, "Principles of Near-Field Microwave Microscopy," in Scanning Probe Microscopy: Electrical and Electromechanical Phenomena at the Nanoscale, Volume 1, edited by S. V. Kalinin and A. Gruverman (Springer-Verlag, New York, 2007, ISBN: 978-0-387-28667-9), pages 215-253. published preprint
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