Scanning Microwave Microscopy
Activities of the SMM group in the RF&Microwave Laboratory
Positioning of a sample for electrical measurement using our home-built near-field scanning microwave microscope
Characterization of Material Parameter at micron and submicron Scales
Near field scanning microwave microscopy (NFSMM) is a fairly novel measurement technique that combines an atomic force microscope (AFM) with a vector network analyzer (VNA). With an NFSMM one can measure simultaneously surface topography and electromagnetic properties of materials with sub-micrometer resolution. METAS is active in this area since 2011. As of today we are operating a home-built NFSMM and have participated in various projects to test the applicability of the NFSMM for a variety of measurement tasks. We characterized a wide range of materials, such as doped III-V semiconductors, solar cells, nanostructured materials, nano devices, 2D materials and piezoelectric materials. Most importantly, we also developed new calibration algorithms allowing for quantitative measurements with uncertainties.
If you are interested in characterizing electrical properties of your samples/devices (frequency range between 0-50 GHz), please write to us at firstname.lastname@example.org with a subject: "Characterize samples with NFSMM". A member of our team will get in touch with you.
Scheme of n-doped GaAs staircase sample
SMM cross section scan of n-doped GaAs staircase sample. Topography on the left, phase of S11 on the right.
Development of Impedance Standards for NFSMM
In a contrast to the currently available calibration kits, which only include capacitive standards, METAS provides a complete set of standards, including inductive and resistive circuits. With resistance and inductance between 0-960 Ohm and 0-1.15nH, respectively, and capacitive devices in the fF range.
If you are interested in these special calibration kits or would like to have your own customized ones, please write to us at email@example.com with a subject: "Calibration standards for NFSMM". We are also providing consulting services on calibration standards design and fabrication.
Impedance standard: top-view SEM image of of a three-ring resistive/inductive structure.
2d x-y scan with SMM of impedance standard. Shown are topography on the left and magnitude of S11 on the right.
Development of Next-Generation NFSMM
Currently the calibration of an NFSMM is not transferable, which means: a tip calibrated with calibration standards on one sample cannot be used for quantitative measurements performed on another sample. This limits the applications of the NFSMM for quantitative measurements. METAS tries to overcome this limitation by using a coaxial tip. The objective is to achieve better shielding of parasitic electromagnetic fields and thus reduce their influence in measurements.
METAS developed tip holder with gold-coated coaxial tip and tuning fork.
User-friendly GUI developed by METAS using Python and the Qt framework.
If you have plans to build your own NFSMM system, do not hesitate to contact us at firstname.lastname@example.org with a subject: "Development of NFSMM". A NFSMM matching your requirements can be designed, assembled, tested and installed for you. Consulting services are also available.
Scanning microwave microscopy applied to semiconducting GaAs structures
A. Buchter, J. Hoffmann, A. Delvallée, E. Brinciotti, D. Hapiuk, C. Licitra, K. Louarn, A. Arnoult, G. Almuneau, F. Piquemal, M. Zeier, F. Kienberger; Review of Scientific Instruments 89 (2018) 023704
Measuring Low Loss Dielectric Substrates with Scanning Probe Microscopes
J. Hoffmann, G. Gramse, J. Niegemann, M. Zeier, F. Kienberger; Applied Physics Letters, Vol 105, Issue 1, pp 013102 - 013102-4, July 2014
A Calibration Algorithm for Near field Scanning Microwave Microscopes
J. Hoffmann, M. Wollensack, M. Zeier, J. Niegemann, H.P. Huber, F. Kienberger; 12th IEEE Conference on Nanotechnology, Birmingham, Conference Publication, 2012
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