Shielded cantilever with on-chip interferometer circuit for THz scanning probe impedance microscopy

Abstract

We have realized a microstrip based THz near field cantilever which enables quantitative measurements of the impedance of the probe tip at THz frequencies (0.3 THz). A key feature is the on-chip balanced hybrid coupler which serves as an interferometer for passive signal cancellation to increase the readout circuit sensitivity despite extreme impedance mismatch at the tip. We observe distinct changes in the reflection coefficient of the tip when brought into contact with different dielectric (Si, SrTiO3) and metallic samples (Au). By comparing to finite element simulations we determine the sensitivity of our THz probe to be well below 0.25 fF. The cantilever further allows for topography imaging in a conventional atomic force microscope mode. Our THz cantilever removes several critical technology challenges and thus enables a shielded cantilever based THz near field microscope.

arXiv commentThis article has been submitted to Review of Scientific Instruments. After it is published, it will be found at https://aip.scitation.org/journal/rsi. 8 pages + supplementary material

References in corpus (10)

• Mott transition in VO2 revealed by infrared spectroscopy and nano-imaging
• First M87 Event Horizon Telescope Results. II. Array and Instrumentation
• Electrodynamics of Correlated Electron Materials
• Microwave imaging of mesoscopic percolating network in a manganite thin film
• Quantitative Imaging of Sheet Resistance with a Scanning Near-Field Microwave Microscope
• Broadband dielectric microwave microscopy on $\mu$m length scales
• Electrodynamics of correlated electron matter
• Spatial conductivity mapping of unprotected and capped black phosphorus using microwave microscopy
• Balanced superconductor-insulator-superconductor mixer on a 9~$\mu$m silicon membrane
• Analysis of a single-mode waveguide at sub-terahertz frequencies as a communication channel