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.
Keywords
Cite
@article{arxiv.1906.11810,
title = {Shielded cantilever with on-chip interferometer circuit for THz scanning probe impedance microscopy},
author = {Matvey Finkel and Holger Thierschmann and Allard J. Katan and Marc P. Westig and Marco Spirito and Teun M. Klapwijk},
journal= {arXiv preprint arXiv:1906.11810},
year = {2019}
}
Comments
This 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