Branchline and directional THz coupler based on PECVD SiNx-technology

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A fabrication technology to realize THz microstrip lines and passive circuit components is developed and tested making use of a plasma-enhanced chemical vapor deposition grown silicon nitride (PECVD SiNx) dielectric membrane. We use 2 μm thick SiNx and 300 nm thick gold layers on sapphire substrates. We fabricate a set of structures for thru-reflect-line (TRL) calibration, with the reflection standard implemented as a short through the via. We find losses of 9.5 dB/mm at 300 GHz for a 50 Ohm line. For a branchline coupler we measure 2.5 dB insertion loss, 1 dB amplitude imbalance and 21 dB isolation. Good control over the THz lines parameters is proven by similar performance of a set of 5 structures. The directional couplers show -14 dB transmission to the coupled port, -24 dB to the isolated port and -25 dB in reflection. The SiNx membrane, used as a dielectric, is compatible with atomic force microscopy (AFM) cantilevers allowing the application of this technology to the development of a THz near-field microscope.
Original languageEnglish
Title of host publication41st International Conference on Infrared, Millimeter, and Terahertz waves, IRMMW-THz 2016
EditorsPeter Uhd Jepsen
Place of PublicationPiscataway, NJ
Number of pages2
ISBN (Electronic)978-1-4673-8485-8
Publication statusPublished - 1 Dec 2016
EventIRMMW-THz 2016: 41st International Conference on Infrared, Millimeter, and Terahertz Waves - Bella Center, Copenhagen, Denmark
Duration: 25 Sept 201630 Sept 2016
Conference number: 41


ConferenceIRMMW-THz 2016
Abbreviated titleIRMMW-THz
Internet address


  • Microstrip
  • Fixtures
  • Coplanar waveguides
  • Couplers
  • Standards
  • Probes
  • Dielectrics


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