Performance comparison of Nb and NbN Antenna-coupled microbolometers

C. Dietlein, Arttu Luukanen, Jari S. Penttilä, Hannu Sipola, Leif Grö nberg, Heikki Seppä, Panu Helistö, E. N. Grossman

Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientificpeer-review

7 Citations (Scopus)


We report the experimental results of a comparison between free-standing Nb and NbN microbolometer bridges coupled to equiangular spiral antennas on Si substrates. Because of the difference in material resistivity, bolometer resistance and aspect ratio is varied independently. Room-temperature antenna patterns measured at 650 GHz with a backwardwave oscillator are presented, as are I-V curves at T = 300 K and at T= 4 K. At room temperature, zero-bias resistance and specific responsivity are examined, and at 4 K, normal-state resistance and saturation power are studied. Nb devices display significantly lower saturation powers than NbN devices whose dimensions have been adjusted to provide equal resistance. However, for both materials, the inferred thermal conductances are higher than predicted by the Wiedemann-Franz relation, by approximately a factor of ¡­2 for Nb and a factor of ¡­5 for NbN. In general, and especially for the room-temperature responsivity, the substantial spread in parameters from device to device exceeds any systematic difference in performance between the materials.
Original languageEnglish
Title of host publicationTerahertz for Military and Security Applications V
PublisherInternational Society for Optics and Photonics SPIE
ISBN (Print)978-0-8194-6671-6
Publication statusPublished - 2007
MoE publication typeA4 Article in a conference publication
EventSPIE Defense and Security Symposium. Terahertz for Military and Security Applications V - Orlando, Florida, United States
Duration: 9 Apr 200710 Apr 2007

Publication series

SeriesProceedings of SPIE


ConferenceSPIE Defense and Security Symposium. Terahertz for Military and Security Applications V
CountryUnited States
CityOrlando, Florida


  • Bolometer
  • Millimeter-wave
  • Terahertz

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