Development of NbN THz HEB Mixer Devices and Films

Published

October 12, 2021

Author(s)

Eyal Gerecht, V. A. Bhupathiraju, John Nicholson, Dazhen Gu, Yan Zhuang, Fernando R. Morales, Xin Zhao, Ric Zannoni, Sigfrid Yngvesson

Abstract

Until recently, the thin-film NbN samples used by most PHEB research groups across the world have been produced in Moscow(MSPU). We have developed a process for fabricating thin NbN films at the National Institute of Standards and Technology (NIST) in Boulder, CO. A two-fold approach has been taken. The first is to maximize the critical temperature at the expense of IF bandwidth and noise temperature. With this approach, one can hope to develop NbN HEB receivers which will operate in alternative,less costly, coolers (between 6-10K). The second approach focuses on minimizing the receiver noise temperature and maximizing the IF bandwidth, while operating a 4K. We have developed a film deposition process utilizing our DC reactive magnetron sputtering chamber. The films are deposited on MgO substrates which are heated to about 800'C during deposition. A typical Tc is about 10-11K and the transition width is very small (0.5K). The films are then evaluated by measuring their superconducting characteristics as well as their thickness and surface roughness using AFM analysis. PHEB devices are fabricated on the films in order to study their performances at THzHEB mixers. The device fabrication process performed at both NIST and UMass/Amherst involves lift-off lithography of the antenna (gold), and reactive ion etching (RIE) or wet etching of the NbN. Receiver noise temperatures and receiver noise bandwidths are then measured at UMass/Amherst with a laser LO which allows testing at a number of different frequencies. The latest results are described and discussed in this paper. A new antenna design and a new generation of MMIC amplifier to be incorporated with HEBs are also described.

Conference Dates

April 22-24, 2003

Conference Location

Tucson, AZ, USA

Conference Title

14th International Symposium on Space Terahertz Technoloyg

Pub Type

Conferences

Citation

Gerecht, E. , Bhupathiraju, V. , Nicholson, J. , Gu, D. , Zhuang, Y. , Morales, F. , Zhao, X. , Zannoni, R. and Yngvesson, S. (2021), Development of NbN THz HEB Mixer Devices and Films, 14th International Symposium on Space Terahertz Technoloyg, Tucson, AZ, USA (Accessed April 26, 2024)