ISSTT Proceedings

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Superconducting contacts and NbN HEB mixer performance

Authors:
Tarun Aggarwal, Pourya Khosropanah, Wen Zhang, Frans D. Tichelaar, Jian-Rong Gao, T.M. Klapwijk
Abstract:
We demonstrate that the performance of phonon cooled NbN hot electron bolometer mixers depends on the superconducting interlayer between the NbN bridge and the Au antenna. This interlayer is either a superconducting Nb layer or a NbTiN layer. We find that, for given interface cleaning conditions, the mixers with a Nb interlayer show a similar or even a slightly better noise temperature in comparison with the mixers with a NbTiN interlayer. The best receiver noise temperature is 1230 K at 2.5 THz and becomes 980 K corrected for reflection loss due to the use of a Si lens. An important outcome of this study is that the Nb interlayer can lead to excellent performance of HEB mixers. Unlike NbTiN, a Nb sputtering process is widely available and easy to use. In addition, we also inspect the interfaces of the contact structures using HRTEM and find that the interfaces of NbN/Nb and NbN/NbTiN after Ar+ cleaning are excellent.
Categories:
HEB Mixers, Poster Session
Year:
2008
Session:
P2
Full-text:
Download a PDF of this paper.
Page Number(s):
398-402