Program and Abstract Book - SRON
Program and Abstract Book - SRON
Program and Abstract Book - SRON
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19 th International Symposium on Space Terahertz Technology<br />
0.85-THz SIS Mixers with Vertically Stacked Junctions<br />
P3-6<br />
Ming-Jye Wang 1 , Tse-Jun Chen 1 , Chuang-Ping Chiu 1 , Hsian-Hong Chang 2 , Jing Li 3,4 , <strong>and</strong><br />
Sheng-Cai Shi 3<br />
1. Institute of Astronomy <strong>and</strong> Astrophysics, Academia Sinica, Taipei, Taiwan<br />
2. Department of Physics, National Tsing-Hua University, Hsin-Chu, Taiwan<br />
3. Purple Mountain Observatory, NAOC, CAS, China<br />
4. Graduate School of Chinese Academy of Science, CAS, China<br />
Vertically stacked SIS junctions (VSJ), with individual junctions connected in series but without<br />
introducing any additional connection wires, has been demonstrated to be used as a mixer at frequency of<br />
100GHz [1]. VSJ has a simple structure <strong>and</strong> an equivalent normal-state resistance of relatively large value,<br />
which may make impedance matching easier in mixer application. In addition, the dynamic range of VSJ<br />
mixer can improved by factor of N 2 [2, 3], where N is the number of stacked SIS junctions. Recently, the<br />
coherent THz source has been demonstrated in high temperature superconductor which has intrinsic<br />
stacked Josephson junctions [4]. It is interesting if the coherent IF can be detected in a VSJ mixer.<br />
We propose to develop a 0.85-THz superconducting SIS mixer with two vertically stacked<br />
Nb/AlOx/Nb junctions incorporating with two types of integrated tuning circuits, i.e., tuning inductance in<br />
series (end loaded) <strong>and</strong> shunted inductance followed with a quarter-wavelength open stub. Notice that the<br />
former still needs a section of impedance transformer, <strong>and</strong> the latter can be directly connected to the<br />
mixer-mount’s feed point. The designed junction critical current density <strong>and</strong> junction area are equal to<br />
7kA/cm 2 <strong>and</strong> 1μm 2 , respectively. Numerical simulations demonstrate that the shunted-inductance design<br />
has a superior performance in both noise temperature <strong>and</strong> b<strong>and</strong>width. Nb/Al-AlOx/Nb/Al-AlOx/Nb<br />
multilayer is deposited in as single vacuum process by st<strong>and</strong>ard Nb-technology. The VSJ is defined by<br />
etching the top three layers (Nb/Al-AlOx/Nb) using ICP-RIE system. The thickness of middle Nb can be<br />
varied to study the coherent IF generation in a VSJ mixer. Detailed simulation results <strong>and</strong> preliminary<br />
experimental results will be presented.<br />
[1] V. Yu. Belitsky, S.W. Jacobsson, S. A> Kovtonjuk, E.L. Kollberg, <strong>and</strong> An. B. Ermakov, International<br />
Journal of Infrared <strong>and</strong> Millimeter waves, 14, 5, pp.949-957, 1993<br />
[2] S. Rudner, M.J. Feldman, E. Kollverg, <strong>and</strong> T. Claeson, Journal of Applied Physics, 52, 10, pp.6366-<br />
6376, 1981<br />
[3] D.G. Grete, W.R. McGrath, P.L. Richards, <strong>and</strong> F.L. Lloyd, IEEE transaction on MTT, MTT-35, 4,<br />
pp.435-440, 1987<br />
[4] L. Ozyuzer, A. E. Koshelev, C. Kurter, N. Gopalsami, Q. Li, M. Tachiki, K. Kadowaki, T. Yamamoto,<br />
H. Minami, H. Yamaguchi, T. Tachiki, K. E. Gray, W.-K. Kwok, <strong>and</strong> U. Welp, SCIENCE, 318, pp.1291-<br />
1293, 2007<br />
122
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