All-NbN single flux quantum circuits based on NbN/AlN/NbN tunnel junctions

Authors
Citation
H. Terai et Z. Wang, All-NbN single flux quantum circuits based on NbN/AlN/NbN tunnel junctions, IEICE TR EL, E83C(1), 2000, pp. 69-74
Citations number
12
Categorie Soggetti
Eletrical & Eletronics Engineeing
Journal title
IEICE TRANSACTIONS ON ELECTRONICS
ISSN journal
09168524 → ACNP
Volume
E83C
Issue
1
Year of publication
2000
Pages
69 - 74
Database
ISI
SICI code
0916-8524(200001)E83C:1<69:ASFQCB>2.0.ZU;2-W
Abstract
We report on the fabrication and operation of all-NbN single Aux quantum (S FQ) circuits with resistively shunted NbN/AlN/NbN tunnel junctions fabricat ed on silicon substrates. The critical current varied by about +/-5% in 400 NbN/AlN/NbN junction arrays, where the junction area was 8x8 mu m(2). Crit ical current densities of the NbN/AlN/NbN tunnel junctions showed exponenti al dependence on the deposition time of the AlN barrier. By using the 12-nm -thick Cu film as shunted resistors, non-hysteretic current-voltage charact eristics were achieved. From dc-SQUID measurements, the sheet inductance of our NbN stripline was estimated to be around 1.2 pH at 4.2 K. We designed and fabricated circuits consisting of dc/SFQ converters, Josephson transmis sion lines, and T flip-flop-based SFQ/dc converters. The circuits demonstra ted correct operation with a bias margin of more than +/-15% at 4.2 K.