650-GHz and 1-THz Josephson Array Oscillators Using Shunted Tunnel Junctions with a Small Parasitic Inductance(Special Issue on Superconductive Electron Devices and Their Applications)

概要

論文の詳細を見る
Resonant properties of resistively shunted tunnel junctions dominate the high-frequency performance of Josephson array oscillators. To improve the operating frquency, we have developed resistively shunted Nb/AlO_x/Nb tunnel junctions with a small parasitic inductance. The inductance was minimized by reducing the inductive length between the tunnel junction and the contact hole to be about 1μm. By fitting the measured I-V characteristics of the shunted tunnel junction to the simulated characteristics, we estimated the inductance to be about 105fH. The analysis of resonant properties showed that the shunted tunnel junctions with the small parasitic inductance have a high-frequency performance up to the Nb gap frequency. Josephson array osillators using 11 such junctions were designed and fabricated to operate at 650GHz and 1THz. Shapiro steps induced by Josephson oscillation were clearly observed up to 1THz. By fitting the step heights to the simulated results, we estimated the output power of the Josephson oscillator delivered to the load resistor to be about 10μW at 625 GHz and 50nW at 1THz.
一般社団法人電子情報通信学会の論文
1998-10-25