Low Capacitance Josephson Junctions
Original Publication Date: 1980-Oct-01
Included in the Prior Art Database: 2005-Feb-14
Superconducting tunnel junctions of reduced junction capacitance can be prepared by backscattering aluminum oxide onto the base electrode surface concurrently with cleaning it prior to tunnel barrier formation. For example, good quality/low capacitance junctions have been prepared using Nb base electrodes as follows: The base electrode is deposited in an appropriate manner. The samples are mounted on an RF cathode that is precoated with oxidized aluminum. The samples are sputtered in an Ar RF plasma at a peak-to-peak RF voltage of ~2 KV for times >/- 1/2 hour which cleans the sample surface and concurrently backscatters aluminum oxide onto the sample surface. The base electrodes are then oxidized to form the tunnel barrier, and a Pb or Pb alloy counterelectrode is deposited to complete the junction structure.