Josephson device fabrication method

Abstract

Abstract A method for changing Josephson device parameters, e.g., the critical current of a Josephson junction. The method comprises incorporating doping material into the device, or part of the device, followed by a light anneal. Exemplary dopants include In, Sn, Sb, Te, Bi, Hg, Mg, Li, Cd, Na and Ta, with In, Sn, and Sb being preferred dopants for changing the critical current of a Josephson junction having a Pb-containing counter electrode. The dopant can be incorporated into the device by in-diffusion after deposition onto the surface, by ion implantation, or by any other convenient method. The amount of dopant required is typically small. For example, deposition of a Sn layer of 0.05 nm effective thickness onto the 200 nm thick Pb-Sb(1.5 wt. %) counter electrode of a cross-type Josephson junction, and annealing at 80 DEG C. for about 3 hours, resulted in an increase in the critical current of the junction by a factor of about 2.5. The method is considered to have wide applicability in the manufacture of Josephson devices, and can be applied globally, i.e., to all the devices on a wafer or chip, or locally, i.e., to selected devices.

Inventors

• 👤 Theodore A. Fulton
• 👤 Shin-Shem Pei

Bibliographic Details