An investigation of the thermal cycling stability of Bi2Sr2CaCu2Ox stacks fabricated by self-planarizing process

摘要

We have investigated the thermal cycling properties of Bi2Sr2CaCu2O chi, (Bi-2212) stacks since the thermal stability is one of the most important factors in determining successful applications of the Josephson effect. The stacks with an area of 30 x 40 cm(2) or 15 x 40 cm(2) were fabricated by self-planarizing process. The surfaces of the device with or without a 100 nm-thick overlying SiO2 layer were coated by AZ-5206E photoresist to protect from water vapor in the air. The current-voltage (I-V) characteristics of the stacks exhibited large hysteresis and multiple branches, which can be explained by a series connection of highly capacitive Josephson junctions. The observed critical currents (I-c) for the surface junctions in the stacks did not change with thermal cycling up to 150 cycles repeated between 77 and 300 K. This suggests that the self-planarized Bi-2212 stacks have sufficient stability for thermal cycling. (C) 2007 Elsevier B.V. All rights reserved.