Large-area gold bicrystal film with a thickness of micrometers for break junction

Abstract This study demonstrates a unique method for fabricating microscale gold bicrystals by combining epitaxial growth and bonding techniques. Single crystal NaCl substrates with different orientations were bonded using AgCl, followed by deposition of gold films via high-temperature radio-frequency sputtering with high deposition rate under low vacuum. Wet-polished NaCl substrates allowed the formation of high-quality gold bicrystals by combining the orientations {100} Au ||{100} NaCl , {110} Au ||{110} NaCl , and {111} Au ||{111} NaCl . Electron microscopy confirmed the crystal structure and the isolated GBs. Electromigration tests used grain boundary (GB) diffusion to fabricate microscale break junctions in bicrystal gold films, demonstrating uniform break junctions along isolated GBs. This is in contrast to irregular break junctions in polycrystalline films. The results suggest that specific deposition conditions—high rate, low vacuum, and moisture exposure— are key to achieving high quality bicrystals, offering potential for precise break junction device applications.