High-fidelity transfer of epitaxial-grade crystalline Au microstructures for optoelectronic applications.

Abstract

Metal microstructures are fundamental components in electronic and optoelectronic devices. However, traditional energetic ion bombardment deposition techniques often introduce interface defects, strain, disorder, diffusion, and thermal or chemical incompatibility-particularly when integrating metals with two-dimensional semiconductors or unconventional substrates. Consequently, transfer printing techniques have emerged as alternatives. Nevertheless, existing methods typically rely on polycrystalline metals with inferior optoelectronic properties, leading to high optical losses and contact resistance. Here, we present a method for the large-area transfer of electrodeposited, atomically smooth epitaxial gold (Epi-Au) microstructures, including arrays, grids, and dendritic structure films. This approach leverages ultrapure water to induce spontaneous delamination of intact Epi-Au microstructures. Optical and electrical characterizations of the transferred architectures confirm the process reliability. Notably, the transferred 25-nm-thick Epi-Au grid on glass delivers an average electromagnetic interference shielding efficiency of 30.9 dB across the Ku-band (12-18 GHz)-rivalling metals hundreds of nanometers thick-confirming the transferred Epi-Au grids exhibit excellent electrical conductivity. Furthermore, a transferred 6-nm-thick monolithic Epi-Au dendritic structure on a flexible PDMS substrate maintains structural integrity without branch loss and exhibits 70%-80% transmittance across the 400-900 nm wavelength range. These results validate the high fidelity of our transfer method and demonstrate the significant potential of high-quality Epi-Au microstructures for advanced optoelectronic applications.