Fabrication of transferable ultrathin Au films with eminent thermal stability via a nanocrystalline MoS2 interlayer

Abstract

Ultrathin gold (Au) films are a critical component in plasmonics, metal optics, and nano-electronics devices. However, fabricating ultrathin Au films faces a great challenge due to the dewetting behavior of Au when being deposited onto an oxide (such as SiO₂/Si or Al₂O₃) substrate. This problem is often relieved by introducing a metal or an organic adhesion layer to bind the Au film with the substrate. While the interdiffusion and thermal instability of the adhesion layers often negatively affect the physical properties of the films. Besides, this kind of Au film is usually untransferable due to the strong chemical bonding at the interfaces. Herein, we demonstrate a new strategy of utilizing a nanocrystalline MoS₂ layer as the adhesion interlayer to stabilize the Au film. The atomically thin nanocrystalline MoS₂ with abundant fresh edges enhances the wetting of Au films and allows for the ultra-smoothness and a few nanometers in thickness of the Au films without interdiffusion. The resulting ultrathin Au films possess superior electrical conductivity, high optical transmittance, and eminent thermal stability, which are much better than those utilizing Cu or Ti as the adhesion layers. Moreover, these Au films can be easily transferred to arbitrary substrates. Our method provides a new benchmark in the fabrication of transferable ultrathin and thermally stable Au films.