Ultra-thin gold films: towards 2D metals for photonic and optoelectronic applications

V S Volkov,K V Voronin,A V Arsenin,R V Kirtaev,M S Mironov,G A Ermolaev,Y V Stebunov,S M Novikov,D I Yakubovsky

doi:10.1088/1742-6596/1461/1/012184

Abstract

Fabrication of continuous ultra-thin (<10 nm) and ultra-smooth gold films on different substrates is reported. Using a variety of electrical, optical and structural characterization techniques, we show that monolayer MoS2 can be superior to more conventional adhesion/seeding layers as an optical substrate for realizing ultra-thin gold films. Our results show that optical losses in ultrathin gold films increase with decreasing thickness due to the fine-grained structure and the presence of a small number of voids, however, they exhibit metallic properties down to a thickness of 3-4 nm.

Highlights

Gold is a important material for many applications in optics, electronics, photonics, plasmonics, and biosensing as it possesses a number of favorable electrical, optical, physical and chemical properties [1,2]
Using a variety of electrical, optical and structural characterization techniques, we show that monolayer MoS2 can be superior to more conventional adhesion/seeding layers as an optical substrate for realizing ultra-thin gold films
Our results show that optical losses in ultrathin gold films increase with decreasing thickness due to the fine-grained structure and the presence of a small number of voids, they exhibit metallic properties down to a thickness of 3-4 nm

Summary

Introduction

Gold is a important material for many applications in optics, electronics, photonics, plasmonics, and biosensing as it possesses a number of favorable electrical, optical, physical and chemical properties [1,2] It is well-known that the growth of continuous and ultrathin gold films on different substrates, such as glass, silicon oxide, silicon nitride, graphene etc., is notoriously difficult due to the poor wetting of gold to these materials [3,4,5]. To reduce the percolation threshold of ultrathin gold films, adhesion or seed layers of Ti, Cr, Ni, Pt or Ge are commonly used These adhesion layers significantly affect the optical and electrical properties of ultra-thin metal nanostructures [6, 7]. We have undertaken numerous experiments with different deposition regimes (to study the change in the optical and electrical properties of ultra-thin gold films with respect to differences in structural features) and focused on observing how the different under-layers affect the growth kinetics and characteristics of continuous ultra-thin gold films

Materials and methods

Results and discussion

Conclusions