Aminopropylsilatrane Linkers for Easy and Fast Fabrication of High-Quality 10 nm Thick Gold Films on SiO2 Substrates

Fabricating smooth and contamination-free sub-10 nm thick gold layers on dielectric substrates is of interest for a number of applications, including plasmonics, metamaterials, and nanoelectronics. Metallic adhesion layers are often used to facilitate good adhesion between gold and substrates, but at the cost of interfacial alloying and subsequent deterioration of the optical and electrical properties of the thin films. Another approach for promoting adhesion between gold and SiO2 substrates is the use of self-assembled organosilane monolayer linkers, such as (3-aminopropyl)trimethoxysilane (APTMS). APTMS, however, is a corrosive chemical, and its monolayer preparation is highly sensitive to ambient conditions. Here, we introduce an easy and fast immersion process using (3-aminopropyl)-silatrane (APS) for achieving smooth and high-purity gold films and compare its performance to APTMS. Our APS recipe is water based, does not require environmental considerations, and has approximately 6 times faster deposition time than APTMS (30 min vs 3 h). The results demonstrate that both organic molecules promote the formation of continuous and smooth 10 nm thick gold films, without leading to considerable chemical intermixing at the interface. Monitoring the growth evolution of the gold layer indicates a threshold thickness of 6-7 nm for obtaining continuous films. Overall, the ease of use, faster processing time and low toxicity of APS make it an attractive choice for fabricating high-quality ultrathin gold films on SiO2 substrates.