Nov 22, 2012
Antimony sublimation enhances noble metal nanostructure assembly
Ultrathin metal films when heated tend to agglomerate into nanoscale droplets. This process, referred to as thermal dewetting, is the most straightforward means of fabricating substrate-supported noble metal nanostructures. It is, however, quite inflexible and typically yields either densely packed smaller structures or widely spaced larger structures. Now, scientists in the US have enhanced the process by introducing a sacrificial antimony layer between the substrate and noble metal overlayer.
The team of researchers from the College of Engineering at Temple University used readily available instrumentation, consisting of a thin-film sputter coater and tube furnace, to deposit ultrathin films of silver or gold on sacrificial antimony layers. By merely varying the thickness of the antimony layer between 0 and 40 nm, they were able to manipulate the nanostructure density derived from the same gold film thickness by four orders of magnitude.
Substrate-supported gold nanoparticles
Using the modified technique, the gold layer thickness determines the quantity of gold to be agglomerated, while the antimony layer thickness dictates the characteristic length scale over which the agglomeration occurs. The result is a far more flexible process than conventional thermal dewetting and allows the nanoparticle size and areal density to be tailored to a greater degree to meet the needs of a specific application.
Substrate-supported noble metal nanostructures are of importance in numerous areas such as photovoltaics, catalysis, chemical and biological sensing, the formation of nanowires via the vapour-liquid-solid growth mode and as shadow masks for reactive ion etching.
The researchers presented their results in the journal Nanotechnology.
About the author
The study was conducted by researchers from the Renewable Energy Laboratory in the College of Engineering at Temple University, US. Pouyan Farzinpour, Aarthi Sundar and Kyle D Gilroy are PhD students, Zachary E Eskin is an undergraduate research intern, and Dr Robert A Hughes and Dr Svetlana Neretina are assistant professors.