Investigation of the thermal stability of 2-D patterns of Au nanoparticles

Nanoparticles can serve as useful components or sub-assemblies, i.e., building blocks, in the design and fabrication of more complex structures needed for rapid prototyping using layered nanofabrication (LNF) or for use in nanoelectromechanical systems (NEMS). This paper describes investigations of the thermal stability of simple 2-D patterns of thiol-coated, 5-nm gold nanoparticles deposited on the native oxide surface of a Si(100) single crystal substrate. The changes in the particle structure and location on the surface were probed by using atomic force microscopy (AFM) before and after heating in ambient air. Experiments were carried out on the as-deposited nanoparticles and on patterns of nanoparticles that had been pretreated (prior to heating) by a 10-min exposure in a UV-ozone ashing chamber. All individual particles and 2-D patterns were stable up to 550 degrees C. Higher temperatures caused first a reduction in particle height and eventually a loss of the particle from the field of view (presumably by rather long-range diffusion).