Structural and Electrical Characterization of Three-Dimensional Superlattices of Organic Monolayer Protected Gold Nanocrystals

Micrometer-sized three-dimensional superlattices were fabricated by assembling Au nanocrystals modified with mercaptosuccinic acid in aqueous suspensions. Each superlattice formed a single crystal arrangement with a hexagonal close-packed structure where $a=5.1$ nm. The superlattices were densely deposited on a glass substrate and their electrical properties were investigated. The superlattice-assembled film showed ohmic behavior in the temperature range from 20 to 285 K. The absolute value of the resistivity was in the semiconductor region, but the resistivity slightly decreased as the temperature decreased. The temperature coefficient of the film was one order of magnitude smaller than that of bulk Au.