Device applications of self-assembled monolayers and monolayer-protected nanoclusters

The present status of self-assembled monolayers (SAMs) on different surfaces (2D systems) as well as monolayer formation on metallic and semiconducting cluster surfaces (3D SAM) to form monolayer-protected nanoclusters (MPCs) and their assemblies is reviewed briefly. Attention is focused mainly on the potential electronic and photonic applications of SAMs, MPCs and their 2D and 3D structures fabricated using covalent and hydrophobic interactions in contrast to the usual electrostatic assemblies. These examples illustrate the rational use of organic molecules and nanoclusters using the concept of self-assembly, where subtle systems of double tunnel junctions, hetero junctions and single-electron transition devices could be developed based on the structure and chemistry of multifunctional molecules. The tailoring of cluster size and cluster–cluster spacing to reveal interesting transitions in electronic properties is also demonstrated using the low temperature behavior of the 3D network of nanoclusters as an example. These devices are believed to play an important role in the coming years as the chip functions and clock frequencies reach orders of magnitude beyond those extrapolated from Moore’s law.