| The formation of structures with molecular scale organization on surfaces is important for technology development in areas such as microelectronics, optical materials, coatings and biomaterials. The use of alkyl chain molecular assemblies and ultrathin polymer films on solid surfaces represents a step in this direction. Understanding of the chemical issues involved is necessary for controlled engineering and application of these structures. The fabrication and characterization of all these structures involves the application of diverse tools and analytical strategies. Combination of surface sensitive techniques and optical methods such as ellipsometry and infrared spectroscopy, together with quantitative methods of interpretation of the spectra was used in the determination of molecular organization. A new class of ultra-thin polymeric films was developed by the polymerization of diazomethane on gold surfaces. These films are robust and form crystalline, low-dielectric conformal structures on the substrate. Film formation was found to originate by cluster formation at high-energy sites on the gold surface, such as grain boundaries and defect sites. The clusters grow parallel and perpendicular to the surface, and at a certain point, growth spills over to the terraces. These form "nanowell" like structures that have been characterized by electrochemical measurements. These have been used to fabricate novel chemical structures on gold surfaces Self-assembled monolayer films formed from octadecyltrichlorosilane have been used as high-resolution resists for electron beam lithography. The parameters involved in the formation of the siloxy-backbone and the organization of the pendant alkyl chains were investigated using parallel studies on poly(n-alkylsiloxane), The chemistry of the electron beam irradiation has been exhaustively investigated. This has both allowed for, and necessitated the development of protocols for film formation, pattern transfer and surface modification. The case of polymethylene on gold and that of pattern formation using self-assembled monolayers represent two extremes in chemical control in the formation of nanoscale structures on surfaces. The first case is an example of substrate controlled structure formation, and the second exemplifies external control of structure formation on surfaces. |
