Material synthesis by the transformation of organometallic compounds (precursors) by vapor deposition techniques such as chemical vapor deposition (CVD) and atomic layer deposition (ALD) has been in the forefront of modern day research and development of new materials. There exists a need for new routes for designing and synthesizing new precursors as well as the application of established molecular precursors to derive tuneable materials for technological demands. With regard to the precursor chemistry, a most detailed understanding of the mechanistic complexity of materials formation from molecular precursors is very important for further development of new processes and advanced materials. To emphasize and stimulate research in these areas, this volume comprises a selection of case studies covering various key-aspects of the interplay of precursor chemistry with the process conditions of materials formation, particularly looking at the similarities and differences of CVD, ALD and nanoparticle synthesis, e.g. colloid chemistry, involving tailored molecular precursors.

Cyclic molecular systems of the type, A(XX')B(YY')n (where A, B = Al, N or Si, C; X, X', Y, Y'= 11, CH3, etc. and n 2 and 3), were studied as potential single-source precursors for the CVD of AlN and SiC films. These compounds provide the required elements for die product film already covalently bound to one another in a single, volatile molecular source and, in the case of the SiC precursors (where n = 2), they contain built-in ring-strain energy to lower the decomposition onset temperature. Efforts have included the study of the (CH3)2AlNH23 --> AIN CVD system by mass-spectrometric/time-of-flight measurements and the investigation of substituted disilacyclobutanes as single- source SiC precursors. The mass-spec/-TOF studies have indicated that a slow decomposition of the (CH3)2AlNH23 (I) precursor to produce methane and a series of higher oligomeric products occurs during its vaporization at 75-100 deg C. These oligomeric species are believed to be intermediates formed in the gas- phase thermal decomposition of I to AlN. This precursor was used to deposit high quality AlN films up to 2 micrometers thick on Si and sapphire substrates in a LPCVD apparatus and is being tested for use in the deposition of AlN interface layers in A1203-reinforced metal matrix composites. Disilacyclobutane, SiH2CH22, was found to yield stoichiometric, crack-free, adherent, polycrystalline SiC films on Si (100) and Si (111) surfaces by LPCVD at temperatures as low as 690 OC. Chemical vapor deposition (CVD), AIN, SiC, Organometallic precursor.

The importance of platinum group metals for catalytic and microelectronic applications has prompted research into the development of novel molecular precursors for chemical vapor deposition of thin films of these metals. A variety of molecular architectures, ligand systems, as well as deposition conditions are investigated and related to the morphology and composition of the resultant films. For example, amorphous thin films of ruthenium and phosphorus alloys are deposited using single source metal hydride precursors, while use of the 3,5-di-substituted pyrazolate ligand in conjunction with various rhodium starting materials leads to a variety of different volatile monomeric and dimeric complexes. Synthesis of pyrazole and pyrazolate complexes of tungsten and palladium are also explored. In a related research area, progress towards the development of novel synthetic routes to mesostructured transition metal phosphides and borates for Li-ion battery electrode applications is summarized. Traditional routes to these materials involve high-temperature syntheses, allowing limited control over morphology. Identification of low-temperature reaction conditions necessary to afford a desired composition, morphology and electrochemical performance of the bulk material are the main goals of this project, and results are discussed with various early transition metals.