LASER PHOTOCHEMISTRY AT SURFACES - LASER-INDUCED CHEMICAL VAPOR-DEPOSITION AND RELATED PHENOMENA

Laser chemistry finds application in thin film deposition, in the formation of surface layers, as well as in (structuring) ablation or etching, and in the initial and enforcing of reactions at surfaces. In the present paper an introduction to these new possibilities on the general basis of molecule-surface interactions is followed by a brief characterization of lasers suitable for such purposes. Thereafter, four examples are discussed: gas phase deposition from volatile organometallic compounds with photoelectric activation at the surface or photochemical activation of the gaseous species (i.e., by employing molecular beams). In this way, (noble) metal contacts can be deposited on various substrates. Instead of surface deposition, nucleation can occur in the gaseous medium, yielding highly disperse powders, e.g., of silicon carbide. Finally, an etching reaction is discussed where the laser does not act as an energy source but as an analytical instrument to provide diagnostic and mechanistic information.