Laser-induced Oxide Research Articles

Localization of electrode reactions by a focused laser beam

The localization of electrode reactions in a focused laser beam is compared to other localization techniques such as photolithography or the application of catalysis and inhibition. The geometric resolution of the reactions is given by primary effects of the laser spot and secondary effects of the system (light scattering, thermal and electronic conductivity). A combination of several localization methods is favourable. Tests with natural (Ti) and artificially simulated (Ti/TiN) grain boundaries show a resolution of some µm close to the theoretical resolution, as long as low power densities are used. Some progress has been achieved by full coordination of observation with localized laser radiation. Most of the localized reactions studied are based on photoelectrochemical processes at thin n-type semiconducting films, but localized photochemical copper deposition onto quartz is also presented. Quantitative investigations are carried out with laser-induced Ag-deposition onto anodic TiO2 layers as an example. Experiments with point arrays as well as velodynamic experiments prove that optically visible spots can be obtained after a minimum consumption of some 1017 e cm–2. With increasing power density the reaction becomes delocalized by secondary effects. Depending on the illumination time, i.e. the number of photons absorbed, competition between laser-induced oxide growth and metal deposition was observed on Nb2O5 layers. Substrate influences are demonstrated by various examples. Long-range effects are caused by charge-carrier migration. Furthermore, crystallization is induced far away from the laser spot.

ChemInform Abstract: Structural Investigations and Microhardness of Metal Oxide Layer Grown by CO2 Laser Light.

AbstractCO2‐laser irradiation (30 W, 10‐60 s) of vanadium surfaces results in the formation of V2O5 films of 50‐300 μm thickness and good adhesion.

Infrared characterization of UV laser-induced silicon oxide films

Oxygen incorporation and subsequent oxidation of ion-implanted silicon have been performed using repetitive pulsed excimer laser irradiation working in the liquid phase regime. The kinetics of the oxidation and the characterization of the grown SiO2 were investigated by infrared spectroscopy. The origin of the broadening of the Si-O stretching band of these oxides grown from the liquid phase is discussed.

Structural investigations and microhardness of metal oxide layer grown by CO2 laser light

Abstract Laser-induced vanadium oxide formation is described. Structural and metallographic analysis indicated the existence of a mosaic-like vanadium pentoxide layer with good adhesion and a very large free surface. The microhardness of the produced oxide layer was found to be two to three times higher than the microhardness of monocrystals.