Kinetics of laser-induced chemical vapor deposition of gold

Rates of photothermal gold deposition onto alumina substrates heated by a focused argon-ion laser beam were measured by determining the time required for deposits to grow through the focal spot of a HeNe laser probe beam directed parallel to the substrate. Deposition rates from 0.25 to 6 μm/s were measured for deposits with heights ranging from 5 to 100 μm. Rates of gold deposition using dimethyl gold hexafluoroacetylacetonate as a precursor depend linearly on the gold precursor partial pressure and for a wide variety of conditions do not depend on the laser power or focal spot diameter. A theory is presented to describe reactant mass transfer-controlled deposition with and without buffer gas. Comparison of measured with calculated growth rates showed that gold deposition rates using dimethyl gold hexafluoroacetylacetonate as a precursor were transport limited for the conditions studied. Theory and experiment also showed that the deposition rate decreases inversely with increasing buffer gas pressure above a critical pressure.