Growth kinetics of nickel microstructures produced by laser-induced decomposition of nickel tetracarbonyl

Abstract

Nickel dots and films were deposited on Si-coated quartz plates by the cw Ar+ laser-induced decomposition of Ni(CO)4 at a temperature in the range of 200–400 °C. The deposited material was characterized by x-ray diffraction, Auger spectroscopy, nuclear reaction analyses, and scanning electron microscopy. The deposition kinetics of Ni dots formed in the laser-heated area of 200 μm in diameter was investigated as a function of irradiation time, output laser power, and Ni(CO)4 pressure. The laser-induced deposition of Ni dots was demonstrated to occur via a purely pyrolytic decomposition of Ni(CO)4. At low Ni(CO)4 pressures (typically below 0.3 Torr) and high output laser powers (above 1 W), the deposition rate of flat-topped Ni dots was found to be independent of the deposition temperature and proportional to Ni(CO)4 pressure. The deposition kinetics of these dots was limited by the number of molecules colliding with the heated area. At reactant pressures ranging from 0.3 to 10 Torr, the deposition rate of Gaussian Ni dots was found to be independent of Ni(CO)4 pressure, and the apparent activation energy was 11.6 kcal mol−1. The deposition kinetics of these Gaussian dots was controlled by the desorption of CO molecules.