Abstract
Electroless based Ni-Co-P alloy thin films were deposited using sodium hypophosphite as a reducing agent and sodium citrate as a complexing agent in an alkaline plating bath. The effect of solution pH and temperature on the plating rate was examined. The decrease in activation energy (81.35 - 73.54 kJ mole(-1)) for the Ni-Co-P thin films deposited on corning glass was observed with the increase in pH (8.5-9.38) of the plating bath. There is a significant decrease in sheet resistance of alloy thin films as the post deposition annealing temperature approaches 400 degrees C. The presence of nickel as well as nickel phosphide peaks and transition from metastable Ni12P5, Ni8P5 and Ni5P2 phases into thermodynamically stable NiP, NiP2, Ni3P phases after annealing at 600 degrees C was observed in XRD spectra, indicating the crystallization of the thin films. Surface topography analysis shows the variation of grain size in the range 20-40 nm.