Microstructure of cobalt and cobalt-phosphorous thin films

Abstract

The morphology and crystallography of Co and Co(P) thin films (<500 Å), produced by electroplating, were examined by electron microscopy and diffraction. It was found that the pH of the plating solution affects phase constitution and texture as it does in thicker films. Films deposited at low pH showed appreciable proportion of fcc grains, and the hexagonal grains were oriented with their axes of easy magnetization parallel to the film plane. At high pH, the deposits were hexagonal and showed 〈00.2〉 fiber axis. A pH of 3 to 4 corresponded to the transition region. Phosphorus was co-deposited with cobalt by adding hypophosphite ion to the plating solution. It acts as grain refiner, stabilizes the hexagonal phase, and randomizes the texture. An explanation of the effect of phosphorus on magnetic properties, which enables magneto-optic recording, is suggested.