The effects of deposition conditions on microstructure and morphology of r.f.-magnetron sputtered GdTbFeCo thin films

Abstract

GdTbFeCo alloy thin films were r.f.-magnetron sputtered onto glass substrates and onto carbon-coated 3 mm diameter copper grids for transmission electron microscope observations at different argon pressures P Ar and incident r.f. powers. The mosaic target was assembled by bonding pure metal Gd, Tb and Co chips to a 100 mm diameter pure Fe disc. X-ray and selected area electron diffraction analyses indicate that the deposited GdTbFeCo films are all amorphous and very uniform in both thickness and composition. Transmission electron microscope observations show that as the r.f. power is maintained at 500 W the films deposited at low and moderate pressures ( P Ar ⩽ 1 Pa ) exhibit a smooth and featureless microstructure, while the films deposited at high P Ar (greater than 2 Pa) exhibit a rougher appearance and honeycomb-like network structure surrounded by microvoids. However, the microstructure of films deposited at powers of 200, 500 and 600 W and at a constant P Ar of 2 Pa do not reveal any significant difference except that there is a slight increase in surface roughness with increasing power. These results suggest that the deposition conditions, especially argon pressure, strongly affect the morphology and microstructure and in turn, the stability, magnetic and magneto-optical properties of GdTbFeCo thin films.