Ultraviolet light assisted oxidation for magnetic tunnel junctions

Recently, ferromagnetic tunnel junctions attracted much interest because th ey exhibit large magnetoresistance effects up to Delta R/R=40% at room temp erature. In this paper, an alternative approach will be presented, i.e., ex posing the aluminum film to ultraviolet light during oxidation. The underly ing mechanism can be explained in the framework of the Cabrera-Mott theory of oxidation. With UV assisted oxidation, magnetoresistance ratios of up to 22.5% at room temperature have been obtained in Ni80Fe20-Al(ox)-Co junctio ns. The resistivities were in the 1 k Omega mu m(2) range for junctions of 25-400 mu m(2). Barrier heights obtained by fitting to different theories w ill be discussed. (C) 2000 American Institute of Physics. [S0021-8979(00)55 308-0].