ECRプラズマ酸化により作製したNi_<80>Fe<20>/Co/Al-O/Co接合のTMR  [in Japanese] TMR Effect in Ni_<80>Fe_<20>/Co/Al-O/Co Junctions Prepared by Using ECR Plasma Oxidation  [in Japanese]

Ni_<80>Fe_<20>/Co/Al-O/Co tunnel junctions were fabricated by using magnetron sputtering and metal masks. The insulator was prepared by ECR oxidation of a thin metallic Al film. The dependence of the tunnel resistance and TMR ratio on the oxidizing condition was examined. The tunnel resistance increased and the TMR ratio decreased rapidly with increasing acceleration voltage and oxidizing time. The junction area dependence of the tunnel resistance and TMR ratio was analyzed by taking account of a current distribution effect. The values of the TMR ratio and tunnel resistance obtained by this analysis were about 13% and 1.2x10^5Ω・μm^2, respectively. The decrease in the TMR ratio can be explained by the oxidation of the surface of the lower Co layer.