Modeling and Simulation of Tunneling Current in Oxygen-Plasma-Treated Aluminum Oxide Insulating Barrier for Magnetic Tunnel Junction

Authors present a current conducting model of tunneling current on O plasma treated AlOx for conventional in-plane magnetized magnetic tunnel junctions (I-MTJs) Al (25 nm)/Co (25 nm)/AlOx (1.8 nm)/Ni80Fe20 (30 nm)/ AlCu (30 nm)/SiO2 (1 mu m)/Si and perpendicularly magnetized MTJs (P-MTJ) Al (25 nm)/Cu (2 nm)/Tb21Fe79 (30 nm)/AlOx (2.2 nm)/Gd21Fe79 (50 nm)/AlCu (25 nm)/SiO2 (1 mu m)/Si. The current conducting model includes direct tunneling current in consideration of image force and "hopping" conducting current through traps in AlOx, and the model is able to explain the I-V characteristics of Pd (250 nm)/AlOx (1.8 nm)/Ni80Fe20 (30 nm)/AlCu (30 nm)/SiO2 (1 mu m)/Si and Pd (250 nm)/AlOx (2.2 nm)/Gd21Fe79 (50 nm)/AlCu (25 nm)/SiO2 (1 mu m)/Si samples, which depend on O plasma treatment conditions. Regarding suitable O plasma treated AlOx film, its I-V characteristics fit well direct tunneling model that includes image force, therefore, the I-MTJ using the thin AlOx achieves a 13.8% magnetoresistive ratio. 10 refs.