Large capacity and high-speed random access memory devices using spin polarized electron tunneling current

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In this research, the Si/Ni-Fe composite underlayers were examined in order to improve the crystallinity and exchange bias characteristics of a reverse type of exchange coupled layers. Si underlayer promoted the formation of (111) texture of fcc crystallites in the Ni-Fe layer deposited on it. FeMn layer deposited on the Si/Ni-Fe bilayered underlayer revealed excellent (111) texture of fcc crystallites. The multilayered film with Si underlayer exhibited large exchange coupling field HィイD2ex.ィエD2 to the Ni-Fe films deposited on it after post-annealing process. It was found that HィイD2ex.1ィエD2 of the film with 50AィイD4oィエD4-thick Si underlayer took large value of about 300 Oe. Si/Ni-Fe composite underlayer improved crystallinity and (111) texture of the FeMn layer deposited on it, and sufficiently high HィイD2ex.ィエD2 could be applied to the upper Ni-Fe layer in a reverse type of exchange coupled layers by post-annealing in magnetic field.Co(15AィイD4oィエD4)/Cu(23AィイD4oィエD4) GMR (Giant Magneto-resistance) multilayers deposited on a-Si underlayer revealed exceedingly good crystallinity and on Ni-Fe underlayer revealed good periodicity and cleaness of interface. Annealing process varied these characteristic each other, and MR characteristics were changed on concerned with crystallographic characteristics. In the multilayers with Si underlayer, annealing at 250C improve the periodicity and the clearness at the interface, and the value of MR ratio was enhanced till 17.1%. Tunneling current characteristics were also observed in Ni-Fe/SiN/NiFe trilayered structure deposited on an a-Si underlayer.