D.M. Jeon

The distribution of Cu and resultant resistivity change in sputter deposited Al–Cu film as a conductive layer

Abstract As a conductive layer, sputter-deposited Al–Cu 1 at.% thin film was investigated, with particular focus on the effect of Cu precipitates and film strain on the electric conductivity. The 400-nm-thick film was deposited on Si wafer and heat-treated at 200 and 480 °C. Cu precipitation was investigated using electron microscopy and film strain using XRD. As a result of heat treatment, changes in the electric resistivity showed the same trend as the film strain. This study concluded that the trends in resistivity and film stress could be related to Cu precipitation to some extent. In other words, the resistivity changes depending on whether the precipitates are coherent with the Al matrix and on the distribution of the precipitates.

Plasma oxidation and magnetoresistance in tunnel junction device

Abstract We have studied the tunneling junction magnetoresistance (TMR) and oxidation behavior of Al layer in glass\Co 100 A\Al–O x ( t A)\Co 30 A\Ni–Fe 120 A tunnel junction devices. The Al–O x thickness was controlled with a different oxidation time and Al thickness. The thin Al layer of 15 A showed a rapid variation of TMR ratio with a oxidation time and the maximum TMR ratio of x layer by a high resolution transmission electron microscopy. As an oxidation time increase, the initial Al film with some roughness became flat, which was consistent to a variation of a junction resistance. From results, the rough Al layer could be grown to a flat Al–O x in an optimum oxidation condition, which was based on the oxidation kinetics of Al.

Dependence of exchange bias on various annealing conditions in Mn-Ir-Pt based spin valves

In this paper, we have investigated the annealing conditions for a Mn-Ir-Pt based top and bottom conventional SVs and have evaluated the blocking temperature and the thermal stability of H/sub ex/ at the ramped temperature. The change of an interface was confirmed from a RBS study.

Effect of surface roughness on plasma oxidation behavior of Al layer and tunneling magnetoresistance

In this paper, we evaluated the variation of magnetic properties and junction resistance R/sub j/. And the oxidation behavior was analyzed by a high resolution transmission microscopy (HR-TEM) study.

The effect of controlled P1 and P2 in synthetic spin valve with Mn–Ir–Pt exchange biasing layer

Abstract Synthetic top and bottom spin valves including the Mn–Ir–Pt/Co–Fe (P1)/Ru/Co—Fe (P2) synthetic pinned layer were prepared by controlling the thickness difference (Δ t =P1–P2) of Co–Fe layers. The effective exchange field ( H eff,ex ) and giant magnetoresistance (GMR) properties of both synthetic type SVs were investigated as a function of Δ t . The H eff,ex was dependent largely on the Δ t . The GMR properties are strongly dependent on the stacking sequence of synthetic SVs and Δ t . Based on the magnetic and electrical properties at room temperature, the thermal stability of synthetic SVs was also evaluated at various elevated temperatures in both types of SVs.

The Effect of the Interface Impurity in Fabrication of Spin Dependent Tunnel Junction

Ferromagnetic-insulator-ferromagnetic tunneling was measured in two types of Co/Al2O3/Co/NiFe junctions. For type 1 junction (two times of interface exposure to air), the maximum tunnel junction magnetoresistance (TMR) ratio was 16.5% at room temperature. Junctions with a relatively thicker Al layer showed a lower resistance and a higher TMR ratio. Whereas, junctions with a relatively thinner Al layer showed a fast increase of barrier width. The passivation effect of Al2O3 in oxidation process enhanced the TMR ratio. As the oxidation time is increased, the coercivity of Co bottom electrode is also increased. So the effect of CoO formation in the interface of the Co bottom electrode and the Al2O3 is discussed in three possible assumptions. For type 2 junction (just one time of interface exposure to air), the maximum TMR ratio was 21% at room temperature. And the TMR ratio was decreased to half at 550 mV. These junctions have potential use as low-power field sensors and memory elements.