Ion beam deposition and oxidation of spin-dependent tunnel junctions

Spin dependent tunnel junctions showing tunnel magnetoresistance (TMR) values of 39 similar to 41 % were fabricated using Ion Beam Deposition (IBD), Both the electrodes and the aluminum layer deposition were done by IBD. The aluminum oxidation was performed using the assist gun with an oxygen beam (+30 V acceleration voltage applied on the grids) using mixed O-2/Ar plasma, The oxidation was monitored in real time with a residual gas analyzer (RGA), The junction area is defined by lithography, down to 3x2 mu m(2). As deposited junctions with 15 Angstrom of Al showed TMR of 27 similar to 29 %, independent of the junction area. with resistance-area products of 0.8 similar to 1.6 M Omega x mu m(2). This TMR value reached 40 % upon annealing at 290 degrees C, with resistance decreasing to 0.5 similar to 0.8 M Omega x mu m(2).