Co surface modification by bias sputtering in Cu/Co(V b )/NiO/Si(100) magnetic multilayer structures

Abstract

To investigate the Ta/Co/Cu/Co/NiO/Si(100) spin valve structure, fabrication and characterization of the Cu/Co/NiO/Si(100) system was studied for further understanding the structure. The system was grown by employing combinative DC sputtering-evaporation technique. Nickel oxide with a thickness of about 30 nm was deposited on Si(100) substrate using thermal evaporation technique.The cobalt film, then, with a thickness of about 3 nm was grown by DC sputtering under various applied negative bias voltages ranging from 0 to - 80 V. The optimum bias voltage (V b = -60 V) for the growth of Co layer was determined by atomic force microscopy (AFM), four-point probe sheet measurement (R s ) and scanning electron microscopy (SEM). Following the Co deposition at the optimum condition, the Cu layer with a thickness of about 2 nm was deposited on the Co(V b )/NiO/Si(100) structure by using DC magnetron sputtering technique. The Cu/Co(V b )/NiO/Si(100) structure was examined by AFM and R s measurements. Our data analysis indicates that Cu possess a proper surface for the growth of next Co layer in the Co/Cu/Co active GMR region.