Growth of Nickel Silicide/Platinum Silicide Axial Nanowire Heterostructure through Solid-State Reaction

Nickel monosilicide (NiSi) with the addition of platinum has been highly regarded as paramount candidate for excellent contact in semiconductor industry for its low electrical resistance and high thermal stability. With the transition of device dimension to nanoscale, 1-D NiSi nanostructures with excellent metallic contact to Si nanostructures have attracted much interests in the field of nanoelectronics. Therefore it is important to investigate the nickel silicide formation and transformation mechanism in 1-D system to gain the control of specific nanostructure since it different from bulk system. In this work, we fabricated two different metal pads (nickel/platinum), served as contact with silicon nanowires (NWs) to study nickel silicide/platinum silicide axial heterostructure through solid-state reaction. The as-fabricated Si NWs with two contact electrodes were annealed in ultrahigh vacuum in-situ transmission electron microscopy (UHV in-situ TEM) at 550℃ for observation of the reaction process. The structural information of dual silicide nanostructure was analyzed by spherical aberration corrected scanning transmission electron microscopy (Cs-corrected STEM) and we successfully got nickel silicide/platinum silicide axial heterostructure. With the understanding of the nickel silicide transformation mechanism in 1-D system, reliable 1-D NiSi nanostructures would be generally applicable to semiconductor industry.