Growth of Silicide/Si Nanowire Heterostructures with Point and Line Contact Reactions

Metal silicides have been used as circuit elements in microelectronic devices to serve as ohmic contacts, Schottky barriers, gate electrodes, and interconnection among transistors in very-large-scale-integration (VLSI) technology. As the trend of device-miniaturization moves on, nanoscale metal silicides have attracted more interest and attention. Thus, there has been more and more research on silicide nanodots and silicide nanowires; the latter especially stirs widespread investigations, demonstrated to play an important role in nanodevices as shown in lots of literature. Here, we present our recent efforts in generating silicide/Si nanowire heterostructures through solid state reactions and the focus will be on point contact reactions, where single crystal silicide/Si/silicide nanowire heterostructures have been fabricated, in which huge strain was found in the middle Si layer, the dimension of which can be controlled down to sub-5 nm with atomically sharp interfaces between Si/silicides, overcoming the limit of conventional patterning process. Efficient and unique methods to form multiple nanoheterostructures of silicide/Si without lithography will be discussed as well. Additionally, it has been found that surface oxide affects the growth of these nanostructures significantly. Figure 1 High-resolution TEM image of a NiSi nanowire. The inset is the corresponding diffraction pattern with a [113] zone axis. (b) High-resolution TEM image of an epitaxial interface between NiSi and Si within a Si nanowire. (c) High angle annular dark-field image of the NiSi/Si/NiSi heterostructure. The bright image is NiSi and the dark image is Si. Figure 2 (a) to (c) In-situ TEM images showing the formation of multi-nanowire-heterostructures of NiSi/Si within a Si nanowire. The inset in (c) is the corresponding diffraction pattern with a [113] zone axis of a NiSi grain. (d) A schematic illustration of the growth of multinanowire-heterostructures of NiSi/Si within a Si nanowire. Abstract #145, 221st ECS Meeting, © 2012 The Electrochemical Society