Silicon to nickel-silicide axial nanowire heterostructures for high performance electronics

Silicon to nickel disilicide axial nanowire (NW) heterostructures have been fabricated and investigated extensively. To this end, intrinsic Si-NWs were grown by chemical vapor deposition using Au as the catalyst. The Si-NWs were contacted with Ni reservoirs so that upon annealing Ni diffused axially into the NWs. Single-crystalline NiSi 2 NW segments were formed at the diffusion path of Ni as proven by high-resolution transmission electron microscopy images. Further, the axial NiSi 2 to Si interfaces showed a sharpness of a couple of nanometers. Fully silicided NiSi 2 -NWs had maximal resistivities of 98 μΩ cm and conducted current densities of up to 205 MA/cm 2 before breakdown. Controlled silicidation from both NW ends gave NiSi 2 /Si/NiSi 2 axial NW heterostructures, which were implemented to fabricate Schottky contact field effect transistors (FET). The n ++ -substrate was used as a common back gate and the Si to NiSi 2 interfaces formed the Schottky source- and drain-(S/D) contacts to the active region. These Si-NW SB-FETs exhibited p-type behavior, and current densities in the on state of up to 0.8 MA/cm 2 for 1 V bias, the drain current could be modulated over a range of 10 7 . Moreover, the use of thin gate dielectrics enabled inverse subthreshold slopes as low as 110 mV/dec. These data show an efficient gate control over the devices by only using a back gate, due to an enhanced gate field coupling to the tip-like S/D-Schottky contacts.