Abstract
Nickel germano-silicide (NiSiGe) contact was formed on silicon-germanium ( or SiGe) epilayer with 26% Ge, grown on (100) substrate. We report the tuning of the effective Schottky barrier height (SBH) of holes at the junction to sub- by the introduction of aluminum (Al) using ion implantation and its segregation at the interface after germano-silicidation. The effective SBH decreases with increasing concentration of Al at the interface. We demonstrate the achievement of one of the lowest reported hole SBHs for NiSiGe on SiGe of , which is extremely promising for application in -type metal oxide semiconductor field-effect transistors. The presence of Al does not affect the sheet resistance or the low-resistivity nickel mono-germano-silicide phase of the NiSiGe film. Our results indicate the possibility of an electric dipole at the interface, introduced by Al atoms, which is responsible for the SBH modulation. Increase in thickness of nickel used for germano-silicidation increases the effective SBH. The increase in the Al implant dose reduces the effective SBH but degrades the SiGe epilayer by amorphizing it to a greater depth. Thus, a trade-off exists in choosing the Al implant dose and the nickel thickness needed to consume the amorphized SiGe for maximum device performance.
Published Version
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