Pt Germanidation of a-Ge:H Enhanced by Remote Hydrogen Plasma Exposure

We have studied germanidation of hydrogenated amorphous Ge films (a-Ge:H) by exposing to remote plasma of pure hydrogen (RP-H$_{2})$ without external heating after Pt film deposition. Raman scattering signals attributable to Pt-Ge phase were observable within the first 1 min of RP-H$_{2}$ exposure. In exposing for 20 min, full-germanidation of $\sim $80nm-thick a-Ge:H was achieved and its resultant sheet resistance as low as $\sim $4.5$\Omega $/sq. was obtained. X-ray diffraction patterns confirm the formation of Pt$_{2}$Ge in the initial stages of the reaction between Pt and a-Ge:H and subsequent phase transition to PtGes. The driving force of such germanidation reaction is attributed to heat transfer caused by efficient recombination of atomic hydrogen on the Pt surface.