Ni, Pt, and Ti stanogermanide formation on Ge0.92Sn0.08

The aim of this work is to provide a systematic and comparative study on the material characteristics and electrical contact performance for a germanium-tin (GeSn) alloy with a high percentage of Sn (8%). Thin metal films (10 nm) of Nickel (Ni), Titanium (Ti), or Platinum (Pt) were deposited on Ge
_0.92
Sn
_0.08
layers and subsequently annealed at different temperatures ranging from 300°C up to 500°C. Various experimental techniques were employed to characterize the metal morphology and the electrical contact behavior, with the intention of identifying the most promising metal candidate, in terms of low sheet resistance and low surface roughness, considering a low formation temperature. The investigations carried out show that for nano-electronic contact applications, nickel-stanogermanide (NiGeSn) turns out to be the most promising candidate among the three different metals analyzed. NiGeSn presents low sheet resistance combined with low formation temperatures, below 400°C; PtGeSn shows better thermal stability when compared to the other two options while, Ti was found to be unreactive below 500°C, resulting in incomplete TiGeSn formation.