Dopant Segregation and Nickel Stanogermanide Contact Formation on Source/Drain

P⁺Ge_1-xSn_x is a promising source and drain (S/D) stressor material for Ge p-MOSFETs, and an S/D material in Ge_1-xSn_x channel p-MOSFETs. In this paper, we investigate the dopant segregation (DS) effects in the stanogermanidation of p⁺Ge_0.947Sn_0.053 (boron-doped). A study comparing the contact resistance R_C of nickel stanogermanide [Ni(Ge_1-xSn_x) or Ni(GeSn)] contact on p⁺Ge_1-xSn_x and nickel germanide (NiGe) contact on p⁺ Ge was performed. A more pronounced DS effect is achieved during the stanogermanidation in comparison with the NiGe/p⁺Ge control. R_C is 44% lower in the Ni(Ge_1-x Sn_x)/p⁺GeSn structure as compared to the NiGe/p⁺Ge control. The reduced R_C is attributed to a more significant DS effect and the lower bandgap of Ge_1-xSn_x as compared with Ge.