High Ge Content SiGe alloys: Doping and Contact Formation

Abstract

High Ge content SiGe alloys or pure Ge are essential components of future microelectronics (high performance p-channels) and optoelectronics/microelectronics (on-chip and chip to chip communication) integration scenarios. The successful integration with Si based circuits requires process compatibility. Here we report specifically on recent results with high n and p doping of Ge and contact formation with Al and silicide/germanide metals. Highly Sb and B doped epitaxial layers (/cm3) are grown at low temperatures (< 400oC) and complete electrical activation of dopants is proven by SIMS and TLM measurements. Metal contacts on p-Ge are easily fabricated as Ohmic ones, whereas n-Ge contacts are more critical. We explain this by the Fermi level pinning near the valence band, and the strong influence of thin interface layers on the strength of Fermi level pinning.