High Performance 400 °C p+/n Ge Junctions Using Cryogenic Boron Implantation

We report high performance Ge p⁺/n junctions using a single, cryogenic (-100 °C) boron ion implantation process. High activation>4 × 10²⁰ cm^-3 results in specific contact resistivity of 1.7 × 10^-8 Ω-cm² on p⁺-Ge, which is close to ITRS 15 nm specification (1 × 10^-8 Ω-cm²) and nearly 4.5× lower than the state of the art (8 × 10^-8 Ω-cm²). Cryogenic implantation is shown to enable solid-phase epitaxial regrowth and lower junction depth through amorphization of the surface Ge layer. These improvements in Ge p⁺/n junctions can pave the way for future high mobility Ge p-MOSFETs.