Tuning superconductivity in nanosecond laser annealed boron doped $Si_{1-x}Ge_{x}$ epilayers

• DOI: 10.48550/arxiv.2404.02748
• Publication Date: 2024-04-03
• Authors: Sukhendu Nath; Ilke Simsek Turan; L. Desvignes; L. Largeau; O. Mauguin; Marc Túnica; Michele Amato; C. Renard; Géraldine Hallais; D. Débarre; F. Chiodi
• Keywords: Nanosecond

Superconductivity in ultra-doped $Si_{1-x}Ge_{x}:B$ epilayers is demonstrated by nanosecond laser doping, which allows introducing substitutional B concentrations well above the solubility limit and up to $7\,at.\%$. A Ge fraction $x$ ranging from 0 0.21 incorporated $Si:B$ : 1) through a precursor gas Gas Immersion Laser Doping; 2) ion implantation, followed annealing; 3) UHV-CVD growth of thin layer, annealing. The 30 nm 80 thick display superconducting critical temperatures $T_c$ tuned between 0.6 K. Within BCS weak-coupling theory, evolves exponentially with both density states electron-phonon potential. While doping affects both, increase carrier tensile strain, incorporation addressing independently lattice deformation influence on superconductivity. To estimate parameter modulation Ge, Vegard's law validated for ternary $SiGeB$ bulk alloy Density Functional Theory calculations. Its validity furthermore confirmed experimentally X-Ray Diffraction. We highlight global linear dependence vs. parameter, common $Si_{1-x}Ge_{x}:B$, $\delta T_c/T_c \sim 50\,\%$ a/a 1\,\%$.