Theoretical evidence of a superconducting transition in doped silicon and germanium driven by a variation of chemical composition

We present the first theoretical evidence of chemical composition driven superconductivity in acceptor-doped silicon and germanium, using density functional theory. We examine the concentration dependence of Tc in B-doped Si and Ge and predict that B-doped Ge is a superconductor with a slightly higher Tc than B-doped Si. We show that there is a critical concentration above which B-doped Si and Ge become superconducting and estimate it to be ∼2.6% in Si:B and ∼2.2% in Ge:B. Considering the Al-doped Si and Ge, we point out the decisive role of the chemical element in the hole-doping scenario.