Optimizing the density of delta doped Al in Si toward superconductivity

Potential superconductivity in heavily delta-doped Al in Si, with a predicted T_c ≈ 6 K, would be an attractive candidate for bridging superconducting QIS with silicon-based quantum devices for a new generation of solid-state quantum computing. In this talk, we present the material properties and electrical characterization of our 2^nd generation super-saturated Al delta doped layers. Solid phase epitaxy recovery (SPER) with an improved incorporation anneal are conducted during material synthesis followed by fabrication of mesa-etched hall bars to study the carrier density, mobility and temperature dependence of these properties. So far, a maximum 2D density of 3.2x10¹⁴ cm^-2 with dopant activation close to 100% has been achieved, doubling the density compared to our 1^st generation delta layer. Secondary ion mass spectroscopy (SIMS), scanning tunneling microscopy and magneto-transport results are all presented to compare the impact of different growth processes on dopant diffusion and segregation in Si.