Seeking superconductivity with new, two-dimensional dopants super-saturated in silicon

Realizing superconducting Josephson junctions within group-IV semiconductors would herald a new era of solid-state quantum computing. For some acceptors, super-saturated doping has been demonstrated to superconduct, e.g. boron-doped silicon having a T_c of 0.6 K [1]. Here we explore the possibility of superconductivity in similar material systems using both n-type (antimony) and p-type (aluminum) delta-doped layers. Low-temperature molecular beam epitaxy (MBE) has been used to embed atomically thin (2D) layers of antimony and aluminum atoms with dopant densities on the order of (10¹³ - 10¹⁴) cm^-2. Mesa-etched Hall bar devices are fabricated on these delta layers and magnetotransport measurements at 4 K will be presented to study the material properties, such as carrier concentration and mobility. Temperature dependent measurements below 500 mK will be carried out in a dry dilution refrigerator to test for superconductivity. Comparisons between different dopant systems will also be presented.

[1] Marcenat, C. et al. Phys. Rev. B 81, 020501–020504(R) (2010).