Quantum well states and sizable Rashba splitting on Pb induced α-phase Bi/Si(111) surface reconstruction.

Quantum well states (QWSs) with sizable Rashba splitting are a promising quantum phase to achieve spin-split current for quantum computing and spintronics due to their controllable band structures. However, most QWSs were achieved upon metallic substrates with strong bulk electron transport. Developing semiconductor-based QWSs is preferable to minimize substrate interference. Here we report a Pb induced surface reconstruction on Bi/Si(111) α phase. Combining scanning tunneling microscopy (STM) and density functional theory (DFT) the atomic structure has been determined. QWSs and a sizable Rashba band splitting are predicted, with the latter comparable to what is found in other semiconductor heterostructures and an order of magnitude higher than that in Pb/Si(111) QWSs.