Superconductivity of metal-induced surface reconstructions on silicon

Recent progress in superconducting metal-induced surface reconstructions on silicon is reviewed, mainly focusing on the results of the author's group. After a brief introduction of an ultrahigh-vacuum(UHV)low-temperature (LT)-compatible electron transport measurement system, direct observation of the zero resistance state for the Si(111)(root 7 x root 3)-In surface is described, which demonstrates the existence of a superconducting transition in this class of two-dimensional (2D) materials. The measurement and analysis of the temperature dependence of the critical current density indicate that a surface atomic step works as a Josephson junction. This identification is further confirmed by LT-scanning tunneling microscopy (STM) observation of Josephson vortices trapped at atomic steps on the Si(111)(root 7 x root 3)-In surface. These experiments reveal unique features of metal-induced surface reconstructions on silicon that may be utilized to explore novel superconductivity.