Superconductor-insulator transition controlled by annealing in Ga implanted Si

摘要

Heavily Ga implanted Si nanolayers covered with a thin SiO_2 layer exhibit a superconductor-insulator transition in dependence on annealing conditions. The transition characteristics resemble those of ultrathin quench-condensed metal films although the implanted layer differs clearly in composition, width, and nanostructure. This implies a general physical mechanism for the superconductor-insulator transition in thin, disordered layers which is supposed to be a quantum phase transition between dual states-the superconducting and the superinsulating one. There is a resistance criterion for the phase transition closely associated with a critical hole concentration.