Superconductivity in doped cubic silicon

Superconducting silicon Superconductivity has turned up in some unlikely materials such as diamond. But it has been disappointingly absent in silicon. The conductivity of silicon, the archetypal semiconductor, can be varied by many orders of magnitude by 'doping' — adding traces of other elements. Doping with boron atoms, for example, turns the semiconductor into a metal, so the challenge is to squeeze in even more boron so that a current can flow without resistance. That goal has now been achieved, using a technique called gas immersion laser doping. In the process, silicon is made molten and solidified repeatedly while boron atoms diffuse into the material at each cycle. Doped in this way, with a boron concentration of several per cent, silicon becomes superconducting below 0.35 K.