Germanene is a 2-D material derived from germanium and related to graphene. As it is not stable outside the vacuum chambers in which is it produced, no real measurements of its electronic properties have been made. Scientists led by Prof. Justin Ye of the University of Groningen have now produced devices with stable germanene. The material is an insulator, and it becomes a semiconductor after moderate heating and a very good metallic conductor after stronger heating. The results were published in the journal Nano Letters.