We investigate charge transport of $pn$ and $npn$ junctions made from silicene, a Si analogue of graphene. The conductance shows the distinct gate-voltage dependencies peculiar to the topological and nontopological phases, where the topological phase transition is caused by external electric field. Namely, the conductance is (not) suppressed in the $np$ ($nn$) regime when both sides are topological, and in the $nn$ ($np$) regime when one side is topological and the other side is nontopological. Furthermore, we find that the conductance is almost quantized to be 0, 1, and 2. Our findings will open a new way to nanoelectronics based on silicene.

• Received 23 March 2013

DOI:https://doi.org/10.1103/PhysRevB.88.085322