  Solid state electronics relies on the intentional introduction of impurity
atoms or dopants into a semiconductor crystal and/or the formation of junctions
between different materials (heterojunctions) to create rectifiers, potential
barriers, and conducting pathways. With these building blocks, switching and
amplification of electrical currents and voltages is achieved. As
miniaturization continues to ultra-scaled transistors with critical dimensions
on the order of ten atomic lengths, the concept of doping to form rectifying
junctions fails and heterojunction formation becomes extremely difficult. Here
it is shown there is no need to introduce dopant atoms nor is the formation of
a heterojunction required to achieve the fundamental electronic function of
current rectification. Ideal diode behavior or rectification is achieved for
the first time solely by manipulation of quantum confinement in approximately 2
nanometer thick films consisting of a single atomic element, the semimetal
bismuth. Crucially for nanoelectronics, this new quantum approach enables room
temperature operation.
