p-n junction

pn-liitos puhekieltä An interface between a p-type and n-type semiconductor; used to create junction diodes and junction transistors
2011, (w) & Jeff Forshaw, The Quantum Universe, Allen Lane 2011, p. 168:

In this way a pn-junction can be used as a diode – it can allow a current to flow, but only in one direction.