"Semi-Conductors are named this due to their ability to conduct highly in "One Direction", and conduct very poorly in "The Other Direction"."
AFAIK, they are named "semiconductors" because their bulk conductivity falls somewhere between that of conductors and insulators.
The unidirectional electron flow thing requires a junction between P and N type semiconductors, or regions with differing impurities which cause localized deficiencies or surplusses of electrons.
