The process of electron tunneling from a metal to a semiconductor through an insulating layer is considered. Theoretical current‐voltage expressions have been obtained, in particular, for the case when the semiconductor is degenerateptype and the conduction band of the insulator provides the dominant tunneling barrier. The existence of an energy gap and a relatively small Fermi energy in the semiconductor makes the current highly asymmetrical with respect to the polarity of the applied voltage. Experimentally, junctions of Al‐Al2O3‐SnTe and −GeTe have been fabricated and theirI‐Vcharacteristics measured at 4.2°K. Good agreement is observed between the theoretical and experimental current behavior, from which energy parameters of the semiconductors and the barrier relations of the junctions have been obtained.