Electron tunneling between a metal and a semiconductor: Characteristics of Al-Al₂O₃-SnTe and -GeTe junctions

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 degenerate p type 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-Al 2O3-SnTe and -GeTe have been fabricated and their I-V characteristics 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. © 1967 The American Institute of Physics.