Abstract
The interfacial density of states and conductance of $\mathrm{Gd}\mathrm{As}∕\mathrm{Ga}\mathrm{As}∕\mathrm{Gd}\mathrm{As}$ junctions, where GdAs and GaAs are a semimetal and a semiconductor, respectively, are calculated using a full-orbital tight-binding model. The tunnel conductance of the junction is calculated using the Kubo formula at zero temperature assuming coherent tunneling of electrons. Emphasizing the role of interfacial states on the conductance, the following results are obtained. The interfacial states extend 2-4 atomic layers from the interface; however, the effect of the interfacial states on the conductance extends up to nearly 10 atomic GaAs layers, and nonmonotonic dependence of the tunnel conductance on the barrier thickness appears for thin GaAs layers. The height of the interfacial density of states does not necessarily correlate with the magnitude of the tunnel conductance. The matching between the Fermi surface of the leads and interfacial states governs the magnitude of the tunnel conductance. It is also found that the nonmonotonic dependence of the tunnel conductance is caused by an interference effect of the interface states existing at the two interfaces of GaAs layer.
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