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The model of charge carrier transport in ferromagnet/wide-gap semiconductor/
ferromagnet nanostructure based on two-band Franc-Keine model and phase function method
was proposed. It is determined that tunneling barrier, formed by the gap of wide-gap
semiconductor, does not represent potential step, but the energy band gap. Its upper border is
the bottom of the conduction band EC, and the bottom part is the top of the valence band EV.
Inside this zone wave vector of the electron is an imaginary value. According to
the dispersion law, states located in the midgap sustain the largest attenuation. That is why
when the Fermi level of the analyzed structure lies in the bottom part of the band-gap, bias
voltage V shifts levels of the tunneling electrons to a low barrier area. This shifting is
the reason of the tunneling current reduction and leads to the negative differential resistance
effect. It is shown that areas of the negative differential resistance effect appear at the current-
voltage bias dependence at qV > EF. Here areas of negative differential resistance should be
expected at the voltage values higher than Fermi energy value of the emitting electrode for
the zone electrons with the spin-up.
Keywords: ferromagnetic; wide-gap semiconductor; two-band model; phase function method; negative differential resistance; nanostructure |
full paper (pdf, 1072 Kb)