6. Resonance and Transmission Coefficients Continued
Let us now consider a slightly more complicated case, double barrier scattering. The least complicated case
where interesting resonance effects show up. Figure 7 shows the geometry.
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| Figure 7: The geometry of the double barrier scattering region. |
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| Figure 8: Transmission coefficient for a double barrier as a function
of electron energy divided by barrier energy.
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The results for the single barrier seemed resonable, the transmission coefficient increased until it hit one
at E/V > 1. In order to completely pass the barrier the electron needed at least the energy of the barrier. Now
the results for the double barrier are quite unexpected. It seems that if we add a second barrier we actually
increase the transmission for some energies! There are particular electron energies below the barrier height
where the electron has a 100% chance of being transmitted, these are the resonance energies.
