In favor of the Wigner function method we note that physically a finite coherence length is more adequate. Results from elementary tunneling theory using Schrödinger formulations tend to overestimate the peak to valley ratio [Fre90], [RFK89].

A small change in the coherence length can already have a significant effect on the peak to valley ratio. This is shown in figure 10.4, where the coherence length is increased from to for a resonant tunneling diode [KKNS03] which leads to a 50 percent increase in the peak to valley ratio.

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R. Kosik: Numerical Challenges on the Road to NanoTCAD