The tunneling time τ
as the number of cells n in a SL is varied. (a) Saturation of τ
for electron energies E=0.15 eV and E=0.2 eV in the gap. (b) The energy is close to a resonant band-edge. In this case, more resonances appear as n is increased with the energy fixed. No Hartman effect can be inferred from this figure.