Tight Binding Simulation of Quantum Transport in Interband Tunneling Devices

We have studied quantum transport in both Si and GaAs interband tunneling diodes(ITD's). In the simulation, a non-equilibrium Green's function method based anempirical tight binding theory has been used to take into account evanescent-wavematching at interfaces and realistic band structures. Comparison has been madebetween the results of our multiband (MB) model and those of conventional two-band(2B) model. As a result, it is found that the current–voltage (I–V) characteristics of theSi ITD have considerably smaller peak current density than the conventional 2B model,since our MB model reflects correctly the indirect gap band structure. On the otherhand, in the GaAs ITD, there is small difference between the two models, becausetunneling occurs between the conduction band and the valence band at F point. It isalso found that the matching of evanescent electron modes is essentially necessary toinclude the valley-mixing effects at the tunneling interfaces