Tight Binding Simulation of Quantum Transport in Interband Tunneling Devices

Matsuto Ogawa,Ryuichiro Tominaga,Tanroku Miyoshi

doi:10.1155/2001/31592

Abstract

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 an empirical tight binding theory has been used to take into account evanescent-wave matching at interfaces and realistic band structures. Comparison has been made between 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 the Si 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 other hand, in the GaAs ITD, there is small difference between the two models, because tunneling occurs between the conduction band and the valence band at F point. It is also found that the matching of evanescent electron modes is essentially necessary to include the valley-mixing effects at the tunneling interfaces.

Highlights

Interband tunneling diodes (ITD’s) or Esaki diodes have revived and attracted much attention again [1,2,3], since they are very suitable for device miniaturization below 0.1 tm, whereas, in such scale, conventional FETs suffer with the short channel effects and do not operate properly
Two propagating modes exist in the conduction band, whereas three modes exist in the valence band because the heavy hole band is doubly degenerated
The real bands, and the complex modes should be considered at a tunneling interface to match electron waves existing in the Si crystal, since two electron modes exist in the conduction band, whereas three modes exist in the valence band

Summary

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). A non-equilibrium Green’s function method based on empirical tight binding theory has been used to take into account evanescent-wave matching at interfaces and realistic band structures. Comparison has been made between the results of our multiband (MB) model and those of conventional two-band (2B) model. It is found that the current-voltage (I- V) characteristics of the Si ITD have considerably smaller peak current density than the conventional 2B model, since our MB model reflects correctly the indirect gap band structure. In the GaAs ITD, there is small difference between the two models, because tunneling occurs between the conduction band and the valence band at F point. It is found that the matching of evanescent electron modes is essentially necessary to include the valley-mixing effects at the tunneling interfaces

INTRODUCTION

We focus on quantum transport in a Si and a

CONCLUSION