Calibration of the Effective Tunneling Bandgap in GaAsSb/InGaAs for Improved TFET Performance Prediction

The effective bandgap for heterojunction band-to-band tunneling (E
_g,eff
) is a crucial design parameter for a heterojunction tunneling FET (TFET). However, there is significant uncertainty on E
_g,eff
, especially for In
_0.53
Ga
_0.47
As/GaAs
_0.5
Sb
_0.5
. This makes the prediction of TFET performance difficult. We calibrate E
_g,eff
by fabricating heterojunction p+/i/n+ diodes, comparing the simulated and the measured current-voltage and capacitance-voltage curves, while taking E
_g,eff
as a fitting parameter. Our calibration significantly reduces the uncertainty on E
_g,eff
compared with the range found in the literature. The comparison with the previous work on highly doped heterojunction diodes suggests that dopant-dependent bandgap narrowing reduces E
_g,eff
and therefore significantly impacts the performance of highly doped TFET.