Intrinsic Robustness of TFET Subthreshold Swing to Interface and Oxide Traps: A Comparative PBTI Study of InGaAs TFETs and MOSFETs

We study the positive bias temperature instability (PBTI) of InGaAs tunnel-FETs (TFETs) with two different indium fractions (53% and 70%) and compare with reference MOSFETs, using the same gate stack. While identical threshold voltage instability is found irrespective of the device type, the subthreshold swing (SS) of the TFETs is found to be more robust against PBTI as compared with MOSFETs. With the aid of comprehensive TCAD simulations, we show that the SS of a TFET is intrinsically less sensitive to interface/oxide border traps, thanks to the narrow energy range swept by the channel Fermi level during the OFF-to-ON transition of the device operation. Moreover, only traps located within ~20 nm from the tunnel junction can affect the SS.