Study of effect of oxide thickness variation on electrical parameters and high frequency characteristics induced by work-function variation for delta-doped germanium-source vertical TFET

Abstract

In this paper, we use a 3D technology computer-aided design device simulator to conduct an investigation into the impact on oxide thickness variation, based on parameters, such as threshold voltage (σV TH ), subthreshold swing (σSS), on current (σI ON ), off current (σI OFF ), current ratio σ(I ON /I OFF ), transconductance (σg m ), total gate capacitance (σC gg ), and cut-off frequency (σf T ), induced by Titanium nitride (TiN) metal gate/high-κ stack work-function variability (WFV) in a delta-doped layer Germanium-source vertical tunnel field-effect transistor (vTFET). We note that WFV has a substantial impact on electrical parameters as well as high frequency characteristics, in relation to gate insulator thickness variation. The distribution of V TH is nearly Gaussian for smaller metal grain sizes, whereas it appears bi-modal for larger grain sizes. However, the average effect has an insignificant impact on the WFV-induced threshold-voltage variation for vTFET architectures.