Work-Function Variation Effects of Tunneling Field-Effect Transistors (TFETs)

The work-function variation (WFV) effects of tunneling field-effect transistors (TFETs) are discussed for the first time. According to the 3-D device simulation results, TFETs are less immune to the WFV than metal–oxide–semiconductor FETs (MOSFETs) in terms of subthreshold swing
$(S)$
and threshold voltage
$(V_{\rm th})$
. TFETs show
${\sim}{1.4}\times$
larger
$V_{\rm th}$
standard deviation
$(\sigma V_{\rm th})$
and
${\sim}{4.6}\times$
larger
$S$
standard deviation
$(\sigma S)$
than MOSFETs at high drain voltage
$(V_{\rm D})$
. It is because TFET characteristics are mainly determined by WF values of metal grains near to the source region where band-to-band tunneling occurs.