Investigation of TFETs with Vertical Tunneling Path for Low Average Subthreshold Swing

In this paper we analyze the capabilities in terms of average subthreshold swing and on-current of Si0.50Ge0.50/Si heterostructure n-TFETs with vertical tunneling path, utilizing an air bridge design to minimize source-drain leakage. We show that the on-current is line tunneling dominated and proportional to the source-gate overlap area. In order to obtain a low average subthreshold swing the onsets of diagonal point tunneling and line tunneling have to be merged closely, which is best achieved with a moderate counter doping in the channel. As a result average slopes of 87 mV/dec over 4 decades of Id and Ion/Ioff ratios of larger than 106 are obtained.