Abstract Field-effect transistors based on band-to-band tunneling (TFETs) have recently attracted a great deal of interest. The strong interest stems from the fact that TFETs potentially allow the realization of transistors with superior switching behavior compared to conventional metal-oxide semiconductor FETs and hence allow reducing the operational voltage as well as the off-state leakage current. As a result, integrated circuits based on TFETs potentially exhibit a substantially reduced dynamic and static power consumption and are therefore particularly well suited for low-power, mobile applications. However, although tremendous progress has been made recently, experimental realizations so far still lack a satisfying performance. While a number of apparent performance boosters have been identified in recent studies, their impact on the performance of TFETs becomes rather intricate and involved when spatial dimensions are reduced to the nanoscale such as in nanowire TFETs. The aim of this chapter is to study the various dependences isolated from each other in order to illuminate the interdependencies, impact, and effectiveness of different TFET performance boosters.