At present, the reduction in the physical size of traditional metal oxide semiconductor field effect transistors (MOSFETs) is limited because the subthreshold swing (SS) cannot be reduced below 60 mV/decade at 300 °K K. Power dissipation remains a critical concern in nano-scaled electronic circuits. Although miniaturization of the supply voltage can help diminish the energy required for switching, modern integrated circuits still rely on field effect transistors (FETs) that need a gate voltage of approximately 60 mV to achieve a one order of magnitude increase in drain current at 300 °K. Tunnel FETs (TFETs) overcome this limitation of traditional MOSFETs on account of their quantum mechanical band-to-band (BTBT) tunneling, lower sub-KT/q SS (< 60 mV/decade), low OFF-state leakage current (IOFF), and improved ION/IOFF switching current ratio. On the flip side, TFETs suffer from higher ambipolarity and lower ON-state current issues. Ambipolarity refers to the conductivity of the device in both gate polarities (positive and negative). This issue inhibits TFETs from switching off completely at zero gate voltage. Therefore, the usefulness of TFETs has been limited in complementary digital circuits. Several engineering techniques have been reported to suppress ambipolarity. This chapter reviews and compares several engineering techniques to lessen the ambipolarity of TFETs and increase the ION/IAmb ratio.