Tunneling field effect transistors (TFETs) including a variable bandgap channel are described. In some embodiments, one or more bandgap characteristics of the variable bandgap channel may be dynamically altered by at least one of the application or withdrawal of a force, such as a voltage or electric field. In some embodiments the variable bandgap channel may be configured to modulate from an ON to an OFF state and vice versa in response to the application and/or withdrawal of a force. The variable bandgap channel may exhibit a bandgap that is smaller in the ON state than in the OFF state. As a result, the TFETs may exhibit one or more of relatively high on current, relatively low off current, and sub-threshold swing below 60 mV/decade.