Influences of energy band lineup at the tunneling junction on the performance of GaAsxSb1−x/InyGa1−yAs heterojunction tunneling field-effect transistors (HTFETs) have been investigated using TCAD simulations. The results show that devices with low off-current, high on-current, and low subthreshold swing over a wide current range can be achieved simultaneously based on GaAs0.51Sb0.49/InxGa1−xAs/In0.53Ga0.47As heterojunctions.