In this work, a high-performance compound semiconductor tunneling field-effect transistor (TFET) based on germanium (Ge)/gallium arsenide (GaAs) heterojunction with a tunneling-boost layer is investigated. The tunneling-boost layer in the source-side channel alters the energy bandgap structure between the source and the channel, which affects current drivability considerably. It is shown that controlling the lengths of the boosting layer (thin n GaAs layer) and lightly doped p-type channel (p-GaAs) also has substantial effects on adjusting Vth without complications arising from shifting metal workfunction. Furthermore, we evaluate device performances such as on-state current (Ion), subthreshold swing (S), intrinsic delay time , and cut-off frequency (fT). The proposed TFET with an n-GaAs length of 12 nm showed an S of 27 mV/dec and approximately 3 times higher Ion than that of the device without a boosting layer. Moreover, it is confirmed from the extracted excellent radiofrequency (RF) parameters that the proposed device is suitable for RF applications.