The present invention relates to a heterojunction tunneling effect transistor (TFET), which comprises spaced apart source and drain regions with a channel region located therebetween and a gate stack located over the channel region. The drain region comprises a first semiconductor material and is doped with a first dopant species of a first conductivity type. The source region comprises a second, different semiconductor material and is doped with a second dopant species of a second, different conductivity type. The gate stack comprises at least a gate dielectric and a gate conductor. When the heterojunction TFET is an n-channel TFET, the drain region comprises n-doped silicon, while the source region comprises p-doped silicon germanium.