Impact of Strain on Tunneling Current and Threshold Voltage in III-V Nanowire TFETs

A simulation study on the effects of different strain configurations on n-type III-V-based nanowire tunnel-FETs is presented, with the aim to determine optimal strain conditions to enhance device performance. We find that both the biaxial tensile and the uniaxial compressive stress shift up the valence band. Biaxial stress, however, lowers the conduction band as well, thus providing the largest reduction of the energy bandgap. Instead, the gap variation is limited for the biaxial compressive and uniaxial tensile strains. Moreover, for these strain conditions, the lowest conduction subband is not connected to the highest valence subband via the imaginary wave vector but to a lower one. This leads to an effective bandgap higher than the expected, which reflects into a large threshold increase and a degradation of the ON-state current.