Performance improvement in novel germanium–tin/germanium heterojunction-enhanced p-channel tunneling field-effect transistor

• GeSn heterostructure-enhanced tunneling field-effect transistor (HETFET) is designed and investigated.
• GeSn HE-TFET demonstrates an improved ION and subthreshold swing compared to the homo TFET at VDD of 0.3 V.
• Impact of Sn composition on GeSn HE-TFET is studied.

We design a novel GeSn-based heterojunction-enhanced p-channel tunneling field-effect transistor (HE-PTFET) with a Ge0.92Sn0.08/Ge heterojunction located in channel region, at a distance of LT–H from the Ge0.92Sn0.08 source-channel tunneling junction (TJ). HE-PTFETs demonstrate the negative shift of onset voltage VONSET, the steeper subthreshold swing S, and the improved on-state current ION compared to Ge0.92Sn0.08 homo-PTFET. At low VGS, the suppression of BTBT due to the widening of the tunneling barrier caused by the heterojunction leads to a negative shift of VONSET in HE-PTFETs. At high VGS, ION enhancement in HE-PTFETs is achieved over the homo device, which is attributed to the confinement of BTBT in Ge0.92Sn0.08 source-channel TJ region by the heterojunction, where the short tunneling paths lead to a high tunneling probability. Due to the steeper average S, HE-PTFET with a 6 nm LT–H achieves a 4 times higher ION compared to homo device at a VDD of −0.3 V.