U-Gate SiGeSn/GeSn Heterojunction Tunneling Field-Effect Transistors

Abstract

U-gate SiGeSn/GeSn heterojunction p-channel tunneling FETs (hetero-PTFETs) with a lightly doped spacer inserted between GeSn channel and SiGeSn drain are designed and characterized. The ON-state I _ON and OFF-state I _OFF currents can be separately controlled by band-to-band tunneling (BTBT) and source-to-drain tunneling (SDT), respectively. I _OFF , average subthreshold swing, and I _ON /I _OFF ratio characteristics are improved by increasing the thickness of spacer and using SiGeSn spacer instead of GeSn. I _ON is enhanced by increasing Sn composition and reducing spacer thickness. Thus it can be seen that the parameters of spacer are key factors influencing the electrical properties of the TFETs.