Relaxed germanium-tin P-channel tunneling field-effect transistors fabricated on Si: impacts of Sn composition and uniaxial tensile strain

摘要

In this work, relaxed GeSn p-channel tunneling field-effect transistors (pTFETs) with various Sn compositions are fabricated on Si. Enhancement of on-state current I ON with the increase of Sn composition is observed in transistors, due to the reduction of direct bandgap E G. Ge 0.93Sn0.07 and Ge 0.95Sn0.05 pTFETs achieve 110% and 75% enhancement in I ON, respectively, compared to Ge 0.97Sn0.03 devices, at V GS?-?V TH = V DS = -?1.0 V. For the first time, I ON enhancement in GeSn pTFET utilizing uniaxial tensile strain is reported. By applying 0.14% uniaxial tensile strain along [110] channel direction, Ge 0.95Sn0.05 pTFETs achieve 12% I ON improvement, over unstrained control devices at V GS?-?V TH = V DS = -?1.0 V. Theoretical study demonstrates that uniaxial tensile strain leads to the reduction of direct E G and affects the reduced tunneling mass, which bring the G BTBT rising, benefiting the tunneling current enhancement in GeSn TFETs.