Performance Enhancement in Uniaxially Strained Germanium–Tin FinTFET: Fin Direction Dependence

Abstract

We investigate the impact of uniaxial tensile stress on the performance of germanium-tin (GeSn) fin tunneling field-effect transistor (FinTFET) with fin rotating within (001) plane by numerical simulation. The uniaxial tensile stress with a magnitude of 1 GPa is always along the fin direction. Nonlocal empirical pseudopotential method and k · p method were utilized to calculate the energy band structure of GeSn. Dynamic nonlocal band-to-band tunneling (BTBT) algorithm was used to analyze the electrical characteristics of the strained GeSn FinTFETs with point and line tunneling modes. The substantial improvement of BTBT generation rate GBTBT and on-state current ION achieved in tensile-strained FinTFETs compared to the relaxed devices is attributed to the reduced direct bandgap EG in strained GeSn. The device performance enhancement induced by the stress demonstrates the obvious dependence on the fin direction and tunneling mode. Under 1 GPa uniaxial tensile stress, GeSn point-FinTFETs with (100) fin directions demonstrate an 11.7% I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ON</sub> enhancement as compared with the relaxed devices. For the strained GeSn line-FinTFETs, the devices with (110) fin directions obtain a 96.7% I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ON</sub> improvement, in comparison with the relaxed devices at V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">DD</sub> of -0.3 V.