Significance of Multivalley and Nonparabolic Band Structure for GeSn TFET Simulation

It is well known that there is a critical Sn content for a GeSn alloy, at which the conduction band edges at L and Γ symmetry points are aligned in energy. For GeSn tunnel FET (TFET) simulations, with a given donor concentration, this paper reveals that simulations neglecting the multivalley and nonparabolic band structure would incorrectly predict the subthreshold slope (SS) and the off-currents. We highlight the indispensability of the consideration of the multivalley band structure of GeSn for TFET simulations. This paper provides the required parameters, which may be useful for numerical simulations of other optoelectronic and electronic GeSn devices.