The pursuit of energy-efficient electronic devices has led to the exploration of novel transistor designs, including tunnel field-effect transistors (TFETs). In this master thesis, we embark on a comprehensive study of InAsGaSb TFETs, employing the nonequilibrium Green's function (NEGF) formalism, with a tight-binding (TB) model for band structure. The primary objective is to perform comparative appraisals of the TFET transcharacteristics evaluated with the TB-NEGF model developed in this thesis, versus models based on the Wentzel-Kramers-Brillouin (WKB) approximation coupled with k·p models, and with test cases from the literature. To this aim, we initially developed a robust computational code, based on the TB-NEGF formalism, to simulate the electronic behavior of InAsGaSb TFETs.