Bandgap engineering of group IV materials for complementary n and p tunneling field effect transistors

Abstract

Direct bandgap transition engineering using stress, alloying, and quantum confinement is proposed to achieve high performing complementary n and p tunneling field effect transistors (TFETs) based on group IV materials. The critical tensile stress for this transition decreases in Ge1−xSnx for Sn content 0≤x≤0.068, calculated with the Nonlocal Empirical Pseudopotential method. Direct sub eV bandgap leads to high ON current in both n and p Ge and Ge1−xSnx TFETs, simulated using the sp3d5s*-SO model. Ge and Ge1−xSnx show an advantage over III-V p TFETs achieving steep subthreshold operation, which is limited in III-V devices by their low density of electron states.