In this letter, we propose a heterostructure design for tunnel field effect transistors with two
low direct bandgap group IV compounds, GeSn and highly tensely strained Ge in
combination with ternary SiGeSn alloy. Electronic band calculations show that strained Ge,
used as channel, grown on Ge 1− x Sn x (x> 9%) buffer, as source, becomes a direct
bandgap which significantly increases the tunneling probability. The SiGeSn ternaries are
well suitable as drain since they offer a large indirect bandgap. The growth of such …