The effect of sulfur passivation of the surface of Ge0.83Sn0.17 is investigated. X-ray photoelectron spectroscopy (XPS) was used to examine the interfacial property between HfO2 and Ge0.83Sn0.17. Sulfur passivation is effective in reducing both the Ge oxides and Sn oxides formation and the Sn atoms segregation. In addition, sulfur passivation reduces the interface trap density Dit at the HfO2/Ge0.83Sn0.17 interface from the valence band edge to the midgap. After the implementation of sulfur passivation, Ge0.83Sn0.17 p-MOSFETs show improved subthreshold swing S and effective hole mobility μeff. 25% μeff enhancement can be observed in Ge0.83Sn0.17 p-MOSFETs with sulfur passivation at a high inversion carrier density Ninv of 1 × 1013 cm−2.
Part of the book: Design, Simulation and Construction of Field Effect Transistors