Effective mobilities in pseudomorphic Si/SiGe/ p-channel metal-oxide-semiconductor field-effect transistors with thin silicon capping layers

The room-temperature effective mobilities of pseudomorphic Si/Si 0.64 Ge 0.36/Si p-metal-oxide-semiconductor field effect transistors are reported. The peak mobility in the buried Si/Ge channel increases with silicon cap thickness. It is argued that SiO2/Si interface roughness is a major source of scattering in these devices, which is attenuated for thicker silicon caps. It is also suggested that segregated Ge in the silicon cap interferes with the oxidation process, leading to increased SiO2/Si interface roughness in the case of thin silicon caps