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

The room-temperature effective mobilities of pseudomorphic Si/Si0.64Ge0.36/ Si p-metal-oxidesemiconductor field effect transistors are reported. The pe ak mobility in the buried SiGe channel increases with silicon cap thickness . It is argued that SiO2/Si interface roughness is a major source of scatte ring in these devices, which is attenuated for thicker silicon caps. It is also suggested that segregated Ge in the silicon cap interferes with the ox idation process, leading to increased SiO2/Si interface roughness in the ca se of thin silicon caps. (C) 2001 American Institute of Physics.