Experimental clarification of orientation dependence of germanium PMOSFETs with Al2O3/GeOx/Ge gate stack

An extensive and complete experimental investigation with a full layout design of the channel direction was carried out for the first time to clarify the orientation dependence of germanium p-channel metal—oxide—semiconductor field-effect transistors (PMOSFETs). By comparison of gate trans-conductance, drive current, and hole mobility, we found that the performance trend with the substrate orientation for Ge PMOSFET is (110)>(111) ~ (100), and the best channel direction is (110)/[110]. Moreover, the (110) device performance was found to be easily degraded as the channel direction got off from the [110] orientation, while (100) and (111) devices exhibited less channel orientation dependence. This experimental result shows good matching with the simulation reports to give a credible and significant guidance for Ge PMOSFET design.