Valence band structure of biaxial strained Germanium for hole transport calculation

A comprehensive study of hole mobility in Germanium material dependence on strained substrate orientations and carrier transport directions was performed in this paper. The heavy hole, light hole, and spin-orbit bands are included in the calculation of valence band structure. The biaxial strain induced valence band edge energy splitting and effective mass change were evaluated as well as their impacts on the hole mobility in Germanium were analysed. The results show that the optimum strained substrate orientation and carrier transport direction configuration are biaxial compressive strained on the (110) oriented substrate and in-plane [(1) over bar 10] as a hole transport direction, the configuration of which has the maximum hole mobility under the same strained level in comparison with others. The reason for high hole mobility is also explored. The current research is helpful to design the high performances p-channel MOSFETs in the strained Germanium system. The hole mobility of Germanium versus strain level under different biaxial strained substrate and transport directions configurations