Strain and Hole-Density Dependence of Hole Mobility in Strained-Ge Modulation-Doped Structures

Ge channel is attracting much attention because of its inherent high mobility. The compressive strain, which is introduced by growing Ge layers on strain-relaxed SiGe buffer layers, is, moreover, able to increase the mobility significantly. Here, we studied the strain dependence of the hole mobility in strained-Ge modulation-doped (MOD) structures by fabricating Ge layers on planarized SiGe buffer layers with various Ge compositions. The hole density dependence was also investigated by utilizing backgate bias