We present the epitaxial growth of Ge and Ge 0.94 Sn 0.06 layers with 1.4% and 0.4% tensile strain, respectively, by reduced pressure chemical vapor deposition on relaxed GeSn buffers and the formation of high-k/metal gate stacks thereon. Annealing experiments reveal that process temperatures are limited to 350 °C to avoid Sn diffusion. Particular emphasis is placed on the electrical characterization of various high-k dielectrics, as 5 nm Al 2 O 3 , 5 nm HfO 2 , or 1 nmAl 2 O 3 /4 nm HfO 2 , on strained Ge and strained Ge 0.94 Sn 0.06 . Experimental capacitance− voltage characteristics are presented and the effect of the small bandgap, like strong response of minority carriers at applied field, are discussed via simulations.