Abstract: Systems and methods are provided for fabricating a semiconductor device structure. An example semiconductor device structure includes a channel layer formed of a Germanium compound having a Germanium concentration B formed on a semiconductor substrate having a Germanium concentration of A, the Germanium concentration of the substrate A being less than the Germanium concentration of the channel layer B. The structure further includes a capping layer formed to separate the channel layer from a metal gate, the capping layer having a Germanium concentration of C, the Germanium concentration of the channel layer B being greater than the Germanium concentration of the capping layer C.