A complementary metal-oxide semiconductor (CMOS) circuit and a method of fabricating the device are described. The circuit includes an n-channel field effect transistor (nFET), the nFET including a high-k dielectric layer on an interlayer. The CMOS circuit also includes a p-channel field effect transistor (pFET), the pFET including the high-k dielectric layer on the interlayer and additionally including an aluminum-based cap layer between the high-k dielectric layer and a pFET work function setting metal. Metal atoms from the cap layer do not intermix with the interlayer.