A device and method for manufacturing a Si-based high-mobility CMOS device is provided. The method includes the steps of: (i) providing a silicon substrate having a first insulation layer on top and a trench into the silicon; (ii) manufacturing a III-V semiconductor channel layer above the first insulation layer by depositing a first dummy layer of a sacrificial material, covering the first dummy layer with a first oxide layer, and replacing the first dummy layer with III-V semiconductor material by etching via holes in the first oxide layer followed by selective area growth; (iii) manufacturing a second insulation layer above the III-V semiconductor channel layer and uncovering the trench; (iv) manufacturing a germanium or silicon-germanium channel layer above the second insulation layer by depositing a second dummy layer of a sacrificial material, covering the second dummy layer with a second oxide layer, and replacing the second dummy layer with germanium or silicon-germanium by etching via holes in the second oxide layer followed by selective area growth.