An embodiment includes a device comprising: first and second fins adjacent one another and each including channel and subfin layers, the channel layers having bottom surfaces directly contacting upper surfaces of the subfin layers; wherein (a) the bottom surfaces are generally coplanar with one another and are generally flat; (b) the upper surfaces are generally coplanar with one another and are generally flat; and (c) the channel layers include an upper material and the subfin layers include a lower III-V material different from the upper III-V material. Other embodiments are described herein.