A method of performing an early PTS implant and forming a buffer layer under a bulk or fin channel to control doping in the channel and the resulting bulk or fin device are provided. Embodiments include forming a recess in a substrate; forming a PTS layer below a bottom surface of the recess; forming a buffer layer on the bottom surface and on side surfaces of the recess; forming a channel layer on and adjacent to the buffer layer; and annealing the channel, buffer, and PTS layers.