Implementations described herein provide a method that includes implanting a dopant and carbon in a portion of a substrate of a semiconductor device. The method also includes depositing a first silicon-based layer on the portion of the substrate, the first silicon-based layer reacting with the carbon to form a diffusion region on the portion of the substrate. The method further includes forming a recessed portion of the semiconductor device, the recessed portion extending through the first silicon-based layer and the diffusion region and partially extending into the portion of the substrate. The method additionally includes depositing a second silicon-based layer within the recessed portion. The method further includes etching one or more portions of the second silicon-based layer and the portion of the substrate to form a set of fin structures that include the second silicon-based layer and the portion of the substrate having the dopant and the carbon implanted.