The present disclosure relates to a method of forming a transistor device having a carbon implantation region that provides for a low variation of voltage threshold, and an associated apparatus. The method is performed by forming a well region within a semiconductor substrate. The semiconductor substrate is selectively etched to form a recess within the well region. After formation of the recess, a carbon implantation is selectively performed to form a carbon implantation region within the semiconductor substrate at a position underlying the recess. An epitaxial growth is then performed to form one or more epitaxial layers within the recess at a position overlying the carbon implantation region. Source and drain regions are subsequently formed within the semiconductor substrate such that a channel region, comprising the one or more epitaxial layers, separates the source/drains from one another.