A semiconductor device includes a plurality of stacked structures spaced apart from each other on a substrate, wherein the plurality of stacked structures each comprise a plurality of gate layers and a plurality of channel layers, a plurality of arsenic implanted regions on portions of a surface of the substrate adjacent the plurality of stacked structures, and a plurality of epitaxial source/drain regions extending from the plurality of stacked structures, wherein the plurality of epitaxial source/drain regions are spaced apart from the plurality of arsenic implanted regions.