A method for manufacturing a semiconductor device includes forming a plurality of fins on a semiconductor substrate. In the method, sacrificial spacer layers are formed on the plurality of fins, and portions of the semiconductor substrate located under the sacrificial spacer layers and located at sides of the plurality of fins are removed. Bottom source/drain regions are grown in at least part of an area where the portions of the semiconductor substrate were removed, and sacrificial epitaxial layers are grown on the bottom source/drain regions. The method also includes diffusing dopants from the bottom source/drain regions and the sacrificial epitaxial layers into portions of the semiconductor substrate under the plurality of fins. The sacrificial epitaxial layers are removed, and bottom spacers are formed in at least part of an area where the sacrificial epitaxial layers were removed.