An integrated circuit device includes a substrate having source and drain recesses therein that are lined with respective silicon-germanium liners and filled with doped semiconductor source and drain regions. A stacked plurality of semiconductor channel layers are provided, which are separated vertically from each other within the substrate by corresponding buried insulated gate electrode regions that extend laterally between the silicon-germanium liners. An insulated gate electrode is provided on an uppermost one of the plurality of semiconductor channel layers. The silicon-germanium liners may be doped with carbon.