An integrated circuit (IC) structure, an IC device, an IC device assembly, and a method of forming the same. The IC structure includes a transistor device comprising: a channel structure including a semiconductor material; a gate stack including a metal, the gate stack on the channel structure; a source structure in a first trench at a first side of the gate stack; a drain structure in a second trench at a second side of the gate stack; individual ones of the source structure and the drain structure including a source or drain (source/drain) liner comprising a doped epitaxial layer conformal with a surface of a corresponding one of the first trench and the second trench; a fill structure filling a portion of a corresponding one the first trench and the second trench, the fill structure adjacent to and compositionally different from the source/drain liner; and metal contact structures coupled to respective ones of the source structure and the drain structure.