Semiconductor devices are provided. A semiconductor device includes a substrate. The semiconductor device includes an isolation layer defining active portions of the substrate that are spaced apart from each other in a direction. The semiconductor device includes an epitaxial layer on the active portions. The semiconductor device includes a metal silicide layer on the epitaxial layer. Moreover, the semiconductor device includes a contact structure that only partially overlaps the metal silicide layer on the epitaxial layer. Related methods of forming semiconductor devices are also provided.