In an embodiment, a device includes: a fin extending from a substrate; a gate stack over a channel region of the fin; and a source/drain region in the fin adjacent the channel region, the source/drain region including: a first epitaxial layer contacting sidewalls of the fin, the first epitaxial layer including silicon and germanium doped with a dopant, the first epitaxial layer having a first concentration of the dopant; and a second epitaxial layer on the first epitaxial layer, the second epitaxial layer including silicon and germanium doped with the dopant, the second epitaxial layer having a second concentration of the dopant, the second concentration being greater than the first concentration, the first epitaxial layer and the second epitaxial layer having a same germanium concentration.