In an embodiment, a device includes: a nanostructure; and a source/drain region adjoining a channel region of the nanostructure, the source/drain region including: a first epitaxial layer on a sidewall of the nanostructure, the first epitaxial layer including a germanium-free semiconductor material and a p-type dopant; a second epitaxial layer on the first epitaxial layer, the second epitaxial layer including a germanium-containing semiconductor material and the p-type dopant; and a third epitaxial layer on the second epitaxial layer, the third epitaxial layer including the germanium-containing semiconductor material and the p-type dopant.