Methods of forming a field-effect transistor and structures for a field-effect transistor. A gate structure is formed that overlaps with a channel region in a semiconductor fin. The semiconductor fin is etched with a first etching process to form a first cavity extending into the semiconductor fin adjacent to the channel region. The semiconductor fin is etched with a second etching process to form a second cavity that is volumetrically smaller than the first cavity and that adjoins the first cavity.