Junction field-effect transistors and design structures for a junction field-effect transistor. A source and a drain of the junction field-effect transistor are comprised of a semiconductor material grown by selective epitaxy and in direct contact with a top surface of a semiconductor layer. A gate is formed that is aligned with a channel laterally disposed in the semiconductor layer between the source and the drain. The source, the drain, and the semiconductor layer are each comprised of a second semiconductor material having an opposite conductivity type from a first semiconductor material comprising the gate.