A method of forming a semiconductor device includes providing a semiconductor structure that includes a first semiconductor material extending from a first region to a second region. The method further includes removing a portion of the first semiconductor material in the second region to form a recess, where the recess exposes a sidewall of the first semiconductor material disposed in the first region; forming a dielectric material covering the sidewall; while the dielectric material covers the sidewall, epitaxially growing a second semiconductor material in the second region adjacent the dielectric material; and forming a first fin including the first semiconductor material and a second fin including the second semiconductor material.