Methods according to the present disclosure include: providing a substrate including: a first semiconductor region, a second semiconductor region, and a trench isolation (TI) laterally between the first and second semiconductor regions; forming an epitaxial layer on at least the first semiconductor region of the substrate, wherein the epitaxial layer includes a first semiconductor base material positioned above the first semiconductor region of the substrate; forming an insulator region on at least the first semiconductor base material, the trench isolation (TI), and the second semiconductor region; forming a first opening in the insulator over the second semiconductor region; and growing a second semiconductor base material in the first opening, wherein a height of the second semiconductor base material above the substrate is greater than a height of the first semiconductor base material above the substrate.