Structures for a field-effect transistor and methods for fabricating a structure for a field-effect transistor. First and second device structure are respectively formed in first and second device regions, and a first dielectric layer is formed over the first and second device regions. The first dielectric layer includes a recess defining a step at a transition between the first and second device regions, and a second dielectric layer is arranged within the recess in the first dielectric layer. A third dielectric layer is arranged over the first dielectric layer in the first device region and over the second dielectric layer in the second device region. A contact, which is coupled with the second device structure, extends through the first, second, and third dielectric layers in the second device region.