Embodiments disclosed herein include nanowire and nanoribbon devices with non-uniform dielectric thicknesses. In an embodiment, the semiconductor device comprises a substrate and a plurality of first semiconductor layers in a vertical stack over the substrate. The first semiconductor layers may have a first spacing. In an embodiment, a first dielectric surrounds each of the first semiconductor layers, and the first dielectric has a first thickness. The semiconductor device may further comprise a plurality of second semiconductor layers in a vertical stack over the substrate, where the second semiconductor layers have a second spacing that is greater than the first spacing. In an embodiment a second dielectric surrounds each of the second semiconductor layers, and the second dielectric has a second thickness that is greater than the first thickness.