Embodiments of the present invention are directed to methods and resulting structures for nanosheet devices having defect free channels. In a non-limiting embodiment of the invention, a nanosheet stack is formed over a substrate. The nanosheet stack includes alternating first sacrificial layers and second sacrificial layers. One layer of the first sacrificial layers has a greater thickness than the remaining first sacrificial layers. The first sacrificial layers are removed and semiconductor layers are formed on surfaces of the second sacrificial layers. The semiconductor layers include a first set and a second set of semiconductor layers. The second sacrificial layers are removed and an isolation dielectric is formed between the first set and the second set of semiconductor layers.