A multi-gate device is disclosed. In one aspect, the device includes a substrate having a first semiconductor layer of a first carrier mobility enhancing parameter, a buried insulating layer, and a second semiconductor layer with a second carrier mobility enhancing parameter. The device also includes a first active region electrically isolated from a second active region in the substrate. The first active region has a first fin grown on the first semiconductor layer and having the first mobility enhancing parameter. The second active region has a second fin grown on the second semiconductor layer and having the second mobility enhancing parameter. The device also includes a dielectric layer over the second semiconductor layer which is located between the first fin and the second fin. The first and second fins protrude through and above the dielectric layer.