The present disclosure provides an embodiment of a fin-like field-effect transistor (FinFET) device. The device includes a plurality of first fin structures over a substrate. The first fin structure includes a first semiconductor material layer, a second semiconductor material layer disposed over the first semiconductor material layer, being at least partially surrounded by a semiconductor oxide feature. The device also includes a third semiconductor material layer disposed over the second semiconductor material layer and a second fin structures over the substrate and adjacent to one of the first fin structures. The second fin structure includes the first semiconductor material layer and the third semiconductor material layer disposed over the dielectric layer.