Methods are provided for fabricating a semiconductor device. A method comprises forming a layer of a first semiconductor material overlying the bulk substrate and forming a layer of a second semiconductor material overlying the layer of the first semiconductor material. The method further comprises creating a fin pattern mask on the layer of the second semiconductor material and anisotropically etching the layer of the second semiconductor material and the layer of the first semiconductor material using the fin pattern mask as an etch mask. The anisotropic etching results in a fin formed from the second semiconductor material and an exposed region of first semiconductor material underlying the fin. The method further comprises forming an isolation layer in the exposed region of first semiconductor material underlying the fin.