The present disclosure provides a FinFET device. The FinFET device comprises a semiconductor substrate of a first semiconductor material; a fin structure of the first semiconductor material overlying the semiconductor substrate, wherein the fin structure has a top surface of a first crystal plane orientation; a diamond-like shape structure of a second semiconductor material disposed over the top surface of the fin structure, wherein the diamond-like shape structure has at least one surface of a second crystal plane orientation; a gate structure disposed over the diamond-like shape structure, wherein the gate structure separates a source region and a drain region; and a channel region defined in the diamond-like shape structure between the source and drain regions.