A first channel structure includes SixGe1-x and a second channel structure includes a group III-V compound material. First and second gate stacks are formed on the first and second channel structures. An insulating layer is formed on the gate stacks and the channel structures and is removed from the first channel structure to form a spacer on sidewalls of the first gate stack. First raised source and drain layers are formed on the first channel structure. The insulating layer is removed from the second channel structure to form a spacer on sidewalls of the second gate stack. The surfaces of the first and second channel structures and first source and drain layers are oxidized. The oxide layers are treated by a cleaning process that selectively removes the second native oxide layer only. Second raised source and drain layers are formed on the second channel structure. A CMOS structure is disclosed.