A method comprises forming a first semiconductor device in a substrate, where the first semiconductor device comprises a gate structure, a spacer disposed on sidewalls of the gate structure, the spacer having a first thickness, and raised source and drain regions disposed on either side of the gate structure. The method further comprises forming a second semiconductor device in the substrate and electrically isolated from the first semiconductor device, where the second semiconductor device comprises a gate structure, a spacer disposed on sidewalls of the gate structure, the spacer having a second thickness less than the first thickness of the spacer of the first semiconductor device, and recessed source and drain regions disposed on either side of the gate structure.