1. A semiconductor device, comprising: a semiconductor fin disposed above a substrate, the semiconductor fin comprising a compressively strained semiconductor layer above the substrate and a tensilely strained semiconductor layer on the compressively strained semiconductor layer; a gate structure disposed on a top and along sidewalls of the semiconductor fin, the gate structure comprising a gate electrode disposed on a gate dielectric layer, and the gate structure defining a channel region comprising the compressively strained semiconductor layer and the tensilely strained semiconductor layer of the semiconductor fin; and source and drain regions disposed on either side of the gate structure, adjacent to the channel region.