Dual threshold voltage (VT) channel devices and their methods of fabrication

Embodiments of the present invention are directed to dual threshold voltage (VT) channel devices and their methods of fabrication. In an example, a semiconductor device includes a gate stack disposed on a substrate, the substrate having a first lattice constant. A source region and a drain region are formed on opposite sides of the gate electrode. A channel region is disposed beneath the gate stack and between the source region and the drain region. The source region is disposed in a first recess having a first depth and the drain region disposed in a second recess having a second depth. The first recess is deeper than the second recess. A semiconductor material having a second lattice constant different than the first lattice constant is disposed in the first recess and the second recess.