A semiconductor device includes a first stack of nanowires above a substrate with a first gate structure over, around, and between the first stack of nanowires and a second stack of nanowires above the substrate with a second gate structure over, around, and between the second stack of nanowires. The device also includes a first source/drain region contacting a first number of nanowires of the first nanowire stack and a second source/drain region contacting a second number of nanowires of the second nanowire stack such that the first number and second number of contacted nanowires are different.