In one embodiment, the second metal gate electrode 137 is a metal having a mid-gap work function of between around 4.4 to around 4.8 eV, such as TiN. In alternative embodiments, the second metal gate electrode 137 is an n-type metal and has a work function of around 3.9 eV to around 4.4 eV. N-type metals include, for example, Ti, Al and TiAl.