A method of manufacturing a semiconductor device, a semiconductor device and systems incorporating the same include transistors having a gate metal doped with impurities. An altered work function of the transistor may alter a threshold voltage of the transistor. In certain embodiments, a gate metal of a first MOSFET is doped with impurities. A gate metal of a second MOSFET may be left undoped, doped with the same impurities with a different concentration, and/or doped with different impurities. In some embodiments, the MOSFETs are FinFETs, and the doping may be a conformal doping.