Transistors having semiconductor-metal composite gate electrodes containing different thickness interfacial dielectrics and methods of making thereof

A semiconductor structure comprising:

• a first field effect transistor;
• and
• a second field effect transistor,
• wherein the first field effect transistor comprises:
• a first source region;
• a first drain region;
• a first channel region located between the first source region and the first drain region;
• a first gate dielectric;
• and
• a first composite gate electrode comprising a first vertical stack of a p-doped semiconductor gate electrode, a first interfacial dielectric layer having a first thickness, and a first metallic gate electrode;
• wherein the second field effect transistor comprises:
• a second source region;
• a second drain region;
• a second channel region located between the second source region and the second drain region;
• a second gate dielectric;
• and
• a second composite gate electrode comprising a second vertical stack comprising an n-doped semiconductor gate electrode and a second metallic gate electrode, and either no interfacial dielectric layer located in an interfacial region between the n-doped semiconductor gate electrode and the second metallic gate electrode, or a second interfacial dielectric layer having a second thickness that is less than the first thickness is located in the interfacial region between the n-doped semiconductor gate electrode and the second metallic gate electrode.