A MOSFET has greatly reduced leakage current between the gate electrode and the channel, source and drain regions. The gate electrode materials have lower electron affinities than the channel, source and drain regions. Gate electrode materials with negative electron affinities can also be used. The use of these gate electrode materials enables the band structures of the gate electrode and the other regions to be aligned in a manner that eliminates tunneling states for carriers tunneling between the gate and the body of the device.