Gold doping considerably increased the switching speed of NPN silicon transistor.
Gold doping is used to reduce the lifetime of minority carriers. This applies mainly to bipolar semiconductor devices (fast switching diodes).
For MOS-devices gold contamination is extremely unwanted. Gold atoms act as recombination centers and increase leakage currents substantially.
Adding to the colleagues gold wires are used for interconnecting the chip to the legs of the metal frame. Aluminum can be also used for this purpose. They used also in bond wire inductors in radio frequency integrated circuits. As the colleagues pointed out Gold can be used to dope the material as a lifetime killer more for bipolar power devices as fast recovery diodes. However, there is a better method which is electron irradiation. Gold is not normally used in the metal layers of the integrated circuits.
In the metallization of the integrated circuits one uses mostly aluminum and copper.
