Selective metallization of n-type GaAs formed by projection-patterned excimer laser doping of Si

Resistless microfabrication of the metallization of n-type GaAs formed by projection-patterned doping using a KrF excimer laser is described. Silane (SiH4 ) gas is used as a source material of the n-type dopant of Si. Copper thin films with a linewidth as narrow as 3.4 μm are deposited selectively on the doped region by electroplating using a CuSO4 aqueous solution. Using the selective metallization process, nonalloyed ohmic contacts can be formed with a specific contact resistance of 2.32×10−5 Ω cm2, which is one-thirtieth of that of the conventional alloyed contacts.