THERMALLY STABLE, LOW-RESISTANCE PDGE-BASED OHMIC CONTACTS TO HIGH-LOW DOPED N-GAAS

Thermally stable, low-resistance PdGe-based ohmic contacts to high-low doped n-GaAs have been developed. The lowest contact resistance obtained is two times lower than that of previously reported PdGe ohmic contacts. The contacts are thermally stable even after isothermal annealing for 5 h at 400 degrees C under atmosphere ambient. X-ray diffraction results and Auger depth profiles show that the good PdGe-based ohmic contact is due to the formation of both AuGa and TiO compounds. The AuGa compound enhances the creation of more Ga vacancies, followed by the incorporation of Ge into Ga vacancies, and the TiO compound suppresses As outdiffusion from the GaAs substrate, respectively. (C) 1995 American Institute of Physics.