We report a new metallization process for achieving low resistance ohm
ic contacts to molecular beam epitaxy grown n-GaN (approximately 10(17
) CM-3) using an Al/Ti bilayer metallization scheme. Four different th
in-film contact metallizations were compared during the investigation,
including Au, Al, Ti/Au, and Ti/Al layers. The metals were first depo
sited via conventional electron-beam evaporation onto the GaN substrat
e, and then thermally annealed in a temperature range from 500 to 900-
degrees-C in a N2 ambient using rapid thermal annealing techniques. Th
e lowest value for the specific contact resistivity of 8X10(-6) OMEGA
CM2, was obtained using Ti/Al metallization with anneals of 900-degree
s-C for 30 s. X-ray diffraction and Auger electron spectroscopy depth
profile were employed to investigate the metallurgy of contact formati
on.