We report a new metallization process for achieving low resistance ohmic contacts to molecular beam epitaxy grownnhyphen;GaN (sim;1017cmminus;3) using an Al/Ti bilayer metallization scheme. Four different thinhyphen;film contact metallizations were compared during the investigation, including Au, Al, Ti/Au, and Ti/Al layers. The metals were first deposited via conventional electronhyphen;beam evaporation onto the GaN substrate, and then thermally annealed in a temperature range from 500 to 900thinsp;deg;C in a N2ambient using rapid thermal annealing techniques. The lowest value for the specific contact resistivity of 8times;10minus;6OHgr;thinsp;cm2, was obtained using Ti/Al metallization with anneals of 900thinsp;deg;C for 30 s. Xhyphen;ray diffraction and Auger electron spectroscopy depth profile were employed to investigate the metallurgy of contact formation.
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