OHMIC CONTACTS TO N-TYPE AND P-TYPE GASB

We report the specific contact resistance at zero bias, R(c), and the barrier heights of rapidly thermally alloyed AuGe contacts on 10(17) c m(-3) n-GaSb. An alloying step of 1 min at about 300 degrees C provide s a minimum contact resistance of about 0.4 Omega cm(2). Addition of N i in the form of a AuNiGe process has little effect on R(c), but reduc es the minimum alloying temperature to about 250 degrees C. The furthe r step of an added gold overlayer in the Au/AuNiGe process further red uces the minimum alloying temperature to about 200 degrees C. For cont acts on 10(17) cm(-3) p-GaSb, TiAu proved superior in conductance comp ared to Ti and Cr. Alloying at 300 degrees C slightly improved the qua lity of the contacts. The optimized processes provide compatible bipol ar ohmic metallization for minimum thermal budget.