A common contact to both n and p Ga-based antimonide materials has been developed for serial wiring of quaternary monolithic interconnected module thermophotovoltaic devices. The contact consists of a multilayer stack of Pd/Ge/Au/Ti/Au. Circular transmission line model measurements yield a specific contact resistance as low as 10(-5) Omega cm(2) for contacts to n-GaSb and 10(-4) Omega cm(2) for contacts to p-GaSb without annealing. Further reduction in specific contact resistance can be obtained for contacts annealed in nitrogen ambient for 10 s at 250-300degrees C. Cell isolation and thermophotovoltaic diodes fabricated using the five-layer metallization for both the p- and n-type contact exhibit current-voltage characteristics equivalent to diodes formed using multilayer metallization for the n-type contact and standard Ti/Au for the p- contact. While annealing improves contact properties, excessive annealing can lead to diffusion of the metallization into the semiconductor and lead to device degradation.