ABSTRACT
The electrical properties were compared for near-noble transition-metalbased ohmic contacts with a M/Zn/M (M= Ni, Pd) sandwiched structure prepared on p-type InP. The minimum contact resistivities of ~7 × 10-5 Ωcm2 were obtained in both the NiZn and PdZn contacts, while the process window for annealing time of the PdZn contacts was much wider than that of the NiZn contacts. From X-ray diffraction and cross-sectional electron microscopic study at the metal/InP interfaces, it was found that ternary compounds such as Ni2.7InP and Pd;>InP were formed at the Ni/InP and Pd/InP interfaces, respectively. However, the Ni2.7InP compounds were not stable at annealing temperatures above 300°C, which is the primary reason of poor thermal stability of the NiZn contacts, while the PddnP compound was stable at such high temperatures. Selection of a suitable base-metal for InP ohmic contacts was also discussed.
