Low resistance Pd/Zn/Pd ohmic contact to p-In(0.82)Ga0.18As(0.39)P(0.61)

We report on the investigation of a low resistance Pd/Zn/Pd contact to p-InGaAsP (lambda = 1.14 mu m). The contact had a minimum contact resistivity of similar to 3 x 10(-7) Ohm cm(2) to the substrate doped to 2 x 10(18) cm(-3). The samples showed rather uniform surface and interfacial morphologies. X-ray studies showed the formation of a PdZn phase for samples annealed below 400 degrees C and this phase started to decompose at temperatures higher than 400 degrees C. Pd-III compounds (Pd2Ga5 and PdIn3) also started to form for annealing temperatures higher than 400 degrees C. The ohmic behavior can be understood in terms of the decomposition of the PdZn phase and the formation of Pd-III compounds for samples annealed at 400 degrees C or higher. The thermal stability of this contact at 400 degrees C was found to be stable, which is important for device applications. (C) 1997 American Institute of Physics.