Electrical characteristics and thermal stability of ohmic contacts to p-type In0.47Ga0.53/As/InP

Abstract

The electrical characteristics and thermal stability of Pd/Zn/Pd/Au, Pd/Au, Zn/Pd/Au, Au/Zn/Au, Ni/Zn/Ni/Au, and Pd/Mn/Sb/Pd/Au contacts to p-type In0.47Ga0.53As/InP have been investigated. For all of the as-deposited contacts, the specific contact resistance, ρc, was within the range between 1 and 3×10−5 Ω cm2. The thermal annealing of the contacts between 250 and 500 °C produced a differing effect on ρc for each of the metallization schemes. Based on ρc measurements, the thermal stability of the contacts at 400 °C showed an initial regime of low degradation rate with a subsequent transition to a higher rate regime. The exception to this trend was the Pd/Mn/Sb/Pd/Au contact for which no threshold was evident, and for which the dependence of degradation rate on time, t0.15, was lower than for the other configurations with t0.5. During aging at 500 °C, a single regime of high degradation rate was present. In both the low rate and high rate regimes, the type of interfacial metal was not a significant factor in determining the dependence of degradation rate on time.