Mechanism of current flow and temperature dependence of contact resistivity in Au-Pd-Ti-Pd-n⁺ -GaN ohmic contacts

摘要

We present the results of structural and morphological investigations ofudinteractions between phases in the layers of Au-Pd-Ti-Pd-n⁺-GaN contact metallization that appear at rapid thermal annealing (RTA). It is shown that formation of ohmic contactudoccurs in the course of RTA at Т = 900°C due to formation of titanium nitride. Weudstudied experimentally and explained theoretically the temperature dependence ofudcontact resistivity ρс(Т) of ohmic contacts in the 4.2-380 K temperature range. The ρс(Т)udcurve was shown to flatten out in the 4.2-50 K range. As temperature grew, ρс decreasedudexponentially. The results obtained enabled us to conclude that current flow has fieldudnature at saturation of ρс(Т) and the thermofield nature in the exponential part of ρс(Т)udcurve.