The features of contact resistivity of ohmic contacts to n+-GaN AND n+-GaAs at low temperatures

We studied, both theoretically and experimentally, temperature dependences of contact resistivity, ρ_c(T), of ohmic contacts to n⁺-GaN. The ρ_c(T) curves have saturation portion at low temperatures (4.2-50 K) and exponential portion as temperature grows up to 300 K. For comparison we also give the reference data on ρ_c(T) for ohmic contacts to n⁺-GaAs in which the n⁺-regions are obtained by doping the near-contact layer with Ge and Si. Some possible mechanisms are proposed to explain the experimental ρ_c(T) curves for ohmic contacts to n⁺-GaN and n⁺-GaAs.