RF-sputtered CrB2 diffusion barrier for Ni/Au Ohmic contacts on p-CuCrO2

Ohmic contacts to p-type CuCrO2 using Ni/Au/CrB2/Ti/Au contact metallurgy are reported. The samples were annealed in the 200-700 °C range for 60 s in flowing oxygen ambient. A minimum specific contact resistance of ∼2 × 10−5 Ω cm2 was obtained after annealing at 400 °C. Further increase in the annealing temperature (>400 °C) resulted in the degradation of contact resistance. Auger Electron Spectroscopy (AES) depth profiling showed that out-diffusion of Ti to the surface of the contact stacks was evident by 400 °C, followed by Cr at higher temperature. The CrB2 diffusion barrier decreases the specific contact resistance by almost two orders of magnitude relative to Ni/Au alone.