Thermally Stable and Low Resistance Ru Ohmic Contacts to n-ZnO

Abstract

We report on a promising metallisation scheme for high-quality ohmic contacts to n-ZnO:Al (nd=3×1018 cm-3. The as-deposited contact yields a specific contact resistance of 2.1×10-3 Ω·cm2. However, annealing of the contact at 700°C for 1 min results in a resistance of 3.2×10-5 Ω·cm2. The prolonged annealing treatment causes negligible degradation of electrical and thermal properties. These results indicate that the Ru film would be a suitable scheme for the fabrication of high-performance ZnO-based optical and high-temperature devices.