Applied Science and Convergence Technology 2002; 11(1): 35-42
Published online April 1, 2002
Copyright © The Korean Vacuum Society.
Han-Ki Kim,Kyoung-Kook Kim,Seong-Ju Park,Tae-Yeon Seong,Young Soo Yoon
We fabricate thermally stable and low resistance Ru ohmic contacts to n-ZnO:Al (3×10^(18) ㎝-³), grown by specially designed dual target sputtering system. It is shown that the as-deposited Ru contact produces a specific contact resistance of 2.1×10^(-3) Ω㎠. Annealing of the Ru contacts leads to the improvement of current-voltage characteristics. For example, annealing of the contact at 700℃ for 1 min produces a contact resistance of 3.2×10^(-5) Ω㎠. Furthermore, the metallisation scheme is found to be thermally stable: the surface of the contact is fairly smooth with a rms roughness of 1.4 ㎚ upon annealing at 700℃. These results strongly indicate that the Ru contact represents a suitable metallisation scheme for fabrication of high-performance ZnO-based optical devices and high-temperature devices. In addition, possible mechanisms are suggested to describe the annealing temperature dependence of the specific contact resistance.