Ti/Ni/Ti/Au Ohmic contact and Schottky transformation to Al-doped ZnO thin films

摘要

A multi-layered Ti (50 nm)/Ni (50 nm)/Ti (50 nm)/Au (50 run) metallic contact to Al-doped ZnO thin films (N_D = 3.64 x 10~(19) cm~(-3)) was reported in this paper. The as-deposited Ti/Ni/Ti/Au scheme showed a specific contact resistivity of 2.07 x 10~(-4) Ω cm~2. And a lowest specific contact resistivity of 6.69 x 10~5 -Ω cm~2 was obtained after annealing at 500°C. The specific contact resistivity showed a decreasing tendency with the annealing temperature up to 500 °C. However, for the sample annealed at above 600 °C, the I-V curves revealed gradual Schottky transformation. Interface diffusions and reactions induced by annealing treatment were found to be responsible for the decrease of Ohmic contact resistivity and the Schottky transformation.