Influence of annealing on structural and electrical properties of double metal structure Ru/Cu contacts on n-type InP

In this article, we have investigated the effects of rapid thermal annealing on the electrical and structural properties of Ru/Cu Schottky contacts on n-InP by current density-voltage (J-V), capacitance-voltage (C-V), Secondary ion mass spectrometer (SIMS) and X-ray diffraction (XRD) measurements. The Schottky barrier height (SBH) of the as-deposited Ru/Cu Schottky contact is found to be 0.65 _eV (I-V) and 0.84 _eV (C-V), respectively. The obtained barrier height values 0.81 eV (I-V), 0.95 _eV (C-V) at 100°C, 0.85 _eV (I-V), 1.02 _eV (C-V) at 200°C, 0.80 _eV (I-V), 0.90 _eV (C-V) at 300°C and 0.75 _eV (I-V), 0.88 _eV (C-V) at 400°C. It is observed that the SBH increases with annealing temperature up to 200°C. Further, increase in the annealing temperature up to 400°C, SBH decreases compared to the one at 200°C annealed samples. Norde method is also used to calculate the barrier height of Ru/Cu Schottky contact. Based on the above results, the optimum annealing temperature for the Ru/Cu Schottky contact is 200°C. According to SIMS and XRD results, the formation of indium phases at the interface may be the reason for the increase of barrier height after annealing at 200°C. The AFM results showed that the overall surface morphology of Ru/Cu Schottky contact is fairly smooth even after annealing at 400°C.