Effect of annealing temperature on the electrical, structural and surface morphological properties of Ru/Ti Schottky contacts on n-type InP

• Effects of annealing on electrical and structural properties of Ru/Ti/n-InP SBD are studied.
• High barrier height is obtained on as-deposited Ru/Ti/n-InP SBD.
• Interface state density increases with increasing annealing temperature.
• Decrease in BH may be due to formation of phosphorous phases at the interface upon annealing.
• Overall surface morphology of the SBD did not change significantly upon annealing.

The effects of annealing temperature on the electrical, structural and surface morphological properties of Ru/Ti/n-InP Schottky diode have been investigated. Calculations showed that the Schottky barrier height (SBH) and ideality factor n of the as-deposited Ru/Ti/n-InP Schottky diode are 0.82 eV (I–V)/1.00 eV (C–V) and 1.19, respectively. However, it is observed that the SBH of Ru/Ti/n-InP Schottky diode decreases upon annealing at 200 °C, 300 °C and 400 °C. Cheung’s and Norde method are also employed to calculate the SBH, ideality factor and series resistance of the Ru/Ti/n-InP Schottky diode as a function of annealing temperature. Experimental results reveal that the SBH and series resistance of the Ru/Ti/n-InP Schottky diode decreases upon annealing temperatures. The energy distribution of interface state density (Nss) is determined for the Ru/Ti/n-InP Schottky diode at different annealing temperatures. The X-ray diffraction studies revealed that the formation of phosphide phases at the Ru/Ti/n-InP interface may be the cause for the decrease of SBH upon annealing temperature. The AFM results indicated that there is no significant degradation in the surface morphology of the Ru/Ti Schottky contacts at elevated annealing temperatures.