Structural, electrical, and surface morphological characteristics of rapidly annealed Pt/Ti Schottky contacts to n-type InP

We have investigated the electrical and structural properties of Pt/Ti metallization scheme on n-type InP as a function of annealing temperature using current-voltage (I-V), capacitance-voltage (C-V), Auger electron spectroscopy (AES), and X-ray diffraction (XRD) measurements. Measurements showed that barrier height of as-deposited Pt/Ti Schottky contact is 0.62 eV (I-V) and 0.76 eV (C-V). Experimental results indicate that high-quality Schottky contact with barrier height and ideality factor of 0.66 eV (I-V), 0.80 eV (C-V), and 1.14 can be achieved after annealing at 400°C for 1 min in N ₂ atmosphere. Further, it is observed that the barrier height slightly decreases to 0.55 eV (I-V) and 0.71 eV (C-V) after annealing at 500°C. Norde method is also employed to calculate the barrier height of Pt/Ti Schottky contacts. The obtained values are in good agreement with those obtained by I-V measurements. These results indicate that the optimum annealing temperature for the Pt/Ti Schottky contact is 400°C. According to AES and XRD analysis, the formation of indium phases at the Pt/Ti/n-InP interface could be the reason for the increase of Schottky barrier height (SBH) after annealing at 400°C. Results also showed the formation of phosphide phases at the interface. This may be the reason for the decrease in the barrier height after annealing at 500°C. The AFM results showed that the overall surface morphology of Pt/Ti Schottky contact is reasonably smooth.