Electrical and structural properties of tungsten Schottky contacts to p-type InP at different annealing temperatures

The electrical and structural properties of a fabricated W/p-InP Schottky barrier diode (SBD) have been investigated as a function of annealing temperature. The W/p-InP SBD exhibits good rectification behavior. The barrier height (BH) and ideality factor of the W/p-InP SBD are determined to be 0.82 eV (I-V)/0.98 eV (C-V) and 1.34, respectively. However, the BH is increases to 0.87 eV (I-V)/1.08 eV (C-V) after annealing at 300 °C. When the SBD is annealed at 400°C, the BH decreases to 0.74 eV (I-V)/0.86 eV (C-V) and the ideality factor increases to 1.45. Results indicate that a maximum BH is obtained on the W/p-InP SBD at 300°C. Norde method is also employed to determine BHs of W/p-InP SBD which are in good agreement with those estimated by the I-V method. Further, Cheung method is used to estimate the series resistance of the W/p-InP SBD, and the consistency is checked using the Norde method. Besides, the energy distribution of interface state density is determined from the forward bias I-V data at different annealing temperatures. Auger electron spectroscopy and X-ray diffraction studies revealed that the formation of W-P interfacial phases at the W/p-InP interface may be the cause for the increase of BH upon annealing at 300°C. AFM results indicated that the overall surface morphology of the W/p-InP SBD did not change significantly at elevated temperatures.