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

Abstract

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 0.82eV (I–V)/0.98eV (C–V) and 1.34, respectively. However, the BH is increases to 0.87eV (I–V)/1.08eV (C–V) after annealing at 300°C. When the SBD is annealed at 400°C, the BH decreases to 0.74eV (I–V)/0.86eV (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.