Photoelectrochemical conversion in a WO3 coated p-Si photoelectrode: Effect of annealing temperature

The photoelectrochemical properties of a p-type silicon (100) electrode coated with tungsten oxide thin film were investigated as a function of annealing temperature. The variation in the annealing temperature affected the photocurrent of a WO3/p-Si electrode. A maximum photocurrent was obtained when the 500 Å WO3 thin film coated p-Si electrode was annealed at 350 °C for 1 h. A further increase in the annealing temperature and film thickness degraded the photocurrent. This can be explained in terms of electrical resistivity, carrier concentration, and depletion layer width. A WO3 thin film deposition on the p-Si shifted the flatband potential of the p-Si electrode by 0.3 V in the anodic direction, resulting in an improvement in conversion efficiency. These results are supported by x-ray diffraction, Auger electron spectroscopy, and capacitance measurements.