Enhancement in the solar light harvesting ability of tungsten oxide thin films by annealing in vacuum and hydrogen

Thin films of tungsten oxide were fabricated by RF-sputtering. The films were annealed in vacuum and hydrogen at different temperatures to enhance the solar light absorption in the visible and near infrared regions by creating oxygen vacancies and localized surface plasmon resonance. The effect of vacuum and hydrogen annealing on structural, morphology, chemical, electrical and optical properties were investigated. Vacuum-annealed and hydrogen-annealed films behaved like degenerate semiconductor and showed strong absorption in the near-infrared region due to localized surface plasmon resonance. The solar light harvesting properties of as-deposited, vacuum-annealed and hydrogen-annealed tungsten oxide films were examined by measuring their photocurrent response.