Impact of Annealing Temperature on Thermal Stability of H-Al Co-Doped Zinc Oxide Coatings

The hydrogen and aluminum co-doped zinc oxide (H-AZO) thin films were deposited by DC magnetron sputtering at low temperature.The influence of the annealing temperature in low vacuum on the thermal stability of electrical and optical properties was investigated with X-ray diffraction, spectrophotometry and Hall-effect measurement.The results show that annealing at a temperature over 300℃ negatively affected the thermal stability of H-AZO coatings.For example, as the annealing temperature increased from 300℃ up to 400℃, the electrical resistivity significantly increased from 4.7×10^-4 to 1.43×10^-3Ω·cm, accompanied by a reduction of the optical band gap, possibly because of increasing escape of hydrogen in the H-AZO coatings.We suggest that the H-AZO coatings, annealed at 300℃, be a good transparent conducting oxide layer for thin film solar cells.