Effect of Al-doped ZnO film thickness on periodic GaAs subwavelength grating structures for photovoltaic device applications

We investigated the effect of Al-doped zinc oxide (AZO) films with different thicknesses deposited onto periodic cone-shaped GaAs subwavelength grating (SWG) structures on their physical properties. As the AZO deposition time was increased, the surface morphology of AZO deposited GaAs SWGs was changed. These structures exhibited the surface reflection of <∼6.8% at 300–1200 nm because of their effective graded index distribution between air and the GaAs substrate via the AZO deposited GaAs SWGs, producing a lowest average reflectance of ∼2.1% at 40 min of deposition time. With increasing the deposition time, the crystallinity of the AZO films deposited on GaAs SWGs was enhanced, which leaded to the decrease of the effective resistivity up to ∼1.55 × 10−3 Ω-cm at 100 min. The wetting behavior of a water droplet on the surface of samples was also studied.