Plasma-induced surface textures of ZnO:Al transparent conductive films

• Ar/H2 plasma treatments with various pressure are used to texture AZO films.
• Best conductivity (ρ = 4.88 × 10−4 Ω cm, n = 8.87 × 1020 cm−3) are obtained.
• H donors will passivate defects, thus improving the total properties.
• The optical scattering is increased to 1.68% by the ∼200 nm pit size.
• A best haze value of 2.00% at 550 nm is obtained at 50 Pa.

Post Ar/H2 plasma etching method is used to fabricate the texture surface of RF-sputtered ZnO:Al (AZO) transparent conductive films. Different plasma pressures (50 Pa, 100 Pa, 150 Pa and 200 Pa) are adopted during the etching process. The crystallinity improves with increasing the plasma pressure to 150 Pa. Surface morphology varies substantially by the bombardment of high energy Ar and H plasma atoms. Reduction of the mean free path of the plasma atoms and increment of the effective plasma atoms at high pressure will lead to the reduction of RMS after reaching to the largest value of 10.3 nm at 50 Pa. Lowest resistivity of 4.88 × 10−4 Ω cm and largest carrier concentration of 8.87 × 1020 cm−3 are obtained at 50 Pa due to the incorporation of hydrogen donors (passivation defects and grain boundary). The enhanced optical scattering ability by the texture structure (a pit size of ∼200 nm) results in a largest diffuse transmittance value of 1.68% and a best haze value of 2.00% at 550 nm at 50 Pa.