A study of thin film encapsulation on polymer substrate using low temperature hybrid ZnO/Al2O3 layers atomic layer deposition

Hybrid ZnO/Al2O3 layers grown by atomic layer deposition (ALD) at extremely low temperature (60 °C) have been investigated as thin film encapsulations (crystalline ZnO and amorphous Al2O3 films) on polymer substrates. All single and laminated film thicknesses are approximately 60 nm. As the thickness of ZnO layer decreased from 60 nm to 0 nm, the physical properties of laminated structures were systematically manipulated such as film crystallinity, surface roughness, density, transmittance and stress. The multi-laminated structure with 10 nm thick ZnO and 10 nm thick Al2O3 layers exhibited very lower crystallinity, smoother surface (root mean square ∼ 0.2 nm), higher transmittance (over 90% at 550 nm wavelength) and similar film stress, to compare with these of a single ZnO film. As a transparent gas barrier layer, the multi-laminated structure with a thinner ZnO and Al2O3 had better barrier property than that of single ZnO and Al2O3 layers, showing that the water vapor transmission ratio of multi-laminated ZnO/Al2O3 layer was 10 times lower than that of the single layer.