Near-Room-Temperature Plasma and UV-Assisted Atomic Layer Deposited Al2O3@Graphene Composite for Efficient and Flexible Encapsulation

High-density, low-defect thin films with low water vapor transmission rates (WVTR) are essential for next-generation display encapsulation. In this study, flexible thin-film/graphene composite encapsulation layers were fabricated on PET substrates by energy-enhanced atomic layer deposition (ALD) at low temperature. Here, we compared the physical, chemical, and mechanical properties of ALD Al2O3/graphene membranes fabricated by three different ALD methods: thermal (T-ALD), plasma-enhanced (PEALD), and UV-assisted (UVALD). T-ALD produced low-density films with moisture-permeable pathways, resulting in higher WVTR. PEALD yielded denser films with improved adhesion but caused partial damage to graphene, which increased WVTR. UVALD produced dense films while minimizing graphene damage, achieving the lowest WVTR. After bending test, T-ALD showed an increased WVTR due to poor adhesion, whereas PEALD maintained stable performance. UVALD showed crack formation after bending, leading to an increased WVTR. Each ALD process offers distinct advantages, suggesting its potential for flexible electronic encapsulation.