The exceptional electrical and mechanical properties of graphene make it a leading candidate for advanced electronic and sensing applications; however, its integration into functional devices often requires high- \(\kappa \) dielectric layers, such as aluminum oxide ( \(\hbox {Al}_2\hbox {O}_{3}\) ). Atomic layer deposition (ALD) is a promising technique for growing such dielectric films due to the excellent thickness control and good uniformity that can be achieved. Despite these benefits, ALD-based \(\hbox {Al}_2\hbox {O}_{3}\) deposition on graphene can unintentionally degrade the quality of the graphene by introducing strain, doping, or defects during the deposition process. Understanding how these effects vary with the early-stage thickness of the dielectric layer is essential for optimizing device performance. This study presents a systematic investigation of the structural modification induced in monolayer graphene as a function of ALD-deposited \(\hbox {Al}_2\hbox {O}_{3}\) dielectric thickness. A mechanically exfoliated single-layer graphene sample was transferred onto Si/ \(\hbox {SiO}_{2}\) substrates and subsequently coated with \(\hbox {Al}_{2}\hbox {O}_{3}\) films of varying thicknesses. \(\hbox {Al}_{2}\hbox {O}_{3}\) deposition was carried out via direct \(\hbox {H}_2\hbox {O}\) -based ALD at 120°C, without any surface pretreatment, to avoid initial damage to the graphene prior to the start of \(\hbox {Al}_{2}\hbox {O}_{3}\) deposition. Damage to graphene during the deposition process was analyzed by varying the film thickness of \(\hbox {Al}_{2}\hbox {O}_{3}\) , and Raman spectroscopy performed at each stage of sample preparation made it possible to evaluate the impact of the \(\hbox {Al}_{2}\hbox {O}_{3}\) coating on the graphene layer. This work reveals that defect, strain, and doping dynamics at the Si/ \(\hbox {SiO}_{2}\) / \(\hbox {Al}_{2}\hbox {O}_{3}\) /graphene interface are strongly influenced by early-stage dielectric thickness, offering an effective strategy to minimize damage and preserve graphene’s intrinsic properties—an essential step toward the development of high-performance graphene-based electronic devices.
