Optimization of atomic layer deposition of Al2O3 films as possible template for graphene transfer

Abstract

Nanofilms of aluminium oxide Al2O3 (ALO) were grown on Si, Cu and graphene/Cu substrates by atomic layer deposition (ALD). Trimethylaluminium (TMA) and deionized (DI) water were used as precursors for the ALD process. In order to obtain the ALD temperature window for the above-mentioned precursors, ALO nanofilms were deposited on Si substrates at temperatures ranging from 50 °C to 300 °C. Based on ellipsometry measurements of the films thickness, the growth rate of ALO films obtained was between 1.15 Å/cycle and 1.25 Å/cycle. Ellipsometry and XPS analyses showed that the optimal growth temperature for ALO films is between 150 °C and 200 °C. A graphene layer was grown on a Cu foil by chemical vapor deposition (CVD) and coated with an ALD ALO nanofilm. Raman spectroscopy was used to characterize the influence of ALO films deposition on the graphene layer. A Raman intensity enhancement for all graphene bands in the Al2O3/graphene/Cu sample was observed.