Transfer Matrix Modeling Optical Properties of Short-Period Aluminum Oxide-Copper Multi-Layered Nanocomposites

The goal of this study is to use the transfer matrix method to analyze the reflectance of light shined onto thin film layers. The thin film layers were generated by applying Sputtering Atomic Layer Augmented Deposition (SALAD) to create thin aluminum oxide and copper films. SALAD combines atomic layer deposition (ALD) techniques, providing precise film thickness control. The study then utilizes the transfer matrix method to analyze the reflectance, aiming to gain insight into the interactions between light and the constituent materials. The researchers generated samples consisting of 300 layers of AlOx and Cu, which were then analyzed using spectroscopic ellipsometry. To calculate the reflectance, distinct functions were developed in MatLab to represent the equations for transmission matrices and propagation matrices. To evaluate the approach, four pairs of HfO2-SiO2 thin film layers were simulated, with their refractive indices derived from Sellmeier’s equations, which appeared to be very successful. Although the simulation successfully predicted reflectance for the HfO2-SiO2 layers, the calculations with the Transfer Matrix Method had deviations compared to the laboratory results obtained for the more complex AlOx-Cu samples. To better understand the deviations, polynomial functions were used to model these differences which yield a pattern. suggesting that factors like unaccounted plasmonics and layer imperfections may be at play. This study lays a foundation for research to refine models and explore quantum effects that influence these advanced materials.