Semiconductor-like optical properties unveiled by dispersion relation modeling of short-period aluminum oxide-copper multi-layered nanocomposites deposited by sputtering atomic layer augmented deposition (SALAD)

In our previous publication, we discussed the optical properties of short-period multi-layered nanocomposites consisting of 300 pairs of an AlOx layer and a Cu layer produced from sputtering atomic layer augmented deposition (SALAD). These samples displayed unusual spectral reflectance that could not be well described via conventional means and could not be explained as an interpolation of the constituent materials, which is most likely due to the fact that the samples optically behave as a homogeneous composite rather than a multi-layered structure. Thus, in the present study, dispersion relation modeling (DRM) is used to extract fundamental optical constants – refractive index – to assess distinctive optical properties of the samples. While the DRM model implemented proved to be imperfect with regard to purely non-holomorphic materials, preliminary results nevertheless predicts that the samples – composed of multiple layers of metal and dielectric – should display semiconductor-like optical behavior, therefore, indicating SALAD can potentially yield materials, by combining metal and dielectric, that virtually behave as semiconductors.