  Zero-index (ZI) materials are synthetic optical materials with vanishing
effective permittivity and/or permeability at a given design frequency.
Recently, it has been shown that the permeability of a zero-index host material
can be deterministically tuned by adding photonic dopants. Here, we apply
metal-induced crystallization (MIC) in quasi-random metal-semiconductor
composites to fabricate large-area zero-index materials. Using Ag-Si as a model
systems, we demonstrate that the localized crystallization of the semiconductor
at the metal/semiconductor interface can be used as design parameter to control
light interaction in such a disordered system. The induced crystallization
generates new zero-index states corresponding to a hybridized plasmonic mode
emerging from selective coupling of light to the \r{a}ngstr\"om-sized
crystalline shell of the semiconductor. Photonic doping can be used to enhance
the transmission in these disordered metamaterials as is shown by simulation.
Our results break ground for novel large-area zero-index materials for wafer
scale applications and beyond.
