Optically absorbing trilayer films fabricated using a filtered cathodic vacuum Arc

A Filtered Cathodic Vacuum Arc (FCVA) deposition system has been used to produce Al2O3/Al/Al2O3 trilayers for use as optically absorbing coatings. Ellipsometry was used to measure the optical constants of the AlOx films and X-ray photoelectron spectroscopy (XPS) was used to measure their stoichiometry. It was found that a wide range of Ar/O2 inlet flow-rates could be used to produce stoichiometric Al2O3 in the FCVA system. Several Al2O3/Al/Al2O3 tri-layers have been produced with different Al layer thicknesses and the simulated and experimental reflection characteristics have been compared. An average reflectance of 4% was achieved over the visible spectrum for the optimised trilayer coating deposited on silicon.