Thin-Film SUEX as an Antireflection Coating for mmW and THz Applications

We present a simple process for depositing SUEX dry films to realize effective antireflection coatings on high-resistivity silicon wafers and lenses. Heat-assisted conformal deposition of SUEX film followed by curing via ultraviolet exposure achieves robust adhesion to the silicon lens surface. Due to its relatively low material loss and commensurate refractive index, quarter-wavelength-thick SUEX coatings minimize reflection losses and significantly improve signal coupling into high-index silicon lenses. As an example, a 150-μm-thick SUEX layer was conformally coated on a 1-cm-diameter high-resistivity silicon lens to reduce reflection loss to less than 4% over the 220-325 GHz band.