Study of surface morphology and refractive index of dielectric and metallic films used for the fabrication of monolithically integrated surface plasmon resonance biosensing devices

Integration in a single chip using localized optical phenomena is one of the possible approaches to attain the accuracy, portability and affordability required for future biosensing devices. We address this problem by investigating a grating-coupled quantum well (QW) surface plasmon resonance (SPR) device that comprises a monolithically integrated source of light and a bio-sensitive surface. The successful operation of such a device requires, in addition to the optimization of its architecture, the use of high quality thin films with smooth surface morphology. Here, we present the results of studying a variety of dielectric and Au films intended for the fabrication of QW-SPR devices. For dielectrics, we found that SiO2 films obtained by plasma-enhanced chemical vapor deposition have the best surface morphology and optical properties appropriate for our device. The films of Au fabricated with deposition rates exceeding 0.3 nm/s exhibited relatively smooth surface morphology, however the presence of surface micro-inclusions reduced the attractiveness of such films. To avoid sample overheating that occurs at extremely slow deposition rates, we optimized the fabrication of Au films at 0.05 and 0.2 nm/s.

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► We have investigated fabrication of monolithically integrated SPR biosensing devices.
► PECVD offers SiO2 films of superior optical properties.
► The Au films by e-beam at deposition rates not exceeding 0.3 nm/s are desirable.
► Deposition at 0.5 nm/s allows avoiding the excessive heating of photoresists.