Photothermal energy conversion in plasmonic nanoantennas as a new path for the local growth of ZnO in nanophotonic devices

In this work, we explore a new bottom-up approach based on plasmon-assisted hydrothermal synthesis (PAHS) to achieve localized growth of zinc oxide (ZnO) in hybrid nanophotonic devices. By engineering gold nanogap antennas, we achieve efficient control over the localization and enhancement of both the electric field and the generated heat. A nanobutterfly antenna is designed to achieve both polarization-dependent heat localization and localized electric field enhancement. A few-nm-thick ZnO layer is grown at the targeted location of the nanogap antenna thanks to selective plasmonic heating. We also numerically study the back-action induced by the material synthesis on the heat generated by the antenna and show how PAHS can be used as a self-limited growth method. The PAHS method opens new perspectives for the design and fabrication of hybrid nanophotonic devices.