Polarization-resolved plasmon-modulated emissions of quantum dots coupled to aluminum dimers with sub-20 nm gaps

• Main Authors: Zhang, Dao Hua, Fong, Kah Ee, Gao, Yuan, Dang, Cuong, Tobing, Landobasa Yosef Mario, Muhammad Danang Birowosuto, Demir, Hilmi Volkan
• Other Authors: School of Electrical and Electronic Engineering
• Format: Article
• Language: English
• Published: 2019
• Subjects: DRNTU::Engineering::Electrical and electronic engineering; Plasmonic Enhancement; Aluminum Plasmonics
• Online Access: https://hdl.handle.net/10356/88946; http://hdl.handle.net/10220/48344
• Institution: Nanyang Technological University

An aluminum dimer nanoantenna with nanogaps is an ideal platform for enhancing light–matter interaction at the nanoscale for the UV–vis spectrum, but its realization has been hindered by the surface oxidation of aluminum nanostructures, aluminum interband loss, and practical limitations in lithographic patterning. Here, we have overcome these problems and demonstrated the successful fabrication of an aluminum dimer antenna with a ∼10 nm gap, which to the best of our knowledge marks the smallest features of an Al nanoantenna. We present the first in-depth study of strongly polarization-dependent emissions of colloidal quantum dots coupled with Al dimers and elucidate the individual contributions of the excitation intensity, quantum yield, and extraction efficiency enhancements from numerical and experimental perspectives. We estimate the Purcell effect corresponding to a single Al-dimer antenna as ∼104 by taking into account the ensemble averaging effect and the distributions in emitter dipole orientations. This finding brings us a step closer toward a cost-effective realization of bright and ultrafast single emitters.