Phosphorus-hyperdoped Si nanocrystals : a model for localized surface plasmon resonance
Résumé
It has been recently realized that semiconductor nanocrystals can be doped with point defects or impurities up to a very high level, sometimes above the bulk solubility limit. In parallel, hyperdoping has also emerged as a promising means to change the electrical and optical properties of Si. In the present work, we show theoretically that Localized Surface Plasmon Resonance (LSPR) may occur in P-hyperdoped Si nanocrystals, which could greatly contribute to the development of Si based plasmonics [1]. Considering a model system using self-consistent tight binding calculations, we study how the sub-bandgap optical absorption changes with nanocrystal size and doping concentration and we propose a simple model which explains the results. We determine the conditions required to observe LSPR in hyperdoped semiconductor nanocrystals. We explain why the introduction of deep defects in the nanocrystals does not induce LSPR while the introduction of hydrogenic impurities does. [1] X. Pi and C. Delerue, Phys. Rev. Lett. 111, 177402 (2013).