Role of local fields in the optical properties of silicon nanocrystals using the tight binding approach

TL;DR

This paper investigates how local electromagnetic fields influence the optical properties of silicon nanocrystals, revealing significant modifications due to surface effects and validating classical models even at small scales.

Contribution

It demonstrates the importance of local field effects in silicon nanocrystals and shows that classical dielectric models are applicable across a range of sizes, including very small nanocrystals.

Findings

Local fields dramatically modify optical response

Classical dielectric model agrees with tight binding results

Size dependence of optical properties discussed

Abstract

The role of local fields in the optical response of silicon nanocrystals is analyzed using a tight binding approach. Our calculations show that, at variance with bulk silicon, local field effects dramatically modify the silicon nanocrystal optical response. An explanation is given in terms of surface electronic polarization and confirmed by the fair agreement between the tight binding results and that of a classical dielectric model. From such a comparison, it emerges that the classical model works not only for large but also for very small nanocrystals. Moreover, the dependence on size of the optical response is discussed, in particular treating the limit of large size nanocrystals.