Electromagnetic Field Resonance in Semiconductor Nanocrystals

Abstract

We model the inhomogeneous dielectric permittivity of a semiconductor nanocrystal by considering a dielectric sphere with a core and a concentric spherical shell of different permittivities. We show that the penetration of the electric field is resonantly enhanced when the laser frequency approaches an electromagnetic surface mode of the sphere. The absorption lines are shifted to higher energy and the transition oscillator strengths are changed by the resonance. The line shift is the same as the line shift that originates from the long-range electron-hole exchange interaction and was calculated by Goupalov and Ivchenko [1]. Taking into account both the short-range exchange interaction and the resonance shift, we find an excellent agreement with experimental data for CdSe nanocrystals. The line splitting in CdTe nanocrystals is calculated.