Surface and volume plasmons in metallic nanospheres in a semiclassical RPA-type approach: Near-field coupling of surface plasmons with the semiconductor substrate

摘要

A random-phase-approximation semiclassical scheme for the description of plasmon excitations in large metallic nanospheres, with a radius range of 10-60 nm, is developed in an all-analytical version, with inclusion of irradiation phenomena. The spectrum of plasmons is determined for both surface- and volume-type excitations. The various channels for the damping of surface plasmons are evaluated and a predominant role of the irradiation losses is indicated for large metallic nanospheres, with radius greater than 10 nm. The damping-caused plasmon resonance shifts are compared with the experimental data for metallic nanoparticles of different sizes located in a dielectric medium or on the semiconductor substrate. The strong enhancement of energy transfer from the surface plasmon oscillations to the semiconductor substrate is explained in the regime of a near-field coupling of surface plasmons with semiconductor electrons in agreement with recent experimental observations for metallically surface-nanomodified photodiode systems.