Plasmonic effects in In(Ga)N

摘要

This paper reports on two plasmonic systems based on Ⅲ-Nitrides: (i) InGaN - Au nanoparticles; (ii) InN with spontaneously formed buried In nanoparticles. By using NSOM and u-PL studies we established necessary conditions for the efficient interaction of localized plasmons excited in a gold nanoparticle with localized excitons situated near the InGaN surface. The tens-fold PL intensity enhancement was observed for ~100 nm Au nanoparticles. The narrow lines of single excitons have been registered at low temperature. Due to specific thermodynamic properties of InN, its optical properties are strongly influenced by plasmons in spontaneously formed In nanoparticles. The μ-CL study of MBE grown InN/In structures with intentional periodic 0-48 ML In insertions has shown that the bright CL spots (peaked spectrally at ~0.7eV) coincide always with the agglomerates of In nanoparticles. The intensity increase by the factor of ~10~2 is in good agreement with calculations of the average enhancement factor in InN/In nanocomposites comprising the nanoparticles of an arbitrary shape and orientation. Time-resolved PL studies have demonstrated pronounced Purcell effect, i.e. significant shortening of spontaneous recombination rate, in both systems. Terahertz emission (~3 THz) observed in InN epilayers under electrical pumping is ascribed to surface plasmon polariton waves coupled to electromagnetic field at quasi-periodical structural imperfections.