Nanocomposites, comprising metallic nano-clusters inside a semiconductor matrix, are promising materials for rapidly developed plasmonics which suggests new concept of light manipulation and generation [1]. Optical properties of the nanocomposites are controlled by collective electron excitations in metallic inclusions or localized plasmons (Mie resonances) [2]. These materials can exhibit a huge discrepancy between the characteristic energies of optical processes, which match well in a semiconductor, because they occur in spatially different areas which undergo the different influence of the plasmons [3]. The basic properties of the nanocomposites are studied using InN/In with metallic clusters formed both spontaneously and by periodic deposition of In insertions. It is found that the spots of intense cathodoluminescence (CL) is strongly correlated with the agglomerations of the In clusters due to plasmon-induced enhancement. With increasing In amount, the peaks of thermally detected optical absorption (TDOA) and CL move in the opposite directions because of different plasmonic effects in the well-separated clusters and their dense agglomerations. Furthermore, a strong difference is discovered between the onsets of TDOA and photocurrent. This feature is a key to distinguish InN/In from InN; without that, optimization of a structure using absorption or emission data does not guarantee its applicability, e.g., for full-spectrum solar cells. To simulate the plasmonic effects in the nanocomposites, a model has been proposed, which considers the clusters as spheroids of random shapes and orientations. The calculated spectra of the averaged enhancement are in reasonable agreement with optical data. The conditions of terahertz generation in the plasmonic nanocomposites are analyzed and compared with experimental findings as well.

[1] E. Ozbay, Science 311, 189 (2006).

[2] T.V. Shubina et al., Phys. Rev. Letters 92, 117407 (2004).

[3] T.V. Shubina et al., Phys. Rev. B 79, 153105 (2009).

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1. Plasmonic effects in InN-based structures with nano-clusters of metallic indium