InN/In nanocomposites: Plasmonic effects and a hidden optical gap

InN/In nanocomposites with periodical In inclusions amounting up to 30% of the total volume exhibit bright emission near 0.7 eV explicitly associated with In clusters. Its energy and intensity depend on the In amount. The principal absorption edge in the semiconductor host, as given by a photovoltaic response, is markedly higher than the onset of thermally detected absorption. These findings, being strongly suggestive of plasmon-dominated emission and absorption, are discussed in terms of electromagnetic enhancement taking into account the In parallel-band transitions.