Reflectance anisotropy spectroscopy of metal nanoclusters formed on semiconductor surface

Optical anisotropy of indium nanoclusters formed on the (001) surface of indium arsenide was found by differential reflectance anisotropy spectroscopy. The fact of such an observation for nanocluster arrays unambiguously evidences the presence of their macroscopic anisotropy which could not be disclosed by conventional diagnostics techniques. The scale of the observed plasmonic anisotropy signal exceeds by two orders of magnitude the scale of anisotropy signals from valence-bond structures formed on a semiconductor surface. A resonant feature observed in reflectance anisotropy spectra is interpreted in the model of coupled dipole plasmons belonging to ellipsoidal nanoparticles. Estimation based on the experimental spectra shows that within the sample surface the lengths of ellipsoid semiaxes differ from each other by a few percent.