Mixed optical phonon modes in semiconductor nanocrystals synthesized in porous Al₂O₃ matrix

This work is devoted to experimental and theoretical studies of optical phonons confined in CdS nanocrystals grown inside a porous alumina matrix. The complete sets of phonon modes, confined in a spherical quantum dot and in a cylindrical quantum wire, are considered in the framework of a continuum model, which allows the mixing of all the expected types of vibrations. It is shown that the calculated phonon-related response in the far-infrared spectral region agrees qualitatively with the measured spectra of typical samples, providing an explanation for a rather unusual structure of the reflection and transmission spectra. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)