Optical phonons in Zn1-xCdxSe alloys

We report results of Infrared and Raman spectra studies of bulk Zn1–xCdxSe. The obtained concentration dependences of oscillator parameters, reveals an unusual behavior. Besides two transverse optical (TO) and longitudinal optical (LO) branches, which are typical for a one-mode behavior, an additional branch getting into TO-LO splitting region was observed. We explained the nature of these “inserted modes” on the basis of the microscopic theory, which well describes the quasi-local mode frequency and the sign of splitting. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)