Length dependence of the longitudinal optical phonon properties in CdZnSe/ZnSe quantum wires

This paper presents the results of Raman spectroscopic investigations on etched CdxZn1−xSe/ZnSe quantum wires with different wire lengths and wire widths. The recorded spectra show intensive signals in the region of the longitudinal optical phonons (LO) of the ZnSe barrier and the CdZnSe wire as well as several overtones. A strong outgoing resonance can be observed when the overtone position matches the luminescence peak position. The asymmetric LO signal can be separated into three distinct peaks: two higher wavenumber peaks, which are observed especially for the long and thick wires for short excitation wavelengths, are attributed to the LO phonon modes of the ZnSe barrier material and the strained CdZnSe wire; a shoulder at the low wavenumber region, which appears in the spectra of the short and thin wires, is attributed to an LO phonon excited in the strain relaxed wire edges.