Fröhlich vibrational modes in porous ZnSe studied by Raman scattering and Fourier transform infrared reflectance

Abstract

Arrays of parallel pores with a diameter of around 60 nm have been introduced by anodic etching in ZnSe single crystals with a free electron concentration of 4 × 1017 cm−3. Porosity-induced Fröhlich vibrational modes were studied by Raman scattering and Fourier transform infrared spectroscopy. The experimental data are compared with the results of theoretical simulation based on the effective medium theory. Traces of Se phase were evidenced at the surface of the porous matrix after anodization, the Raman active modes of this phase being incident in the region of the occurrence of Fröhlich vibrational modes inherent to porous ZnSe. To identify reliably the Fröhlich modes, Raman spectra of porous ZnSe layers were explored under different resonance conditions with several excitation wavelengths and various excitation power densities.