Photoexcited carriers and surface recombination velocity in InN epilayers: A Raman scattering study

Abstract

The effect of photoexcited electron-hole pairs on the LO-phonon-plasmon coupled modes has been observed in InN layers by means of micro-Raman experiments performed at different excitation laser powers. The L− Raman peak displays an upward shift of about 10 cm−1 over the range of increasing excitation powers studied. The L− behavior is well accounted for by a dielectric line-shape model based on the Lindhard-Mermin dielectric function. The photoexcited carrier density has been extracted from line-shape fits to the Raman spectra and a linear increase in the photoexcited carrier density with incident power is found. A simple diffusion model is used to estimate the surface recombination velocity in the layers, which is found to be in the 4.6–4.9 104 cm s−1 range for the bare InN surface.