Strong photoinduced reflectivity change in the midinfrared region in GaN is observed by femtosecond pump-probe measurements. By comparing the results of simultaneous emission and reflectivity measurements, we show that midinfrared reflectivity spectra are governed by coupled phonon-plasmon modes and spatial inhomogeneity of carrier density. Even when the plasma frequency lies in the far infrared region at low carrier density of 1018cm−3, the strong plasmon-phonon coupling drives the position of upper phonon-plasmon mode to midinfrared region, allowing us to investigate dynamics of photogenerated free carriers in GaN-based materials by midinfrared reflectivity measurements.
ASJC Scopus subject areas
- Physics and Astronomy (miscellaneous)