We have investigated the reflectivity of GaAs thin layers in the excitonic absorption region, observing detailed interference structures which reveal the polariton dispersion and the quantization of the exciton centre-of-mass motion. To analyse the experimental spectra, we have calculated the optical properties of thin films using a real-space density-matrix approach adapted to the case of degenerate valence bands. The oscillatory behaviour of the reflectance is well reproduced; a surface layer where the polarization decreases to zero is computed and its thickness is found to be energy dependent. The temperature dependence shows a broadening of the fine structure due to the phonon interaction and a decoupling of excitons and photons at high temperature.
EXCITONIC POLARITON INTERFERENCE IN THE REFLECTANCE OF GAAS THIN-FILMS
TREDICUCCI, ALESSANDRO;
1993
Abstract
We have investigated the reflectivity of GaAs thin layers in the excitonic absorption region, observing detailed interference structures which reveal the polariton dispersion and the quantization of the exciton centre-of-mass motion. To analyse the experimental spectra, we have calculated the optical properties of thin films using a real-space density-matrix approach adapted to the case of degenerate valence bands. The oscillatory behaviour of the reflectance is well reproduced; a surface layer where the polarization decreases to zero is computed and its thickness is found to be energy dependent. The temperature dependence shows a broadening of the fine structure due to the phonon interaction and a decoupling of excitons and photons at high temperature.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
