Exciton-polariton resonances in light absorption spectra of semiconductor superlattices and crystals

摘要

Abstract: The absorption-edge spectra have been studied in the temperature range from 4 to 300 K for single-crystal CdTe, ZnTe, GaAs wafers and GaAs/(Al,Ga)As multiple quantum well structures. In all cases the frequency integrated absorption coefficient K is found to increase monotonously with temperature T up to T $EQ T$+*$/ and to keep constant above T$+*$/. The temperatures T$+*$/, depending on semiconducting materials, might be considered as critical ones corresponding to a change in polaritonic energy transport mechanism due to the lack of spatial dispersion at T$GRT@T$+*$/. It was shown, that though the measured temperatures T$+*$/ $APEQ 10$+2$/ K correspond to much larger linewidths than could be explained by using the theoretical value of the exciton damping parameter, this discrepancy can be overcome if a temperature- dependent inhomogeneous broadening is taken into account consistently.!26