The Role of Radiative Surface Modes and Longitudinal Excitons in the Formation of Exciton-Polariton Luminescence Spectra of CdS-Type Crystals
Аннотация
The low-temperature (T = 2 K) exciton-polariton luminescence (EPL) spectra in the vicinity of the exciton-resonance frequency 1 n A = for CdS-type crystals have been theoretically and experimentally investigated with allowance for the mechanical exciton decay . The results of the numerical calculations of the partial and interference contributions of the bulk and radiative surface spectral modes to the EPL in the geometry of additional s-and p-polarized waves emitted into vacuum are analyzed. It is shown that the contributions of purely longitudinal excitons and their interference with polaritons of the upper dispersion branch near the longitudinal frequency L to the EPL are small (~10% -30%); nevertheless, they must be taken into account to obtain quantitative agreement with experimental data. Specifically these contributions are responsible for the formation of an additional L A line (along with the fundamental T A line) in the case of oblique incidence of radiation.