Singularity of polariton radiation of ZnTe crystals at high excitation levels
Brodin M.S., Goer D.B., Matsko M.G.
We investigated the emission spectra of ZnTe crystals (T=4.2 and 1.6 °K) excited by an argon laser. The results are interpreted in terms of polariton luminescence of the lower and upper polariton branches. The appearance of a narrow peak—"needle" (half-width » I0"s eV) for the emission of the upper polariton branch, at T = 1.6°K and at an excitation density 4xl021 photons/cm2 sec, is attributed to the possibility of attaining Bose-Einstein condensation of the excitons on the upper polariton branch in a state with fc =;0.