Relaxation processes at high excitation levels and Bose-Einstein condensation of excitons in ZnTe crystals

The singularities of low-temperature emission spectra obtained for ZnTe crystals excited resonantly by a strongly monochromatic source are investigated. The possibility of attaining the coherent luminescent emission due to the exciton-exciton interaction under these conditions is proved. The appearance of the non-polarized needle-like peak and the processes of inelastic interaction of polaritons of the upper polariton branch (UPB) as well as the disappearance of the Raman component are interpreted as the spectral attributes of Bose-Einstein condensation of UPB polaritons.