Luminescence from quantized exciton-polariton states in Cd1−xZnxTe/CdTe/Cd1−xZnxTe thin-layer heterostructures

Abstract

Photoluminescence spectra, very different from those given by bulk CdTe, are obtained at 1.8 K, for two ${\mathrm{Cd}}_{0.92}$ ${\mathrm{Zn}}_{0.08}$Te/CdTe/${\mathrm{Cd}}_{0.92}$ ${\mathrm{Zn}}_{0.08}$Te quantum-well heterostructures. The thicknesses of the CdTe layers are 500 and 1000 Å, respectively, intermediate between a quasi-two-dimensional quantum well and the bulk. Zero-phonon free-exciton luminescence predominates over bound-exciton recombination; phonon replicas of the free exciton luminescence are not visible. Satellite peaks are observed over a 10-meV range on the high-energy side of the free exciton peak. These are attributed to quantized states of the exciton-polariton confined inside the CdTe layer. A simple theory is given for the relative emission probabilities associated with the quantized states; their energy positions are fitted with a series of indexed, discrete points on a polariton dispersion curve.