Photoluminescence spectra of ZnO layers obtained by radical-beam epitaxy have been studied. Photoluminescence of free $B$ and $C$ excitons has been observed. At a high excitation level a band with ${\lambda }_{\max }=363.1\mathrm{}\hspace{0.5em}\mathrm{nm}$ is observed. It is explained in terms of the proposed photoluminescence polariton mechanism in the $B_{n=1\mathrm{}}$ exciton spectral region through biexcitons

• Received 28 January 1998

DOI:https://doi.org/10.1103/PhysRevB.58.10692