The emission from ZnO layers grown on the surface of bulk opals using chemical deposition is studied under excitation by the 351.1 nm line of an Ar+ laser at different excitation power densities and temperatures. The emission spectrum exhibits narrow photoluminescence (PL) bands associated with the recombination of bound and free excitons as well a relatively broad band around 3.31 eV. The width of the excitonic lines (2-3 meV) along with their energy position are indicative of the high quality and strain-free state of the layer. The origin of the 3.31 eV PL band is discussed in connection with its dependence upon the excitation power density and temperature.

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