Reflectivity and photoreflectivity spectra of structures with quantum wells based on ZnO

Reflectivity and modulated photoreflectivity spectra of ZnO and Zn$_{1-x}$Mg$_{x}$O epitaxial layers as well as ZnO/Zn$_{1-x}$Mg$_{x}$O quantum wells have been studied at normal and oblique light incidence. Comparison of experimental and calculated spectra allowed refinement of certain parameters of excitons in these structures and the order of energy bands in ZnO.