Luminescent properties of Mn and Cr doped Al2O3 single crystalline films under excitation with synchrotron radiation

Excitation with synchrotron radiation has provided a powerful means to study wide bad-gap dielectrics' intrinsic and dopant-related luminescent phenomena. In this study, the luminescent properties of Mn- and Cr- doped single crystalline films of Al2O3 (sapphire), grown using the liquid phase epitaxy method from PbO-B2O3 flux, were systematically investigated using absorption and cathodoluminescence spectra as well as the conventional and advanced photoluminescent spectroscopy under synchrotron radiation excitation. The emission and excitation spectra showed characteristic bands corresponding to Mn4+ and Cr3+ impurities as well as Pb2+ flux-related dopants and indicated the participation of these metal ions in the luminescence process. The influence of the excitation energy in the transparency region and exciton range of the Al2O3 host on the intensity and spectral shape of the emissions bands of these dopants is discussed in detail. The obtained results contribute to understanding the potential of Al2O3:Mn and Al2O3:Cr films for applications in optoelectronic devices and luminescent sensors.