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 the intrinsic and dopant-related luminescent phenomena of wide bad-gap dielectrics. In this study, the luminescent properties of Mn- and Cr- doped single crystalline films of α-Al2O3 (sapphire), grown using the liquid phase epitaxy method from PbO-B2O3 flux onto C plane-oriented sapphire crystal substrates, 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 have shown 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 application potential of Al2O3:Mn and Al2O3:Mn single crystalline films in optoelectronic devices and luminescent sensors.