Fluorescence spectroscopy of Cr3+ ions in MgO nanofilms on Al2O3 and GaN substrates

The 2E - 4A2 fluorescence spectra of probe Cr3+ centers in MgO nanolayers of different thickness deposited on Al2O3 and GaN substrates were studied. The films were produced by laser molecular beam epitaxy (LMBE). The spectra revealed the strong inhomogeneous broadening that prevents observation of spectral shifts and splittings due to lattice distortions. The measurements of the fluorescence lifetimes provided an indication of lattice distortions and may be used for diagnostics of the epitaxial oxide films.