Photoluminescence spectroscopy and energy-level analysis of metal-organic-deposited Ga2O3:Cr3+ films

The aims of this study are (i) to demonstrate the synthesis of Cr3+-activated beta-Ga2O3 films by metal-organic deposition and (ii) to report the temperature-dependent photoluminescence (PL) properties of such films from 20 to 300 K. An activation energy of similar to 0.9 eV for the Cr3+ ions in beta-Ga2O3 is determined from a plot of PL intensity vs calcination temperature. The red-line emission doublet R-1 and R-2 at similar to 1.8 eV and the broad emission band with a peak at similar to 1.7 eV are ascribed to the Cr3+ ions in the beta-Ga2O3 host. The energies of the excited states, i. e., E-2, T-4(2), T-2(2), T-4(1), and T-4(1), in Cr3+ are determined from the experimental PL and PL excitation spectra using a newly developed analysis model. The high-energy luminescence tail of the broad T-4(2) -> (4)A(2) emission band can be explained by the hot-carrier effect of the photoexcited electrons in the T-4(2) state. The relative intensities of the R-line emission doublet can also be explained very well by the population and depopulation of the electron numbers in the (E) over bar (R-1) and 2 (A) over bar (R-2) states. PL properties, such as the temperature-dependent PL intensity, peak energy, and spectral width, are analyzed in detail. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4754517]