Photoluminescence spectroscopy and energy-level analysis of metal-organic-deposited Ga 2O 3:Cr 3+ films

Abstract

The aims of this study are (i) to demonstrate the synthesis of Cr 3+-activated β-Ga 2O 3 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 ∼0.9 eV for the Cr 3+ ions in β-Ga 2O 3 is determined from a plot of PL intensity vs calcination temperature. The red-line emission doublet R 1 and R 2 at ∼1.8 eV and the broad emission band with a peak at ∼1.7 eV are ascribed to the Cr 3+ ions in the β-Ga 2O 3 host. The energies of the excited states, i.e., 2E, 4T 2, 2T 2, 4T 1, and 4T 1, in Cr 3 are determined from the experimental PL and PL excitation spectra using a newly developed analysis model. The high-energy luminescence tail of the broad 4T 2 → 4 → A 2 emission band can be explained by the hot-carrier effect of the photoexcited electrons in the 4T 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 Ē (R 1) and 2Ā (R 2) states. PL properties, such as the temperature-dependent PL intensity, peak energy, and spectral width, are analyzed in detail. © 2012 American Institute of Physics.