Excitation density dependent photoluminescence spectra in GaMnN diluted magnetic semiconductor

The excitation density dependent photoluminescence (PL) spectra in Ga1-xMnxN layers (where x∼0.1-0.8%) grown on sapphire (0 0 0 1) substrates using the plasma-enhanced molecular beam epitaxy technique have been investigated. The efficient PL peaks are observed in the red (1.86 eV), yellow (2.34 eV), and blue (3.29 eV) spectral ranges. By examining the dependence of PL on the excitation laser power density at 15 and 300 K, the yellow band (2.34 eV) and bandgap (3.50 eV) luminescence vary linearly with the light intensity, which are in good agreement with a simple recombination model, which assumes a density of recombination centers below the conduction band edge.