Optical properties of GaN-based magnetic semiconductors

Optical properties of GaCrN, GaDyN and GaGdN have been studied by means of photoluminescence spectroscopy having spectral and time resolution. Photoluminescence (PL) emission at around 3.29 eV was determined to be the band-to-band transition of GaCrN. The PL decay time of GaCrN depends on emission energy. For GaDyN, Dy3+, ions in host GaN exhibited several sharp peaks originating from the intra-4f orbital transitions of the series of F-4(9/2)-H-6(J) (J=15/2, 13/2, ...), and the lifetime of the F-4(9/2)-H-6(13/2) transition was as long as 87 Its at 13 K. The broad defect level for GaDyN provides an efficient pathway for the carrier-mediated energy transfer between Dy3+ ions and the GaN host. However, no such evidence is found between Gd ions and GaN in the GaGdN layer.