NEW SPECTROSCOPIC DATA OF ERBIUM IONS IN GaN THIN FILMS

摘要

Optical properties of erbium ions in MBE- grown GaN-thin films are reported. Three types of sites are identified using laser site selective excitation. The main center is ascribed to Er~(3+) ions substituted on the Ga sub-lattice while the two other centers are assigned to Er-related defects. The lifetimes of the ~4S_(3/2) and ~4I_(13/2) multiplets of the main center are strongly quenched with increasing Er concentration. The complex decay profile of the visible fluorescence and its concentration dependence were modeled and interpreted using the diffusion-limited model. All the microscopic parameters of the interaction were determined. The dynamic of the infrared emission at 1.54μm from the ~4I_(13/2) multiplet after excitation in the visible range is discussed. The energy of the Stark components of the ground state were determined and from the overall splitting, the crystal field strength was deduced. Comparison of the result with those obtained in inorganic materials indicates that the rare earth is well embedded in the semiconductor host and not in a parasitic oxide phase.