XANES Analysis of Optical Activation Process of Er in Si:Er2O3 Thin Film: Electronic and Structural Modifications around Er

Peak height and second-derivative analyses of Er L III -edge X-ray absorption near edge structure (XANES) are performed to investigate the optical activation process of Er in Si:Er 2 O 3 thin film produced by the laser ablation method. The as-ablated sample has a high resonant absorption peak, and the second-derivative analysis of the peak gives a singlet in contrast to the doublet for Er 2 O 3 powder. This is explained by the concentration of the density of states (DOS) due to a higher order symmetry such as an ErO 6 octahedron in the as-ablated sample. After annealing, a quasi-doublet is observed in the second-derivative spectrum, suggesting the distortion of the octahedral structure. The increment of photoluminescence intensity after annealing is considered to be caused by this symmetrical degradation.