Infrared luminescence of erbium-silicon-oxide crystalline compound on silicon

The photoluminescence (PL) properties of crystalline Er-Si-O compound on silicon substrate prepared using a simple method through evaporation and thermal annealing have been investigated. Diffraction peaks corresponding to crystalline Er-Si-O were clearly detected in X-ray diffraction measurements. Er-related infrared luminescence was observed at around 1.52 μm at room temperature. This luminescence of the crystalline Er-Si-O compound on Si was due not to direct excitation of the 4f shell of Er³⁺, but to excitation of the host Si, i.e. indirect excitation. The observed luminescence was very intense compared with that of a sample prepared by a wet-chemical method using ErCl₃. The Er-related PL spectra also showed several peaks at room temperature, which reflected the splitting patterns of ground manifolds (⁴I_15/2) for the 4f¹¹ shell of Er³⁺. Significant differences in peak wavelengths between the crystalline Er-Si-O compound on Si substrate and Er-doped Si on Si substrate (Si:Er:O/Si) grown by molecular beam epitaxy were observed in the PL spectra at 77 K. In addition, temperature quenching of Er-related infrared luminescence was greatly reduced in the crystalline Er-Si-O compound prepared using the simple method. Finally, a new electron spin resonance spectrum was detected for the crystalline Er-Si-O compound on silicon substrate, thought to be related to the presence of Er atoms in the compound.