Enhancement of photoluminescence at 1.54 μm from Er in strained Si and SiGe

We studied on the photoluminescence (PL) properties of Er in tensile-strained Si on a SiGe layer (Si:Er:O/SiGe) and compressively strained SiGe on a Si layer (SiGe:Er:O/Si) grown by molecular beam epitaxy (MBE). Er-related luminescence was observed around 1.54 μm in both tensile- and compressively strained samples. The PL intensities of strained Si:Er:O/SiGe and SiGe:Er:O/Si samples were much stronger than those of unstrained Si:Er:O/Si samples. Moreover, intensive luminescence was observed in strained samples with low Er concentrations far below 10¹⁸ cm^-3. The PL spectra of Si:Er:O/SiGe samples were broader than those of unstrained Si:Er:O/Si samples. On the other hand, no significant differences in the width between SiGe:Er:O/Si and unstrained samples were observed. These differences in the PL intensity between strained and unstrained samples strongly suggest that the optical activation of Er in Si and SiGe can be enhanced by the presence of strain.