We studied on the effect of the strain on photoluminescence (PL) properties of Er-doped Si on a SiGe layer (Si:Er:O/SiGe) and Er-doped SiGe on a Si layer (SiGe:Er:O/Si) grown by molecular beam epitaxy. Er-related luminescence was observed around 1.54 mum in all the samples. The PL spectra of the Si:Er:O/SiGe samples are much broader and stronger than those of the Si:Er:O/Si samples prepared as reference. Moreover, the intensive luminescence was observed in the Si:Er:O/SiGe sample that had much lower Er concentration of about 2.5 x 10(16) cm(-3). On the other hand, the significant differences in the PL spectra between the SiGe:Er:O/Si and Si:Er:O/Si samples were not observed. These indicate that the tensile strained Si enhances the optical activation of Er. (C) 2003 Elsevier B.V. All rights reserved.