Uniaxial strain was introduced to Si-on-insulator (SOI) substrate by SiN deposition using electron cyclotron resonance sputtering followed by gate-opening using lift-off technique. Then thermal treatments were performed at different temperatures. Strain-relaxation was observed by Raman spectroscopy. Photoluminescence (PL) was used to evaluate defects generated during strain-relaxation. Defect-related PL signal was observed for the thermally-treated strained channel. The intensity of defect-related PL signal increased with increasing annealing temperature. The energy position and profile of defect-related PL signal also varied with annealing temperature and SiN thickness.