We have used low temperature photoluminescence measurements in order to quantify the impact of strain effect on the Si indirect band gap in 9 nm thick tensely strained silicon on insulator layers. A redshift of the transverse optical phonon excitonic recombination in the strained silicon layer was evidenced as the strain in the layer is increased. Band gap shrinkages in the Δ direction equal to 130±3 meV, 184±3 meV, and 239±3 meV were obtained for 0.87±0.03%, 1.22±0.05%, and 1.54±0.06% strain values. These measured indirect transitions are in good agreement with the calculated strained silicon indirect band gap values.

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Low temperature photoluminescence has been performed in order to analyze the strain effect on the Si band structure for an 8 nm thick tensile strained silicon layer on insulator. The authors show three phonon assisted optical transitions related to the strained silicon top layer at 0.923, 0.983, and 1.022eV. The 0.983eV line of the TO phonon assisted transition corresponds to a 115meV strain induced band gap shrinkage at Δ point which agrees with the calculated values of strained silicon band gap.