As Si is an indirect band gap material, the PL generated by phonon assisted band-to-band (B2B) radiative recombination (of energy equal to energy gap of Si) is very weak; about 10 orders of magnitude lower than the exciting photon flux [1]. If crystallographic defects are present then at room temperature an additional broad defect PL peak is generated (DPL) with energy smaller than the band gap of Si [1], [2], [3] . At room temperature, defect-band PL intensity is orders of magnitude lower than the B2B intensity [1].
