On the benefits of counting single photoluminescence photons for the investigation of low injection lifetime and traps in silicon

The time correlated single photon counting (TCSPC) technique offers a high sensitivity to low light intensities and a wide dynamic range from nanoseconds to seconds. In this paper we demonstrate the versatility of TCSPC for purposes of the highly sensitive electric characterisation of silicon, complementing the established analogous PL characterisation metrology. Using TCSPC we show that the charge carrier lifetime in silicon may be determined down to very low injection levels of 106 cm−3 with a purely dynamic approach. By observing the decay characteristics of the charge carrier density in Cz silicon in the nanosecond to second time regime we obtain the up to now most unambiguous support for the existence of two deep electron trap levels located in the band gap of silicon.