We demonstrate that a broad emission band is observable at room temperature in the vicinity of the carbon-related C-line detected at cryogenic temperatures in electron-irradiated Si. Its spectral shape is different from similar shapes of the bands due to dislocations, oxygen precipitates, and thermal donors. The band is annealed out at 450 °C and its intensity ratio to the band-edge emission has a positive correlation with carbon concentration in the same manner as the C-line. We deduce that the band has a very similar origin to the C-line and discuss the possibility of carbon quantification by using the ratio as an index.

We demonstrated the effectiveness of photoluminescence (PL) measurement at liquid N temperature after electron irradiation for the determination of the C concentration in P-doped n-type Czochralski-grown Si crystals. The disappearance of P-related lines simplifies the spectral analysis at 77 K, enabling us to estimate the C concentration from the G-line intensity ratio regardless of the difference in P concentration. The C concentration estimated by PL measurement at 77 K was in good agreement with those by measurement PL at 4.2 K and IR absorption. Unsusceptibility to the concentration of dopant impurities is a practical advantage of the PL measurement at 77 K over that at 4.2 K.

We have analyzed the effects of the surface recombination and the excitation power on the photoluminescence (PL) spectra in Si at room temperature in relation to the possible errors in the PL method after electron irradiation for the quantification of carbon in Si. The surface passivation enhances the band-to-band emission substantially but only slightly the carbon-related emission band. This variation produces an error in the carbon quantification, since the ratio between the two emissions is used as a measure of the carbon concentration. We show that the variation is caused by different excitation power dependence of the two emissions.

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