Anomalous excitation-power dependence of band-edge emission in Si involving radiation-induced defects

Abstract

We report on the anomalous excitation-power dependence of the band-edge emission in Si after 2 MeV electron irradiation. It is well-established that the dependence of the emission intensity I on the excitation power L is generally follows the power law, I ∝ Ln with the exponent n between 1 and 2. However, the exponent n increases after the electron irradiation and becomes larger than 2 at temperatures from 60 to 150 K in all the measured samples. The present dependence can be explained by a simple model: the radiation-induced defects act as dominant recombination centers in the low excitation-power range, but their activity becomes saturated in the high excitation-power range.

Calibration curve for the photoluminescence method after electron irradiation for quantifying low-level carbon in silicon

“…We assume that the radiative recombination of the G-line is monomolecular process, since the excitation power dependence of the G-line is nearly linear. 20,21) Then, the G-line intensity (G) is proportional to N G , and is expressed by…”

“…A strong saturation effect in the excitation power dependence of the C-line also makes the analysis complicated, which will be described in a separate paper. 21) 3. Experimental method 3.1.…”

“…25,33,34) However, the radiation-induced defects involving dopant impurities, such as interstitial B and O complexes (B i O i ), 31,35,36) may affect the near-edge emission and G-line intensities. 37) This is just one example for p-type conductive samples and more work needs to be done to discuss the applicability to p-type conductive samples. Nonetheless, the present results demonstrates the applicability of the revised calibration curve to wide range of MCZ samples with resistivity of higher than 50 Ω • cm.…”

Detection limit of carbon concentration measurement in Si for photoluminescence method after electron irradiation

“…The detection limit concentration at 30 K for 1 h accumulation was calculated to be about 3 × 10 13 cm −3 in the same way as the case at 4.2 K because the calibration curve at 4.2 K was reported to be valid also at 15 and 77 K. 20) The increment of the excitation power is a straightforward way to improve the detection limit. Since the excitationpower dependence of the G-line is nearly linear, 32) the detection limit can be reduced to approximately 2 × 10 13 cm −3 when the excitation power is increased from 50 mW to 200 mW at 30 K with 1 h accumulation time. Figures 6(a)-6(c) show PL spectra at 4.2 K under the excitation power 50, 100, and 200 mW, respectively, and Fig.…”

Free-to-bound emission from interstitial carbon and oxygen defects (CiOi) in electron-irradiated Si

“…A strong saturation effect in the excitation power dependence of the C08-band also makes the quantitative analysis complicated, which will be described in a separate paper. 34,35) In conclusion, we determined the entire spectral shape of the C08-band observed commonly in Si by room-temperature photoluminescence after electron irradiation. The band has a peak at 0.77 ± 0.01 eV with long tails on both sides.…”