The study reported in this paper contributes to better understanding the thermal oxidation effect on structural and optical properties of polycrystalline silicon heavily in situ P-LPCVD films. The deposits, doped at levels 3×1019 and 1.6×1020 cm−3, have been elaborated from silane decomposition (400 mTorrs, 605°C) on monosilicon substrate oriented 〈111〉. The thermal oxidation was performed at temperatures: 850°C during 1 hour, 1000, 1050, and 1100°C during 15 minutes. The XRD spectra analysis pointed out significant 〈111〉 texture evolution, while in the case of 〈220〉 and 〈311〉 textures, the intensities are practically invariant (variations fall in the uncertainty intervals). The optical characterizations showed that refractive index and absorption coefficient are very sensitive to the oxidation treatment, mainly when the doping level is not very high. We think that atomic oxygen acts as defects passivating agent leading to carriers’ concentration increasing. Besides, the optical behavior is modeled in visible and near infrared, by a seven-term polynomial function n 2=f(λ 2), with alternate signs, instead of theoretically unlimited terms number from Drude’s model. It has been shown that fitting parameters fall on Gaussian curves like they do in the theoretical model.
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