INFLUENCE OF C⁺-IMPLANTATION DOSE ON BLUE EMISSION AND MICROSTRUCTURES OF Si-BASED POROUS \beta-SIC

Crystal Si were implanted with different doses of C⁺ from 10¹¹ to 10¹⁷ cm^-2 at an energy of 50 keV. \beta-SiC precipitates were formed by thermal annealing at 1050 ℃ for 1 h and porous structures were prepared by electrochemical anodization. Under the excitation of ultraviolet, the samples, with C⁺ dose ≥10¹⁵ cm^-2 have intense blue emission which is stronger than the photoluminescence (PL) intensity of reference porous silicon (PS), and increases as C⁺ dose increases; the samples with C⁺ dose ≤10¹⁴ cm^-2 show similar PL spectra to those of PS. The blue peak intensity in PL spectra is correlated with the TO phonon absorption strength of \beta-SiC in infrared absorption spectra. The transmission electron microscopy study shows that the blue peak is also correlated with the microstructures. Because porous \beta-SiC is nanometer in size, it is suggested that the quantum confinement effect be responsible for the blue light emission.