Abstract
Nanocrystalline silicon carbide (nc-SiC) thin films were deposited by helicon wave plasma enhanced chemical vapor deposition (HW-PECVD) technique at different hydrogen dilution ratio (RH). The PL peak energy and intensity were systemically analyzed using photoluminescent (PL) and photoluminescent excitation (PLE) methods. As a whole, the PL intensity shows an increasing trend and the PL peak energy presents continuous blue shifts with increasing hydrogen dilution ratio. In addition, it is found that the spectra band of samples deposited at low RH are composed of two components, the high energy band comes from quantum confinement effect and the low energy band is related to radiation of surface defect. The low energy band has a decreasing trend with increasing hydrogen dilution ratio and even disappears finally at high RH. We explain dependence of PL properties in terms of the variation of film microstructure induced by hydrogen dilution during film deposition. The increasing of PL intensity and the decreasing of the low energy band can both be accounted by the microstructure improvement. The decrease of PL peak energy is related to the size decrease of SiC nanocrystals.
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