Effect of hydrogen dilution on photoluminescent properties of nanocrystalline SiC films deposited by helicon wave plasma CVD
2007
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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