The time evolution of the optical emissions of Ar plasma during silicon nanocrystal (SiNC) fabrication using a pulsed SiH4 supply is studied. The enhancement of Ar emission with a duration longer than the ON time of the pulsed SiH4 supply is observed owing to the formation of SiNCs in the plasma. This enhancement can be explained in terms of the increase in the number of high-energy electrons caused by electron attachments to SiNCs. The size and generation rate of SiNCs clearly correlate with the duration and intensity of the enhanced emission even when the Ar flow rate or the plasma power is changed. On the basis of this relationship, the size and density of SiNCs can be predicted during the fabrication by monitoring the enhanced emission.

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