Photoluminescence (PL) intensity and wavelength control of Si-rich SiOx film and Si-rich SiOx based MOSLED achieved by detuning plasma power (RF power) during plasma-enhanced chemical vapor deposition (PECVD) growth is investigated. The peak of PL spectrum blue-shifts from 780 to 400 nm by modifying the RF power form 20 to 70 W during PECVD growth. The average sizes of Si nanocluster under RF power of 60 and 70W are 2.61 and 1.83 nm, respectively. The EL color of Si nanocrystal (nc-Si) based MOSLEDs can be tunable among orange-red, green and blue colors by growing the SiOx films with PECVD under different RF power. Under RF power from 50 to 70W, the turn-on voltage of nc-Si based MOSLEDs increases from 26 to 60 V, the optical power also increases from 1.6 W/cm2 to 9.7 W/cm2 and the power-current slope are 0.51, 3.24 and 62.92 mW/A, respectively.