The optical and electrical variation green and blue silicon quantum dot (Si-QD) based MOSLED with the
different thickness of SiO<sub>x</sub> layer has been demonstrated. The turn-on voltage of the Si-QDs based MOSLED
with the different RF plasma power is linearly enlarged by increasing the thickness of the SiO<sub>x</sub> layer. The turn-on
electric field is still constant at 6.6x10<sup>6</sup> V/cm. The EL emission power of the blue Si-QD based MOSLED
with increasing the thickness form 150 nm to 350 nm enhances from 55 nW to 470 nW due to the larger Si-QD
amount from 1.5x10<sup>18</sup> cm<sup>-3</sup> to 4.3x10<sup>18</sup> cm<sup>-3</sup> in higher thickness. The blue Si-QDs based MOSLED with the
SiO<sub>x</sub> thickness of 350 nm has the maximum EL power of 470 nW. The EL wavelength of the blue Si-QD based
MOSLED red-shifts from 420 nm to 450 nm when the SiO<sub>x</sub> thickness increasing from 150 nm to 350 nm. The
red-shifted phenomenon on EL spectra with increasing the thickness could be explained by means of the
relationship between the varied Si-QD size and degraded electron conductivity. The EL wavelength of the Si-QD based MOSLED has a band filling effect phenomenon by the increment of the biased current and thickness.
The distribution of Si-QD was uniform in whole SiO<sub>x</sub> layer although there existed different Si-QD size.