Effect of RF power on the formation and size evolution of nC-Si quantum dots in an amorphous SiOxmatrix

Abstract

The evolution of silicon quantum dots (Si-QDs) embedded in a-SiO_x matrix has been controlled by varying the RF power in the He-diluted SiH₄ plasma at a low substrate temperature of 300 °C in PECVD. By optimizing the plasma parameters, Si-QDs of very small size, down to ∼2 nm in diameter, with extremely narrow size dispersion at FWHM ∼1 nm and a very high density of ∼2 × 10¹² cm⁻² has been obtained. The effect of applied RF power controlling the growth mechanism of Si-QDs has been explained by using probable plasma chemistry of SiH₄ in He, inside the plasma. Si-QDs with such low dimension and with high density, embedded in a-SiO_x matrix, are being reported for the first time. SiO_x is the most preferred dielectric medium in device fabrication. This finding by direct plasma synthesis at low substrate temperature may provide strong impetus to the further development of optoelectronic and photonic devices based on Si-QDs.