Self-aggregated Si quantum dots in amorphous Si-rich SiC

Amorphous silicon quantum dots (Si-QDs) self-aggregated in silicon-rich silicon carbide are synthesized by growing with plasma-enhanced chemical vapor deposition on (100)-oriented Si substrate. Under the environment of Argon (Ar)-diluted Silane (SiH4) and pure methane (CH4), the substrate temperature and RF power are set as 350 °C and 120 W, respectively, to provide the Si-rich SiC with changing fluence ratio (R = [CH4 ]/[SiH4] + [CH4]). By tuning the fluence ratio from 50% to 70%, the composition ratio x of Si-rich Si1 − xCx film is varied from 0.27 to 0.34 as characterized by X-ray photoelectron spectroscopy (XPS), which reveals the component of Si2p decreasing from 66.3 to 59.5%, and the component of C1s increasing from 23.9% to 31% to confirm the formation of Si-rich SiC matrix. Annealing of the SiC sample from 650 °C to 1050 °C at 200 °C increment for 30 min induces the very tiny shift on the wavenumber of the crystalline Si (c-Si) related peak due to the precipitation of Si-QDs within the SiC matrix, and the Raman scattering spectra indicate a broadened Raman peak ranging from 410 to 520 cm− 1 related to the amorphous Si accompanied with the significant enhancement for SiC bond related peak at 980 cm− 1. From the high resolution transmission electron microscopy images, the critical temperature for Si-QD precipitation is found to be 850 °C. The self-assembly of the crystallized Si-QDs with the size of 3 ± 0.5 nm and the volume density of (3 ± 1) × 1018 (#/cm3) in Si-rich SiC film with R = 70% are observed after annealing at higher temperature.

► The Si1 − xCx film with composition of C/Si could be tuned from 0.36 to 0.52. ► The Si-QDs are self-aggregated by increasing annealing temperature upper to 850 °C. ► The intensity of SiSi bonds are enhanced by increasing the annealing temperature.