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

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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 120W, 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 30min 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 520cm−1 related to the amorphous Si accompanied with the significant enhancement for SiC bond related peak at 980cm−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±0.5nm and the volume density of (3±1)×1018 (#/cm3) in Si-rich SiC film with R=70% are observed after annealing at higher temperature.