Plasma Synthesis of 2D Layered SiC NCs with High PL QY

Silicon carbide nanocrystals (SiC NCs) with bright photoluminescence (PL) are of current interest for a range of potential applications, such as bioimaging, bio-photonics, and diagnostics and fabrication of optical nanodevices. Here, we use the liquid precursor tetramethylsilane (Si(CH₃)₄) for the plasma synthesis of two dimensional (2D) SiC NCs with exemplary surface emission. Through processing executed in an oxygen-shielded environment, we achieve PL quantum yields (QYs) approaching 70%. TEM/AFM on the colloid show NCs with lateral size ~ 5-10 nm and sub-nm thickness, with crystallinity and thickness confirmed by XRD and TEM. Raman spectra show no optical phonon splitting relative to the bulk, characteristic of 2D materials, and consistent with the layered structure of the flakes. FTIR shows that predominance of Si-OCH₃ at the surface plays a major role in the enhancement of the photophysical properties in the over confined 2D SiC NCs. The results offer additional insight into the photophysical interplay of the nanocrystal surface, and quantum confinement.