Nanocrystalline silicon embedded in silicon suboxide synthesized in high-density inductively coupled plasma

A two-phase material system of nanocrystalline silicon (nc-Si) embedded in a dielectric matrix of silicon suboxide (SiO_x) is fundamentally and technologically significant for the photonic and photovoltaic device such as light emission diode and solar cells. nc-Si in amorphous SiO_x has been synthesized by means of the low-frequency (460 kHz) inductively coupled plasma (LFICP) of SiH₄ + CO₂ + H₂ without the common route of high hydrogen dilution. The chemical composition, microstructures and optical properties of the complex material system are tuned by the reactive gas flow rate ratio of CO₂/SiH₄. nc-Si embedded in amorphous SiO_x due to the phase separation are observed by means of SEM and TEM characterization tools. The crystalline volume fraction in nc-SiO_x:H is determined by the density of the embedded nc-Si particles and the occurrence of the a-SiO_x encapsulating shell layer. The bond configuration analysis shows the concurrent oxygenation and dehydrogenation process with the incorporation of oxygen. The underlying mechanism in forming the two-phase complex material system and the phase evolution with the reactive gas flow rate ratio are discussed in terms of the unique features of the utilized high-density LFICP.