Phase-separated Si nanoclusters from Si oxide matrix grown by laser-assisted chemical vapor deposition

A CO2 laser was used in combination with a conventional plasma-enhanced chemical vapor deposition system to assist the decomposition of SiH4 molecules and to grow Si nanoclusters embedded in Si oxide films. The compositional and structural properties of the grown films were characterized by energy dispersive spectrometry (EDS) and Fourier transformation infrared (FTIR) spectrometry. A two phase mixture model of Si nanoclusters separated from the grown Si oxide matrix was proposed to explain the formation mechanism of Si nanoclusters embedded in the Si oxide matrix. The dependences of the photoluminescence photon energy and intensity on the CO2 laser power were observed. According to the model, the refractive indices of the Si oxide phase in the grown film were deduced and are in agreement with the theoretically calculated values. These results demonstrated the existence of laser-induced phase-separated Si nanoclusters. In addition, the relation between the sizes of Si nanoclusters and the CO2 laser power was also elucidated.