Photoluminescence from intermediate phase silicon structure and nanocrystalline silicon in plasma enhanced chemical vapor deposition grown Si/SiO2 multilayers

Amorphous Si/SiO2 multilayers (MLs) on silicon wafers were fabricated in a plasma enhanced chemical vapor deposition system via cycles of silicon deposition and plasma oxidation. The structural and optical properties of the MLs were characterized using transmission electron microscopy, Raman scattering and room temperature photoluminescence (PL) measurements. Intermediate phase silicon structure (IPSS), which is intermediate in order between the continuous random network amorphous phase and the well ordered crystalline phase, was found in the a-Si sublayers around the crystallization onset temperature. Red-near infrared wavelength region PL from recombination via structural defects inside the IPSS and Si = O at the surface of both nanocrystal Si (nc-Si) and IPSS was observed. In the samples with IPSS and nc-Si coexisting, the IPSS was found to be about five times more efficient as regards PL than nc-Si