Passivation of Liquid‐Phase Crystallized Silicon With PECVD‐SiN x and PECVD‐SiN x /SiO x

Silicon nitride (SiN x ) and silicon oxide (SiO x ) grown with plasma‐enhanced chemical vapor deposition are used to passivate the front‐side of liquid‐phase crystallized silicon (LPC‐Si). The dielectric layer/LPC‐Si interface is smooth and layers are well‐defined as demonstrated with transmission electron microscopy. Using electron energy loss spectroscopy a thin silicon oxynitride is detected which is related to oxidation of the SiN x prior to the silicon deposition. The interface defect state density ( D it ) and the effective fixed charge density ( Q IL,eff ) are obtained from high‐frequency capacitance‐voltage measurements on developed metal‐insulator‐semiconductor structures based on SiO x /SiN x /LPC‐Si and SiO x /SiN x /SiO x /LPC‐Si sequences. Charge transfer across the SiN x /LPC‐Si interface is observed which does not occur with the thin SiO x between SiN x and LPC‐Si. The SiO x /SiN x /LPC‐Si interface is characterized by Q IL,eff  > 10 12  cm −2 and D it,MG >10 12  eV −1  cm −2 . With SiO x /SiN x /SiO x stack, both parameters are around one order of magnitude lower. Based on obtained Q IL,eff and D it ( E ) and capture cross sections for electrons and holes of σ n  = 10 −14  cm s −1 and σ p  = 10 −16  cm s −1 , respectively, a front‐side surface recombination velocity in the range of 10 cm s −1 at both interfaces is determined using the extended Shockley‐Read‐Hall recombination model. Results indicate that field‐effect passivation is strong, especially with SiO x /SiN x stack.