Role of ultra thin SiO_x layer on epitaxial YSZ/SiO_X/Si thin film as multi functional buffer layer by nano-probe and in-situ TEM investigation

摘要

The role of an ultra thin SiO_x layer for epitaxial growth of a YSZ (Y stabilized ZrO_2) thin film on a (001) Si substrate through the SiO_x layer was investigated by high resolution transmission electron microscope (HRTEM), in-situ heating transmission electron microscope and nano-beam diffraction (NBD) methods. It is found that a trace of epitaxial crystallinity remains in an ultra thin SiO_x layer within 2 nm from SiOx/Si interface. According to this result, a YSZ layer could epitaxially grow only on an ultra thin 1-2nm SiOx layer. It is also found that an ultra thin SiO_x layer has another effect to relax the crystallization strain at a YSX/Si interface. These results indicate that an ultra thin SiO_x layer plays two important roles (a) an ultra thin SiO_x layer formed just above the Si surface serves as a medium for the epitaxial growth of a YSZ layer, and (b)even in an ultra thin SiO_x is able to relax the crystallization strain of YSZ layer at YSZ/Si interface. These are the critical points of the epitaxial growth of YSZ/SiO_x/(001)Si thin film together with a role of an oxygen source reported previously.The role of an ultra thin SiO_x layer for epitaxial growth of a YSZ (Y stabilized ZrO_2) thin film on a (001) Si substrate through the SiO_x layer was investigated by high resolution transmission electron microscope (HRTEM), in-situ heating transmission electron microscope and nano-beam diffraction (NBD) methods. It is found that a trace of epitaxial crystallinity remains in an ultra thin SiO_x layer within 2 nm from SiOx/Si interface. According to this result, a YSZ layer could epitaxially grow only on an ultra thin 1-2nm SiOx layer. It is also found that an ultra thin SiO_x layer has another effect to relax the crystallization strain at a YSX/Si interface. These results indicate that an ultra thin SiO_x layer plays two important roles (a) an ultra thin SiO_x layer formed just above the Si surface serves as a medium for the epitaxial growth of a YSZ layer, and (b)even in an ultra thin SiO_x is able to relax the crystallization strain of YSZ layer at YSZ/Si interface. These are the critical points of the epitaxial growth of YSZ/SiO_x/(001)Si thin film together with a role of an oxygen source reported previously.