Analysis of nanoscale crystalline structure of In-Ga-Zn-O thin film with nano beam electron diffraction

In-Ga-Zn-O thin films formed by a sputtering method, in which distinct crystallinity was not observed by selected area electron diffraction (SAED), were analyzed with nano-beam electron diffraction (NBED). As a result, upon analysis on an about 10-nm-thick area of a sample with the use of a beam with an irradiation area of 1 nmφ, we have found that crystals which are not aligned in a certain direction exist in the In-Ga-Zn-O thin film unlike in an amorphous structure. Further, a result of comparison between NBED measurement results and electron-beam diffraction simulation results has suggested that the In-Ga-Zn-O thin film has a structure different from an amorphous structure and is a group of nano-crystals of In-Ga-Zn-O (nc-IGZOs) with a size of 1.0 nm to 3.0 nm not aligned in a certain direction.