Microstructure of Ge:Ta₂O₅ Granular Thin Films: an Application of TEM-Tomography

Abstract

Microstructure of Ge: Ta₂O₅ granular thin films were observed by Transmission Electron Microscopy (TEM), Scanning Transmission Electron Microscopy with Energy Dispersive Spectrometer (STEM–EDS), and TEM with electron tomography. Three dimensional images Ge: Ta₂O₅ granular thin films were obtained from a tilt series of images, which were taken at regular tilt intervals. Some convex parts of irregular Ge granules, which overlapped by themselves or Ta₂O₅ in this thin film, have been well characterized to explain why there are many Moiré patterns in this Ge: Ta₂O₅ granular thin films. The result acquired by TEM with electron tomography shows Ge crystals have been grown up in a preferred orientation due to the confinement from the surrounding matrix. TEM with electron tomography can be used successfully to show the shapes of Ge particles distributed in the Ta₂O₅ network of this thin film, also the more detailed aspects of grown direction of this granular thin film.